CA2435061A1 - Flux-cored wire for gas-shielded arc welding - Google Patents

Abstract

A flux-cored wire for gas-shielded arc welding comprises a steel sheath, and a flux filled in the steel sheath. The flux-cored wire has a C content of 0.20% by mass or below, Si content in the range of 0.06 to 1.10% by mass, a Mn content in the range of 0.55 to 1.60% by mass, a Cr content of 2.60%
by mass or below, a Mo content in the range of 0.30 to 1.50%
by mass, a Mg content in the range of 0.20 to 1.50% by mass, a N content in the range of 0.005 to 0.035% by mass and a B
content in the range of 0.001 to 0.020% by mass on the basis of the total mass of the flux-cored wire. The flux has a TiO2 content in the range of 4.2 to 8.2% by mass and a fluorine compound content in terms of F content in the range of 0.025 to 0.55% by mass on the basis of the total mass of the flux-cored wire, and the flux-cored wire has an Al content of 0.50% by mass or below, a Nb content of 0.015% by mass or below, and a V content of 0.015% by mass or below on the basis of the total mass of the flux-cored wire. The flux-cored wire forms a weld metal that is resistant to ferrite band maintains proper tensile strength and excellent toughness even if the weld metal is processed at high temperatures for a long time for PWHT.
The flux-cored wire has satisfactory usability

Description

SPECIFICATION
FLUX-CORED WIRE FOR GAS-SHIELDED ARC WELDING
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a. flux-cored wire for gas-shielded arc welding to be used for welding materials formed of heat-resisting low alloy steels and used in various plants, such as nuclear power plants, thermal power plants and petroleum refining plants. More particularly, the present invention relates to a flux-cored wire for gas-shielded arc welding for welding materials formed of heat-resisting low alloy steels, capable of suppressing or completely preventing the formation of ferrite bands in weld metals when the weld metals are subj ected to a post weld heat treatment (hereinafter, abbreviated to "PWHT") at high temperatures for a long time, of forming weld metals having high tensile strength and high toughness, and of facilitating welding work.
Description of the Related Art Welding wires for gas-shielded arc: welding are classified into solid wires and flux-cored wires. Flux-cored wires, as compared with solid wires, have various advantages including capabilities to cause less spattering, to form beads in satisfactory appearance and shape, and to facilitate vertical-position welding and overhead-position welding as well as flat-position welding. Accordingly, the use of flux-cored wires for welding materials formed of heat-resisting low alloy steels have progressively been increased.
Since welded structures formed by welding together materials formed of heat-resisting low alloy steels are used in high-temperature, high-pressure environments, flux-cored wires to be used for constructing such welded structures are required to have characteristics meeting working conditions required bysuch working environments. Generally, weldjoints in materials formed of heat-resisting low alloy steels are subjected to a PWHT to reduce residual stress, to remove residual hydrogen and to improve mechanical property.
Therefore, flux-cored wires for gas-shielded arc welding for welding materials formed of heat-resisting low alloy steels are required to be capable of preventing the deterioration of the characteristics of weld metals.
When a conventional flux-cored wire is used for the gas-shielded arc welding of materialsformed of heat-resisting low alloy steels, ferrite bands are formed in weld metals and the mechanical properties of the weld metals are deteriorated when the weld joints are subjected to a PWHT of high temperatures and a long duratior_. More concretely, ferrite bands reduce the tensile strength of weld metals. It is considered that ferrite band is caused by the segregation of _2-the component metals during the solidification of the weld metals and the migration of carbon contained in the weld metals during the PWHT.
Some techniques have been proposed to solve such problems .
A technique disclosed in JP-B No. 813432 (hereinafter referred to '°Reference 1") adds both Nb and V, which are elements having high ability to form carbides, to a flux-cored wire to suppress ferrite band through th.e suppression of the migration of carbon in weld metals. The inventors of the present invention proposed previously a technique in JP-A No.
2001-324996 (hereinafter referred to as "Referen.ce 2") for suppressing ferrite band by properly adjusting the TiOz, alkaline metal compound and fluoride contents of a titanic flux-cored wire on the basis of knowledge that the improvement of the stability of arcs reduces the segregation of the components of alloys forming the weld metals and the resulting ferri to band and improves the mechanical properties of the weld metals. A technique for improving the toughness of weld metals that adds N in wires in a proper N content is disclosed in JP-A
No . 57-4397 and JP-B No . 62-19959 (hereinafter referred to as "Reference 3") . A zirconia flux-cored wire proposed in JP-B
Nos . 2-42313 and 3-3558 (hereinafter referred to as "Reference 4") reduces the TiOz content of the flux, i.e., a source of Ti, and the Ti content of the wire to the least possible extent by prescribing TiO, ccntent and metal Ti content under predetermined limiting conditions or by prescribing Ti02 content and metal Ti content under predetermined limiting conditions and limiting N content to a proper range on the basis of knowledge that Ti contained in the weld metals reduces the toughness of the weld metals.
Although the technique disclosed in Reference 1 that adds Nb and V to a flux-cored wire is effective in suppressing the migration of carbon to prevent ferrite band. Nb and V are elements that reduce the toughness of weld metals greatly.
Thus, Reference 1 is unsatisfactory in ensuring that weld metals have sufficient toughness. Reference 2 has difficulty in meeting demand for higher toughness . Reference 3 does not disclose any technique for preventing ferrite band and does nat disclose any technique for ensuring that weld metals have satisfactory toughness, and preventing ferrite band. The zirconia flux-cored wire disclosed in Reference 4 is inferior to titania flux-cored wires in wire usability in a vertical position and an overhead position.
STJWARY CF THE IN~~TENTION
The present invention has been made in view of the foregoing problems and it is therefore an obj ect of the present invention to provide a flux-cored wire for gas-shielded arc welding, capable of forming weld metals resistant to the formation of ferrite bands therein even when the weld metals are subj ected to a high-temperature PWHT for a long time, and of forming weld metals having high toughness.
According to the present invention, a flux-cored wire for gas-shielded arc welding comprises: a steel sheath, and a flux packed in the steel sheath; whereir_ the flux-cored wire has, on the basis of the total mass of the flux-cored wire, a C content of 0.20s by mass or below, a Si. content in the range of 0.06 to 1.10o by mass, a Mn content in the range of 0.55 to 1.60 by mass, a Cr content of 2.600 by mass or below, a Mo content in the range of 0. 30 to 1. 50 o by mass, a Mg content in the range of 0.20 to ? .50% by mass, a N content in the range of 0. 005 to 0. 035 by mass and a B content in the range of 0 . 001 to 0.020% by mass; the flux has, on the basis of the total mass of the flux-cored wire, a TiOz content in the range of 4.2 to 8.2% by mass and a fluorine compound content in the range of 0. 025 to 0 . 55~ by mass in terms of F content; and the flux-cored wire has, on the basis of the total mass of the flux-cored wire, an A1 content of 0 . 50~ by mass or below, a Nb content of 0 . 01.5 0 by mass or below, and a V content of 0 . O1 ~ o by mass or below.
In the flux-cored wire for gas-shielded arc welding according to the present invention, it is preferable that the Mn content is in the range of 0 . 55 to 1 . 45 o by mass on the basis of the total mass of the flux-cored wire. It is preferable that the flux-cored wire for gas-shielded arc welding according to the present invention contains at least one selected from the group consisting of Ti other than Ti02 in a Ti content in the range of 0 . 005 to 0 . 3 o by mass and Zr in a Zr content in the range of 0.002 to 0.3'% by mass on the basis of the total mass of the flux-cored wire. It is preferable that the flux-cored wire according to the present invention meet a condition that the ratio of total Ti content to N content is in the range of 250 to 500 (the total Ti content and the N content are the Ti content and the N content on the basis of the total mass of the flux-cored wire).
BRIEF DESCRIPTION OF THE drawings The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in connection with the accompanying drawings, in which:
Fig. 1 is a typical sectional view of workpieces provided with a groove for an example and a comparative examples and Fig. 2 is a graph showing the dependence of the Charpy impact energies ?",~,VE_,goC (Avg. ) of weld metals produced by using flux-cored wires in examples of the present invention on the ratio of total Ti content to N content of examples.
DESCRIPTTON OF THE PREFERRED EMBODIMENTS
Referring to the drawings, an embodiment of the present invention will be described below.
_6_ The inventors of the present invention made tests and studies earnestly to solve the foregoing problems. Conven-tional titania flux-cored wires respectively having different Nb and V contents for welding materials formed of a heat-resisting low alloy steel containing 1.2a o Cr and 0. 5 o Mo were used. Test pieces formed of a steel containing 1.25 Cr and 0 . 5 o Mo were welded by using the foregoing flux-cored wires .
Weld metals thus obtained were subjected to a high-temperature PWHT for a long time, and then the microstructure of the weld metals was observed. The PWHT heated the weld metals at 690°C
for 9.5 hr, and then the weld metals were cooled by furnace cooling.
The observation of the microstructure of the weld metals showed that various precipitates containing Nb, V and Ti produced through the reduction of Ti02 were distributed in grains and grain boundaries of the weld metals ~ It was known taut grain boundaries were fixed by the pinning effects of those precipitates, i . a . , an effect to fixate the present. state by preventing the migration of atoms and grain boundaries, and, consequently, ferrite band was suppressed. It was known that the pinning effect of Various precipitates containing Ti and other elements suppressed the migration of grain boundaries during the PWHT and thereby ferrite band T.aas suppressed.
It was known that the suppression of the migration of grain boundaries during the PWHT by the pinning effect of various precipitates containing Ti and other elements sup-pressed ferrite band. Such a ferrite band suppressing method is different from a conventional ferrite band suppressing method that adds Nb and/or V in weld metals to precipitate a Nb carbide and/or V carbide to suppress ferrite band by suppressing the migration of C atoms during PWHT. According to the present invention, a flux-cored wire having a flux containing titanic is used as a Ti source for supplying Ti as a pinning material. Ti produced by reducing TiO~ inevitably contained in weld metals is combined with N to produce a TiN
precipitate.
The present invention has been made on the basis of the aforesaid knowledge and idea. The followings are essential conditions to be satisfied to achieve the object of the present invention.
(1) Promoting the reduction of Tit~~ by adding proper amounts of 5i, Mn, Mg and F compounds to weld metals, and precipitate of TiN by adding a proper amount of N to weld metals and reducing TiO~ to produce Ti, to restrict the formation of ferrite band effectively (2) Fining micrcstructures by adding a proper amount of B to wel d metals to enhance the toughness of the weld metals, regulating Nb and V contents of weld metals to prevent the reduction of the toughness of weld metals du.e to the precipitate of MX-type Nb and V carbides during PWHT, and regulating A1 _g_ content to prevent the reduction of the toughness of weld metals due to embrittlement (3) Optimizing arc stabilizer content, such as Ti02 content and fluorine compound content, to ensure satisfactory welding work, forming slag having satisfactory viscosity, and preventing spattering Limiting conditions on the composition of flux-cored wires according to the present invention for gas-shielded arc welding will be described below. The content of the component of a flux-cored wire is expressed in percent by mass on the basis of the total mass of the wire.
C Content: 0.2o by mass or below Carbon enhances the hardenability of steels and improves the tensile strength and toughness of weld metals. Therefore, carbon is added to either the steel sheath or the flux or both the steel sheath and the flux of the flux-cored wire. If the C content of the flux-cored wire is greater than 0.20 o by mass, the tensile strength of the weld metal is excessively high, the toughness of the weld metal is very low and hot cracking is liable to occur in the weld metal . Thus, the carbon content of the flux-cored wire :must be 0 . 20 o by mass or below. Carbon, such as graphite, or an alloy, such as chromium carbide, Si-C, high C-Fe-Mn or high C-Fe-Cr, is used to add carbon to the flux.
Preferably, the carbon content of the flux--cored wire is 0 . 03 0 by mass or above.
_g_ Si Content: 0.06 to 1.10 by mass Silicon serves as a deoxidizer for deoxidizing the weld metal. Silicon increases the viscosity of the weld metal and has an effect to adjust the shape of a bead. Silicon has the effect of promoting the reducing reaction of Ti02 and stabilizing the recovery of B into the weld metal. Silicon is added to either the steel sheath or the flux, or to both the wire and the flux for those purposes . However, if the Si content of the flux-cored wire is below 0.060 by mass, the deoxidizing effect of silicon is insufficient, blow holes are liable to be formed in the weld metal, beads of unsatisfactory shapes are formed due to the insufficient viscosity of the weld metal, and a sufficient amount of TiN effective in suppressing ferrite band cannot be produced due to the insufficient reduction of TiOz. Moreover, if the Si content of the flux-cored wire is be=Low 0.06% by mass, the recovery of B in the weld metal is low, the microstructure of the weld metal cannot be fined and the toughness of the weld metal is low.
If the Si content of the flux-cored wire i~s greater than 1.10°
by mass, the tensile strength of the weld metal is excessively high, and the toughness of the weld metal decreases because Ti02 is reduced excessively and the solid solution of Ti increases . Therefore, the Si content must be in the range of 0.06 to 1.100 by mass. A.n alloy, such as Fe-Si, Fe-Si-Mn or Fe-Si-Cr is used to add Si to the flux.

Mn Content: O.:i5 to 1.60% by mass preferably, 0.55 to 1.450 by mass) Manganese serves as a deoxidizer for deoxidizing the weld metal, enhances the =.Zardenability of tkie weld metal, and improves the tensile strength and toughness of the weld metal.
Manganese, similarly to Si, promotes the reduction reaction of Ti02 and stabilizer the recovery of B into the weld metal.
Mn is added to either the steel sheath or the flux or to both the steel sheath and the flux far those purposes. If the Mn content of the flux-cored wire is 0.550 by mass or below, the deoxidizing effect of Mn is insufficient, blow holes are liable to be formed, the tensile strength of the weld metal is insufficient, and a sufficient amount of TiN effective in suppressing ferrite band cannot be produced due to the insufficient reduction of TiO~. If the Mn content of the flux-cored wire is 0 . 55 ~ by mass or below, the recovery of B
into the weld metal decreases, the microstructure of the weld metal cannot be fined and the toughness of the weld metal decreases. On the other hand, if the Mn content of the flux-cored wire is greater than 1.600 by mass, the shape of beads formed by vertical-position welding and over-head-position welding is deteriorated greatly due to the excessively high fluidity of the molten weld metal, the tensile strength of the weld metal is excessively high, the amount of the solid solution of Ti increases due to the excessive reduction of Ti02 to reduce the toughness of the weld metal.
Thus, the Mn content of the flux-cored wire must be in the range of 0.55 to 1.6% by mass. It is preferable that the Mn content of the flux-cored wire is 1 .45% by mass or below because beads can be formed in a satisfactory shape if the M:n content of the flux-cored wire is 1. 45 % by mass or below. For the foregoing purposes, a metal, such as metal Mn, an alloy, such as Fe-Mn, or Fe-Si-Mn is used to add Mn to the fltax.
Cr content: 2.6o by mass or below Chromium is an important component of a heat-resisting low alloy steel and has an effect of im.prov~_ng the tensile strength of the weld metal. Chromium is added to either the steel sheath or the flux or to both the steel sheath and the flux for that effect. The Cr content of the flux-cored wire is adjusted properly according to the quality of a metal to be welded. On the other hand, the tensile strength of the weld metal is excessively nigh and the toughness of the weld metal is low if the Cr content of the flux-cored wire is greater than 2.60% by mass. Thus, the Cr content of the flux-cored wire must be 2.6% by mass cr below. A metal, such as metal Cr, or an alloy, such as Fe-Cr, is used to add Cr to the flux.
Preferably, the Cr content of the flux-cored wire is 0.10% by mass or above.
Mo content: 0.30 to 1.50% by mass Molybdenum, similarly to Cr, is an important component of a heat-resisting low alloy steel and has an effect of improving the tensile strength of the weld metal. Molybdenum has the effect of increasing the resistance to temper softening of the weld metal and suppressing the reduction of the tensile strength by the PWHT . Molybdenum is added to either the steel sheath or the flux or to both the steel sheath and the flux for that effect. ThE: Mo content of the flux-cored wire is adjusted properly according to the quality of a metal to be welded. The tensile strength of the weld metal is insufficient if the Mo content of the flux-cored wire is less than 0.30%
by mass . On the other. hand, the tensile strength of the weld metal is excessively high and the toughness ov the weld metal is low if the Mo content of the fi~ax-cored wire is greater than 1.50% by mass. Thus, the Mo content of the flux-cored wire must be in the range of 0. 30 to 1 . 50% by mass . A metal, such as metal Mo, or an alloy, such as Fe-Mo, is used to add Mo to the flux.
Mg content: 0.20 to 1.50% by mass Magnesium is a potent deoxidizer for deoxidizing the metal weld and is added to the flux-cored wire to enhance the toughness of the weld metal. Preferably, Mg is added to the flux for such an action and such an effect. Magnesium, similarly to Si and Mn, has the effect of promoting the reduction reaction of Ti02 and stabilizir.:g the recovery of B
into the weld metal. Magnesium is added to either the steel sheath or the flux cr to both the steel. sheath and the flux for those effects. if the Mg content of the flux-cored wire is less than 0.20 by mass, the deoxidizing effect of Mg is insufficient, blow holes are liable to be formed, the amount of oxygen increases and the toughness of the weld metal is low.
Moreover, if the Mg content of the flux-cored wire is less than 0.200 by mass, a sufficient amount of TiN that suppresses ferrite band cannot be produced due to the insufficient reduction of Ti02, the recovery of B into the weld metal is low, the microstructure cannot be fined and the toughness of the weld metal is low. On the other hand, if the Mg content of the flux-cored wire is greater than 1 . 50s by mass, spattering intensifies, the covering ability of slag deteriorates, the shape of beads formed by vertical-position welding and overhead-position welding is deteriorated, the toughness of the weld metal is reduced because Ti02 is reduced excessively and the amount of the solid solution of Ti increases . Thus, the Mg content of the flux-cored wire is in the range of 0.20 to 1.50 by mass. A Ntg source is a metal Mg or a Mg alloy, such as Si-Mg or Ni-Mg.
N content: 0.005 to 0.0350 by mass Nitrogen combines with Ti to precipitate TiN having the effect of suppressing ferrite band in the weld metal. N has the effect of fixating the solid solution of Ti in a nitride to improve the toughness of the weld metal. Nitrogen is added to either the steel sheath or the flux or to both the steel sheath and the flux for those effects. If the N content of the flux-cored wire is less than 0.0050 by mass, the effect of suppressing ferrite band is unavailable due to the insufficient precipitate of the nitride as well as the solid solution of Ti cannot be reduced and the toughness of the weld metal is low. On the other hand, if the N content of the flux-cored wire is greater than 0 . 035 o by mass, the toughness of the weld metal is reduced due to the increase of the solid solution of N, excessive N forms blow holes and slag removability deteriorates. Thus, the N content of the flux-cored wire must be in the range of 0 . 005 to 0 . 035 o by mass .
A metal nitride, such as N-Cr, N-Si or N-Ti, is used to add N to the flux-cored wire.
B content: 0.001 to 0.020 by mass Boron has the effect of fining the microstructue of the weld metal and improving the toughness of the weld metal.
Boron is added to either the steel sheath or the flux or to both the steel sheath and the flux for that effect. The toughness improving ef:~ect of B is insufficient if the B content of the flux-cored wire is less than 0.001 by mass. On the other hand, the weld metal is subject to hot cracking if the B content of the flux-cored wire is greater than 0 . 020 o by mass .
Thus, the B content of the flux-cored wire is in the range of 0.001 to 0.020 by mass. An alloy, such as E'e-B or Fe-Si-B, or a boron oxide, such as B2O3, is used to add B to the flux.
When a boron oxide is added to the flux, the B content is adjusted on the basis of the boron oxide content in terms of B content.
Ti02 content: 4.2 to 8.2o by mass Titanium oxide is a principal slag-forming material and serves as an arc stabilizer. Part of TiO~ is reduced by Si, Mn, Mg and a fluorine compound to produce Ti, and the Ti combines with N to precipitate TiN in the weld metal. The TiN thus precipitated is very effective s.n suppressing ferrite band.
Since Ti02 is a principal slag-forming material and the reduction reaction of part of Ti.02 occurs easily in a hot atmosphere, Tioz is contained in the flL~x to promote the reduction reaction of Ti07. If the TiO~ content of the flux is less than 4.2% by mass, arcs become unstable, welding work becomes practically impossible and only a small amount of Ti is produced by reduction and, the effect of Ti02 in suppressing ferrite band is insufficient: because a small amount of Ti is produced by reduction arid the amount of precipitated TiN decreases. On the other hand, if the Ti02 content of the flux is greater than 8.2o by mass, slag has a very high ~riscosity causing welding defects including slag inclusion, slag inclusion increases the amount of oxygen contained in the weld metal to reduce the toughness of the weld metal. Thus, the TiO~ content of the flux must be in the range of 4.2 to 8.2~ by mass.
Fluorine compound content in terms of F content: 0.025 to 0.550 by mass A fluorine compound serves as an <~rc stabilizer. A
fluoride compound has effects of lowering the melting point of slag, improving the fluidity and covering ability of slag, forming beads in a satisfactory shape. Fluorine gas produced by the decomposition and gasification of a fluorine compound by arcs has effect of stirring the molten metal to promote the separation of slag from the molten metal and redL:cing the amount of oxygen contained in the weld metal. A.f~uo nine compound, similarly to Si, Mn and Mg, has effects oj: mak:~ng Ti produced by reducing TiOZ combine with N to precipitate TiN in the weld meal to suppress ferr.te band, and stabilizing the recovery of B into the weld metal. Since a fluorine compound serves as one of a slag-forming materials and the reduction reaction of part of Ti02 occurs easily i n a hot atmosphere, the fluorine compound is added to the flux to promote the reduction reactior_ of TiOz. If the fluorine compound content in terms of F content of the flux is less than 0.025 by mass, this effect is una~railable, arcs are unstable, spattering intensifies and the shape of beads is deteriorated. Moreover, if the fluorine compound content in terms of F content of the flux is less than 0 . 025 o by mass, blow holes are liable to be formed due to the insufficient effect of reducing the amount of oxygen contained ir_ the weld metal microstructure cannot be fined due to the reduction of the recovery of B into the weld metal to reduce the toughness of the weld metal Still further, if the fluorine compound content in terms of F content of the flux is less than 0.025° by mass, since the amount of Ti produced through the reduction of Ti02 is small due to the insufficient reduction of TiOz, the amount of precipitated TiN is ,mall and sufficient effect of suppressing ferrite band is unavailable. On the other hand, if the fluorine compound content in terms of F
content of the flux is greater than 0. 55 o by mass, the fluidity of slag is excessively high, the covering performance is spoiled and the shape of beads is deteriorated significantly.
Thus, the fluorine content in terms of F content of the flux must be in the range of 0.025 to 0.550 by mass. Possible fluorine compounds are: LiF, NaF, K2SiF6, CaF2, MgF2, BaF2, CeF3 and a fluorine oil containing CF2. The flux-cored wire may be coated with the fluorine oil containing CF.~ to use the fluorine oil as a lubricant.
A1 content: 0.50° mass or below Aluminum serves as a deoxidizer for deoxidizing the weld metal and has effects of preventing the formation of blow holes in beads and transferring droplets in spray, Aluminum is added to either the steel sheath or the flux or to both the steel sheath and the flux for the aforesaid effects. If the Al content of the flux-cored wire is greater than 0. 50 o by mass, ,. ..._..,.,. ..;: weld metal hardens and becomes brittle, the tensile strength of the weld metal is excessively high a.nd the toughness of the weld metal is very low. Thus, the Al content of the flux-cored wire must be 0.50% by mass or below. Alumina contained in the flux-cored wire is decomposed by high- .
temperature arcs and A1 is produced. Therefore, an A1203 content is converted into an equivalent Al content.
Preferably, the Al content of the flux-cored wire is 0.03% by mass or above.
Nb content: 0.015% by mass or below Niobium contained in the weld metal makes carbides contained in the weld metal precipitate. The carbides thus precipitated have an effect of suppressing the migration of atoms during PWHT and suppressing ferrite band. However, Nb combines wi th C to form a minute, MX-type carbide when subj ected to PWHT. The MX-type carbide reduces the toughness of the weld metal significantly i~= the Nb content of the flux-cored wire is greater than 0.015% by mass. Thus, the Nb content of the flux-cored wire must be 0 . 015 o by mass or below. The niobium oxide content is converted into an equivalent Nb content.
V content: 0.015% by mass or below Vanadium contained in the weld metal, similarly to Nb, makes carbides contained in the weld metal precipitate to suppress ferrite band by suppressing the migration of C atoms during PWHT. However, V combines with C to form a minute, MX-type carbide when subjected to PWHT. The MX-type carbide reduces the toughness of the weld metal significantly if the V content of the flux-cored wire is greater than. 0 . 015 o by mass .
Thus, the V content of the flux-cored wire must be 0.015s by mass or below. The vanadium oxide content is converted into an equivalent V content.
Ti content: 0.005 to O.So by mass Titanium serves as a deoxidizer for deoxidizing the weld metal and has effects of improving the toughness of the weld metal. Titanium combines and produces TiIV that is effective in suppressing ferrit~s band. Thus, it is pre~fera'o1e to add a proper amount of Ti to the flux-cored wire to improve the toughness of the weld metal and to suppress ferrite band.
Titanium is added to either the steel sheath or the flux or to both the steel sheath and the flux for the aforesaid effects.
An acid-soluble Ti-containing substance is added to the steel sheath. Metal Ti or a Ti-bearing alloy, such as ie-Ti, is added to the flux. Differing to Ti produced through. the reduction of Ti02, Ti contained in such a form in the flux-cored wire is not subject to the reducing effect of deoxidi zers other than Ti, such as Si, Mn and Mg, and remains in the weld metal . Thus, the recovery ef Ti into the weld metal is satisfactory and Ti can stably contained in the weld metal. Titanium contained in Ti02 is acid-insoluble Ti. The toughne ss of the weld metal cannot be improved if the weld metal contains Ti in a form other than Ti02, i.e., acieL-soluble Ti, in a 'Ti content less than 0.005° by mass of the flux-cored wire. If the weld metal contains Ti in an acid-soluble Ti, in a Ti content greater than 0.3~ by mass of the flux-cored wire of the flux-cored wire, the tensile strength of the weld metal is excessively high, the amount of the solid solution of Ti is large and the toughness of the weld metal is low. Thus, the Ti content of the flux-cored wire in terms of Ti other than Ti02 is in the range of 0.005 to 0.3o by mass of the flux-cored wire.
Zr content: 0.002 to 0.3~ by mass Zirconium serves as a deoxidizer and has an effect of improving the toughness of the weld metal. Zirconium con-tamed in the flux-cored wire improves the toughness of the weld metal additionally. Therefore, it is preferable that the flux-cored wire contains Zr in a proper Zr content to further improve the toughness of the weld metal. Zirconium is added to either the steel sheath or the flux or to both the steel sheath and the flux for such an effect. Zirconium is unable to further improve the toughness of the weld metal when the Zr content of the flux--cored wire is less than 0.002 by mass.
The Zr content of the flux-cored wire exceeding 0 . 3 o by mass does not exercise any particular effect. Thus, the Zr content of the flux-cored wire must be in the range of 0.002 to 0.3~
by mass of the flux-cored wire. Metal Zr or a Zr bearing alloy, such as Fe-Zr or Fe-Si-Zr, is used for adding Zr to the flux.

The respective actions and effects of Ti and Zr contained in the flux-cored wiy-e are independent of each other.
Therefore, it is preferable that the flux-cored wire contains either Ti or Zr and it is more preferable that the flux-cored wire contains both Ti and Zr.
Ratio of total Ti content to N contento 250 to 500 Both the solid solution of Ti and the solid solution of N contained in the weld metal are reduced and the toughness of the weld metal is further improved b_y adjusting the quantities in percent by mass of the components of the fl ux-cored wire so that the ratio of the total Ti content of the flux-cored wire, i.e., the sum of a Ti content based on Ti contained in the form of Ti02 in the flux-cored wire, and a Ti content based on 'fi contained in the steel. sheath and/or he f 1 ux to the N con tent o f the flux-cored wire, i . a . , ( Total Ti content)/(N content) is in the range of 250 to 500.
A. desired flux-cored wire of the present invention to be used for welding materials formed of heat-resisting low alloy steels by gas-shielded arc welding can be obtained when theflux-cored wire has the foregoing composition. Therefore, there are not any particular restrictions on the quantity in percent by mass and the composition of the slag-forming materials contained in the flux-cored wire. The slag-forming materials contain nonmetallic components and form slag that covers the molten meta 1 to isolate the molten metal from the ambient atmosphere around the weld joints during gas-shielded arc welding. More specifically, the slag-forming materials are TiOz, which is one of the components o.f the flux-cored wire for which contents are specified, the fluorine compound, A1203, boron oxide, niobium oxide and vanadium oxide, substances for the fine adjustment of the basicity of slag or the melting point, viscosity and fluidity of slag, such as Zr02, Si02, Ca0 and MgO, and substances for the fine adjustment the condition of arcs, such as K20 and Na20.
There is not any particular restriction on the quality and composition of the steel sheath of the flux-cored wire of the present invention, provided that the quality and composition of all the components of the flux-cored wire including the steel sheath and the flux meet the specified conditions.
The flux of the f lux-cored wire of the present invention does not need to be filled in the steel sheath in a particularly specified flux ratio. The flux ratio may properly be determined, taking into consideration the productivity of the flux-cored wire, and process conditions, such as the possibility of breakage of the steel sheath during forming and drawing. Preferable flux ratio is in the range of, for example, 11.0 to 18.0o by mass.
The shielding gas may be any one of COz gas, an Ar-C02 mixed gas of any suitable composition, an Ar-C~ mixed gas of any suitable composition and an Ar-COz-02 mixed gas of any suitable composition. Preferably, the composition of the steel sheath may selectively be determined according to the composition of materials to be welded. Possible materials of the steel sheath include mild s-teels and alloy steels . There is not any particular restriction on the sectional shape of the steel sheath; the steel sheath may be either a seamed tube or a seamless tube.
The flux-cored wire of the present invention may contain, when necessary, components other than those mentioned above, such as Cu, Ni, Co and/or W to meet abilities required of the material to be welded.. When the steel. sheath is a seamless tube, the surface of i:he steel sheath may be plated with Cu, Ni or a composite material.
As mentioned above, it is one of the features of the present invention to promote the reduction of Ti02 by adding proper quantities of Si, Mn, Mg and fluorine compound to the weld metal. It is possible to reduce Ti02 satisfactorily, provided that Si, content, Mn content, Mg r_ontent and fluorine compound content are in the aforesaid ranges, respectively.
Examples The effects of flux-cored wires of the present invention in examples will be described in comparison 4,rith those of flux-cored wires in comparative examples.
Fl ux-cored wires listed in Tables 3 to 11 were fabricated, using sheaths of mild steels (sheath types A and B) and those of Cr-Mo steels (sheath types C and D) respectively having chemical compositions shown in Tables 1 and 2. The respective outside diameters of all the flux-cored wires were 1.2 mm.
Test plates l, i.e., workpieces, of heat-resisting low alloy steels having a thickness of 19 mm, and spaced by a groove shown in Fig. 1 were subjected to butt gas-shielded arc welding under welding conditions shown in Tables 12 and 13. The heat-resisting low alloy steels were a 0.5o Mo steE~l (A204, Gr. A, JIS), a 1.25% Cr-0.5o Mo steel (A387 Gr. 11, Cl. 2, JIS), a ~~.25% Cr-1.0% Mo steel (A387, G4. 22, Cl. 2, JIS). Table 12 shows the welding conditions fog forming weld metals to be subj ected to performance tests, and Table 13 shows the welding conditionsfor usability tests. The groove formed between the plates 1 was a V-groove having a groove angle of 45° and a raot gap of 13 mm.
Test welding were performed for the following test items and performance evaluation items.
(1) Evaluation c~f the Performance of Weld Metals Weld metals were made by flat-position welding using flux-cored wires in Comparative examples 1 t:o 29 shown in Tables 3 to 6 and flux-cored wires in Examples 1 to 35 shown in Tables 7 to 11 under welding conditions for flat-position welding shown in Table 12. The weld metals were examined by ra-diographic examination. It was decided that the weld metals having qualities meeting those specified in 23104 1, JIS were good and the rest were bad.
The weld metals were subjected to tensile tests and Charily impact tests after PWHT. Only the weld metal made by welding the plates 1 of the 0.5% Mo steel by using the flux-cored wire in Example 7 was kept at 620°C for 1 hr and cooled by furnace cooling for PWHT, while the weld metals formed by using the rest of the flux-cored wires were kept at 690°C for 1 hr arid cooled byfurnace cooling. Tensile test measured 0.2a-offset yield strength and elongation. Acceptance conditions for tensile performances represented by measured values measured by mechanical measurement were specified for the qualities of the plates 1, i . a . , qualities of test plates shown in Tables 15 to 23, respectively. Table 14 shows tensile performance acceptance conditions for Examples and Comparative examples.
Three No . 4 Charily test specimens provided with a 2 mm V notch of each weld metal were subj ected to Charily impact test at -18°C
and amounts of energy absorbed by the test specimens were measured, and the impact performance of the weld metal was represented by the average of the three measured values . The range of acceptable impact performance wa s 55 J or above, which was expressed by: 2~,~"E_13~~ (Aug. ) z 55 J.
Test specimens were treated for a long time by a PWHT
using a high temperature and then examined fo r ferrite band in the weld metals . Test specimens formed by welding plates of a 0.5o Mo steel and a 1.250 Cyr-0.5o Mo steel were kept at 690°C for 9.5 hr and cooled b furnace cooling. Test specimens formed by welding plates of 2 . 25 o Cr-1 . 0 o Mo steel were kept at 690°C for 15.3 hr and cooled by furnace cooling. The qualities of the test plates 1 (,types of steels of the test plates) and the compositions of the shielding gases are shown in Tables 15 to 23 showing test results. Sections for microstructure observation were sampled from ;aix parts of the weld metal at equal intervals along the weld line of the weld metal after PWHT and the sections were polished by mirrorlike finishing and finished by etching to obtain six test specimens for the observation of microstructure. The test specimens were observed by an optical microscope to see if any ferrite bands are formed. It was decided that i~.he ferrite band suppressing abilities of the flux-cored wires were acceptable when any ferrite bands were not found in any one of the six test specimens of each weld metal and that the same were unacceptable when ferrite bands are found in any one of the six test specimens of each weld metal. 'The weld metals were analyzed to determine the chemical compositions thereof.
(2) Evaluation of Wire Usability Weld metals were produced by flat--positior_ welding' as mentioned in ( 1 ) and by fillet welding in. a vertical position under conditions shown in Table 13 using the flux-cored wires in Examples 1 to 33 shown in Tables 6 to 11 and the flux-cored _?7_ wires in Comparative examples 1 to 29 shown in Tables 3 to 6.
The usability of the f~_ux-cored wires was evaluated by sensory tests in terms of arc stability during welding, slag removability, spattering intensity and bead shape.
Results of all those tests and the results of evaluation are shown in Tables 15 50 23.
... Tables I to 23 ...
Table 1 (Unit: Percent by mass) ~ Name of materialC Si Mn ~ P S ! Cr ~ Quality i Cu I
Ni ~

A j 0.036 <0.010.20 0.012 0.007 X0.0130.014 0.020 ~

Mild steel B ~ 0.010 <0.010.25 0.006 0.004 0.011 0.012 0.019 ~

C 0.025 0.50 1.14 0.003 0.007 0.012 0.084 1.39 ~

Cr-Mo alloy steel--t i D 0.031 0.48 1.10 0.007 0.005 0.013 0.031 E 2.44 ;

Table 2 {Unit: Percent by mass) Name of material Quality Ma ~ AI r i Nb ~ ~l 8 N Mg A ~ 0.005 0.038 <0.002 0.003 <0.002 <0.0002 0.0024 <0.002 Mild steel B 0,002 0.008 ( <0.002 0.003 <0.002 <0.0002 i 0.0033 ~ <0.002 C 0.48 0.004 0.002 0.003 0.003 <0.0002 0.0080 <0.002 Cr-Mo alloy steel D 1.10 ~ 0.002 <0.002 0.003 0.004 ( <0.0002 0.0090 <0.002 _2g_ Table 3 Wire Comparative iComparativeComparative No. Comparative exampleComparativeiComparative Comparative 4 Comparative) example ex_ '. ample exam Ei 7e exam 2 ie example 6 3 exam 7e exam to i Sheath j B B B 8 I B B
uaii B B I
j Flux 17_0 _17.0 17.0 14.0 14.0 16.0 I 16.0 16.0 ratio j /
b mass Siag-forming material 8.2288.228 8.228 6.776 ~ 7.6961.744 7.760 content 6.776 b mass C 0.2180.039 0.040 0.038 0.0550.042I 0.0420.037 .

Si 0.6640.051 1.415 0.537 0.5660.615 I ' 0.593 0.424 Mn 1.4511.381 ! 1.3870.541 1.6231.369I 1.3731.364 0.0070.007 0.007 0.007 0.0070.0070.007 I 0.007 i S 0.0050.005 ! 0.005O,DOS 0.0050.005I 0.005l O.OOS
!

Cu 0.0090.010 0.009 0.010 0.0100.0090.010 ; 0.009 Ni 0.0100,010 i 0.0100.010 0.0100.010I 4.010j 0.010 I

Cr 1.5251.322 1.325 1.267 1.2672.659I 1.396I 2.396 - I I

Mo 0.503_0.502 . 0.5020.413 0.4134.953I 0.292j 1.524 I

i AI {Sheath 0.0110.007 j 4.0330.091 0.0110.011I 4.0110.011 alloy powder) ~ Equivalent OW 0.045 ' 0.045O.D37 0.0374.0280.043 0,042 ~ Al content) ~

( Total I 0.0560.052 ! 4.0780.048 O.DdBI I 0.054I 0.053 I 4.039 I

r D.oo10.001 0.003 0.401 - 0.001j 0.001j o.001 i ; I I 0.001 I 0.002O.D02 I 0.0020.002 0.002I I 0.002; 0 Nb I 4.002 402 (Sheath, alloy powder}
;

iNb~NbzCs 0.0000.000 I 0.0000.000 O.C00, I 0.000.
~ I , I 0.000 ,(Eguivalent , 0.000 I
Nb ;
content) i ~

Cue- 0.0020.002 I 0.0020.002 0.002i I 0.0021 0.002 . ~ O.D41 ! 0.001 0.0010.002! 0.001. 0.001 'To~i 0.001 ! 0.D01 0.001 l ! ' position ' ';V
{Sheath, allay powder) '~
~

%b , 0.004 i 0.0040.003 D.D030.003~ 0.003, 0.003 mass} 0.004 ~
~ I
V
~{Egu'rvalentVcontent}
'' I 0.0050.005 ; 0.0050.004 0.404~ O.OD4 Total 0.004 8 0.0000.000 j 0.0000.000 0.000~ ~ 0.000! 0.000 {Sheath, i I j 0.000 I
allay powder) 8,0.
B 0.0080.008 I 0.0080.007 0.007I ! 0.0080.007 i j ( 0.008 ' ;
(Equivalent B
content) '~Totai 6.0080.408 ! 0.0080.007 0.0070.4084.008 i 0.007 I 1 j l 0.0140.015 I 4.0150.013 0.013O.D140.014 0.014 N ! I

j 0.7980.798 0.198 0.657 0.657 Mg ~ !
0.751 I
0.751 ( 4.639 zr o.aooo.aoo a.ooo o.aoo D.DOOo.040D oao i a.o4o I I

TiC, 7.3207.320 ' 7.3206.028 6.028i ~ 6.8896.889 I i 6.889 SiO, 0.3860.386 I 0.3860.318 0.3180 0.363 ! 0.360 ' j ~ 255 I 0.085_0.085 j 0.0850.070 D.07D0.0520.080 j 0.080 AI,C, I j I

ZIO, 0.000O.D40 0.000 0.000 0.000i 0.000 i 0.011 ~ ~ 0.4000 j D.CODO.G00 i O.D000.000 4.000O.i560.000 j 0.000 ~~9C I ~
I

' 0.0070.007 j 0.0010.005 0.005. 0.006 I 4.006 ~z~s ' I 0.006 I -y 0.0000 000 ; 0_0_000.000 0.0000.0004.000 0.000 ~ ' j I
Nb,05 ~

Na,O 0.0500.050 0.050 0.041 _ I 0.047 0.044 I _' _ ~ _ 0.042 0.041 ~'I 0.0390.439 j 0.0380.032 0.032~ 0.037 I 4.037 K,0 ~ ' 0.024 I

Ca0 0._0000.000 I 0.0000.000 0.000j 0.040 j 0.000 ! 0.002 B,C, 0 0.027 i, 0.022 0.0220.0260.026 0.023 ~ 027 0.027 c ~i , .

~ O.D400.000 I 0.0000.000 4.0000.075I 0.000 ~ j ~ 0.045 ;
NaF
_ _-.
-K,Si~F, 0.3040.304 0.304 0.250 _ 0.080' 0.286i 0 I 0.250 159 I 0.4000.000 0.000 0.000 0.000~ ~~ 0.000.
o ; 0.066 ' 0 ~CeF, 066 ~

~ 0.0000.000 , 0.0400.000 0.0004.000! 0.000 CaF, 0.1570.157 i 0_ 0.130~ j 0.148~ 0.130 I ~ 0.157130 0.094 I ~ , s I ~
i Total I
Equivalent F
content Other 0.0090.009 ; 0.0094.008 O.DOBI n nn4 I n elements , n me I n~~ i I j Total TiIN I 313 287 290 ' 276 277 I 287 2g5 ~ 287 Table 4 Wire ComparativeI ComparativeComparativ~,m~,e ' ComparativeComparativeComparative No.

exam exam exam examoieexam exam exam 7e !e 7e 12 7e 7e 7e 9 10 11 13 14 t5 ~

Sheath i g g B g ual Flux 18.0 18.0 15 15 ratio 0 0 /
b mass . . 15.0 15.0 13.0 i Slag-forming material content / 8.33.4 8.712 6.795 ' 7.2456.195 6.495 7.012 b mass 0 ' 0.0460.051 _0.044O.D~44 ~ 0.0440.044 0 Si 0.670 0.459 0.383 0.3,33 0.383 0.383 .

Mn 0.975 ~ 1.5201.310 1.309 t.310 1.3t1 .

O.OOl 0.007_0.007 _ 0.007 0.008 .
~ O.Oa7 0 S ' 0.0050.005 0.005 0.005 0.005 0.005 .

i ~u o.DID~ o.oos X0.010' D.DIaD.olO o.olD .
~ o 0l0 Ni ( T o 010 0.010 0.010 0.010 0.010 .
D.om ; o alo Cr ! t .568 1.623 , t 1.3;16 1.356 ( t .
.356 .356 t t Ma ( 0._565 0.531 ( 0.4430.4<~,30.443 l 0.443.

AI Sheath, 0.020 0.465 ~ 0.0070 0 0 .
alto owder 007 007 007 ~

. . . 0.007 ~0' 0.49(7 0.048 0.040 0.0<L7 0.040 0.039 0.033 EctuivalentAl content) I

Total O.S1D O.St3 0.047 O.O;i4 I 0.0460 I 0.047 040 I

I o.aon 0.001 o.oa1 j o.ao1 0.001 .
' 0.401 D

I 0.002 0.002 0.016 0 I 0 .
Nb Sheath, I I 0()9 002 alto wrier . 0 . . ~ 0.002 IN .
NbZO' b1 D.CO(1 0.000 0.001 0 ~ 0 {E I 0(18 010 uivalent Nb ~ 0 t 001 t I . 0.000 q , .
con .
en y Com obi I 0.002 0.017 ; 0.017 ' 0 0 ~ i 0.002 i 0.003 012 002 ~

positiongheath, alloy0.001 0 I O . .
powder) , I 0.001 001 OCI1 i I ( 0 . . 0.001 0.001 (% v . I
by O

mass)V ~ E 0.003 0.005 f O.D12 i 0.0150.003 ' I 0.004 ! ( 0.005 ~
I( guivaient i , I
V content) ~T ~ ! O.OD~. 0.006 0 0.005 ( i 004 .013 ' 0.018 ~
~

I,B (Sheath, _ .
alloy powdery _ I O.OOD ' 0.000 0_000 ; O
ODO
f . 0.a00 i .
.

! 0.0D9 0.009 0.007 0.000 I {Eguivaienf I
8 content) 0.007 0.007 0.007 I iTotai II 0.007 0 0.009' ( ~ 400 0.009 I 0.007 i 0.007 0.007 N I 0.015 f .
! 0.016 0.014 0 ~ 010 0.014 I
0.014 ( 0.014 I Mg j 0.846. p.704 .
! 0 ~ I 1 0.599 169 !
0.704 0.744 I

-i 0.000 ~ _ .
D.OOD I 0 ~D.000 000 0.000 !
0.00 0 0.000 I

1i0, J 66.474 _ .
; 7.750 5.967 6 f 494 5.083 5.967 I
5.489 ~

SiO, ( 0.457 0.849 .
~I 0.409 1.558 0 ~ 234 0.349 -i I
0.401 ' AI,O, f 0.927 O.D75 .
I 0.090 I 0.088 0 0.075 062 I
0.073 o.DOD ~ 0.040 0.000 .
I D
o.aoo ooo ~
D.DDO
.
D.ooo d,10 0.000 0.000 .
I 0.000 ~ ~ 0 0.000 000 I
(7.000 I
0.000 I V, ~- ' 0.006 0.008 .
f ( 0.007 I ~ 0 N 0.021 006 I I

.008 ~
0.026 ~ b0 _ .
0.000 O.ODD 0.002 ~ 0 j 0.011 000 ! I
0.002 !
4.014 I

.
i Na,O I 0.459 0.044 0 ~ I 0.053 .044T1).044 012 i 0.044 g' K,0 0.447 0.035 .
0,041 i 0 0.036 028 I
0.035 0.035 Ca0 0.000 0.000 .
i 0.000 0.000 0 17.000 000 I
O.OOa j B,0 I 0.029 0.024 .
0.029 0.024 0 ' (7 000 4.024 I

~ __ .
NaF 0.000 _ 0 I 0.000 D.D00 000 O.OOD
I
0.000 I

aIK2SiF, ~ . .
4.322 4.322 0.268 ) _ . 0.233 a ;CeF, I .
0.000 ' 0.000 .
.

.
. 0.000 F .
l 0.000 ~ _ O.ODO i I 0.000 I
O
ODO
O pp!

, i . 0.000 ~
~
.

!
i "i(EquivalentFcontent) 0.139 0.120 I D.t67 0.167 i ~ 0.139 ~
4.139 0.139 I

I 0.112 0.119 0 Other 0.023 004 elemenis ' ~
0.013 O.D10 j 0.023 ' Total 221 238 .

dN
;

Table 5 Wire I ComparativeC
ComparativeCompara8veComparativeC~nparativeComparative No. ~ omparatNeexample~exa exampleexampleexample - . examexam 18 E' 20 21 22 Sheath la 1e 8 ie ~ --B B
uali 16 17 13.0 19 ~ 15.5 14.0 Flux ~ B 8 7,189 15.0 7.502 1.fi85 ratio 13.0 13.0 13.0 7.260 / 7,~2 7.085 7.267 b mass Slagtomning material content /
b mass [-C . 0.D40~ 0.0400.039 0.040 0.044 t 0.0450 Si 0.3~ 0,329 0.321 0.362 0,383 0.394 .
j 0.359 -Mn l .2031.204 1.166 1.1 1.056 1.080 j 1.236 i55 0.007 0.007 0.007 0.007 0.007 0.007 O.U07 I

S 0.004 0.004 0.005 0.005 0.005 O.D05 0.005 j I j Cu 0.010 0.010 O.D10 O.D1~0 0.010 0.010 0.010 . 0.010 0.010 0.010 0.01 0.010 0.010 0.010 Ni ; ~ I
I l Cr 1.15'!1.157 1.102 1.377 1.356 r _ l ~ 1.392 1.281 l Mo 0.38110.384 0.384 0.384 0,443 O.d57 0.413 A1 Sheath, 0.007 0.010 0.00 0.007 0.007 0.007 0.007 alto wrier I 7 ' 'v jE~uivalentAl0.039 0.033 U.035 _ 0.040 ~ 0.0410.294 ~ content) l ~ D.035~

Total 0.04,5_;0.043_ 0.042 0.042 0.047 l O.DdB0.301 ~

n 0.001 0 001 0.001 0.001 0.001 O.ODt O.U01 2 ~ ~ I

j 0.00 0.002 O.OD2 0.002 0.002 0.002 Nb j l Sheatfi, 0.000 .ODO 0.000 O.OOD O.OOD
alto I 0.000 ~ 0.000 , ~ , ~ ~
NbZOz _.._ ~
E
uivalent Nb content) I

Cue- 0.002_0 002 0._0020.000.002 0.002 0.002 ~ ; 0.001 I ~ 0.001 0.001 Total 0.001 I 0.001 0.001 l ' t 0.001 l position 0.003 I 0.003 .D02 ~ .003 l V .003 :
(Sheath, ~ O.OD3 all l 0.003 ovvder I
n r ~
I
U,C)Z
mass) I
V
(Equivalent V
content) ~

,, 0.004 0.004 0.004 0.004 0.004 0.003 I, I 0.022 ; 8.004 ! 0.000 Total 0.000 j 0.000 1 0.000 ~ j ~ 0.000 j8 0.000 (Sheath, alloy ponder) j B U~022 0.001 U.005 0.006 0.007 0.008 0.008 I(EquivalentBcontent) ~ ; I l iTotai 0.022 0.023 0.006 0.006 0.007 0.008 0.0~
I ! l l I I j N 0.010 0.010 0.003 O.D37 0.014 0.013 0.015 ! _ ( M 1.169 1.169 0.519 0.519 0.180 1.517 0.657 I ' I .

' 0.000 0.000 0.000 O.ODO 0.000 0.000 0.000 ~ I I l ~ ; j Ti0? 6.494 fi,494 6.494 6.494 fi _. I ; j 459 6 674 4.126 . ~ j I,j 0.439 0.241 0.296 L 0.2960.341 0.352 2.258 SiO, 1 j j . I
'.

AI,O, 0.074 0 062 0.066 0.066 0.075 0.078 0.556 I I I ~ I

0.000 O.OOD 0.000 0.000 0.000 0.000 0.000 j l I

M 0.000 0.000 0.000 O.D00 0.000 0.000 0.000 0 l I ' ' I l !

V,0 0.008 0.006 U.006 _ 0.006 0.006 O.OD4 ; ~ ' 0.006 ~
~

y 0.000 0.000 T0.0000.000 0.000 a.oao O.ODO
Nb,O~ l I

Na,O 0.101 ~ 0.0150.039 _ 0.044 0.046 0.287 ~ 0.039 j I

K,0 0.035 0.028 0.030 0 U.035 0.036 ~ 0,198 ~ j 0317 !

~ 0.000 0.000 0.000 _ 0.000 0.000 0.D00 l 0.0017 !
Ca0 B,0 0.069 0.002 0.021 0_.021 0.025 0.025 ' O.D00 , 0.000 0.024 I 0.000 N~ ~ - 0.0000.233 ; 0.000 0 I 0.2_33~ I O.OOD 0.277 250 ~~K~SiF, ~ 0.233 0.000 l 0.2330.268 ~ 0.000 O.ODO 0.000 U.032 0.000 0.000 .
~ l I l I 0.000 ~CeF, _ !
CaF> 0.000 O.D00 0.000 _ 0.000 0.000 x I 0.038 0.000 l Total 0.120 0.120 0.120 0.14!3 Ce.139_ _ Equivalent 0.144 0.130 F
content Other 0.012 0.004 0.006 0.013 0.008 0.008 0.082 elements I j Total ! ~
TdN
j -3'! -Table 6 Wire ComparativeComparativeComparativeComparativeComparativeComparativeComparative No.

exampleexampleexam exam exampleexam ; exam 23 24 7e 7e 21 7e Ie Sheath ~ g g ~ B B ~ B B
ualitv l Flux 14.0 13.0 16.0 16.~ 14.0 18.0 14 ratio 0 ~/o b mass .

Slag-forming .
material content 8.002 7.644 8.848 7.744 6.874 8.694 8.035 /o mass ' C 0.034 0.040 0.046 0.047 0.042 0.047 0.041 _ Si 0.367 0.332 0.395 0.049 0.360 0.325 0.343 I

Mn I 1.2301.165 1.266 0.502 I- 1.1401.033 1.275 0.006 0.007 0.007 0.006 0.007 0.007 0.007 S 0.005 0.004 _0.005 0.005 0.005 0.005 ! 0.004 Cu 0.010 _0.0100.010 0.010 0.010 0.010 0.010 !

Ni 0.010 0.010 0.010 0.010 0.010 0.010 0.010 Cr 1.356 1.178 1.396 1.378 1.281 1.153 1.292 no l O.d'130.384 0.472 0.47 0.413 0.531 0.413 AI Sheath, 0.0:3 0.007 0.007 O.U07 0.007 - 0.4fi~0.007 all ' ~ ~~0' 0.029 0.035 0.042 0 0 0 ~ ~

. . . 0.042 E uivaientA!
content Total I 0.042 0.042 0.049 0.050 0.139 0.513 0.049 r ~ 0.001 0.001 0.009 0.001 0.001 0.001 0 ; , 001 I iNb Sheath, 1 0.0020.002 0.002 0.002 0.002 _ .
aN ~w~ I 0.002 0.002 !

Z

Nb, E 0.000 0.000 0.000 0.000 0.00 0.000 0.000 ~~alent Nb content !Total 0.002 0.002 r 0.002 O.OD2 0 0 j l 0.002 l 002 002 positionV (Sheath, 0.001 0.001 O.OOt 0.001 _ .
~ alloy powder1 ' O.G01 0 0 I~ I 001 001 I

% ' ~ _ _ . .
O ~

l ~ j EZ "'004 0.004 0.004 0.002 0.004 0.004 may uivaientVcontent 0.003 t I l l I

Total ' 0.045 0.005 0.003 0.005 0.005 l ~~
0.005 0.004 ~B (Sheath, 0.400 0.000 X0.000 0.000 0.000 0.000 ally ) ; ! l I
0.000 ~

B=O1 _ B ( 0.008 0.006 0.007 0.008 0.008 l E uivalent I ! 0.008 B conte~_nt~, ~ , ~

'Total I O.Q08 0.006 0.007 0.008 0.008 0.023 0.008 j ~

N ; 0.013 0.012 0.014 0.015 0.0 0.038 1 ! 0.014 j 38 ~ug ! D.sSS o.slo o.s39 o.s57 _ 1.25s I I 0.799 f 0.845 I ~ . o.ooo o.DDD o.ooo D.aoo a.DaD o.DOo I D.DOO I l TiO, ! 8.322 7.143 7.193 4.126 6.993 . I 6.889 I 7.750 SiO, 0.271 0.289 0.355 1.042 0 ' l 0.363 l 0.399 .473 f l AI,O 0.055 0.065 0.080 0.249 _ I ! 0.080 0.090 _ I ~ 0.079 zro, D.ooD o.aoo o.aoo o.ooo o l o.oD~ a.ooo ooo I M 0 0.000 0.000 0.000 0.000 .
I 0.000 0.000 0.000 !

V,0 ~ 0.007 0.00 0.006 0,004 0 6 I 0.005 I 0 006 'I

y Nb,Os 0.000 _ 0.000 _ .
0.000 I O.ODO . 0.000 0.000 ' 0.000 I

Na,O j 0.046 0.036 0.044 0.103 E I 0.047 I 0 f 049 : 0 K 0 I 0.019 0.030 0.03 .
0_p37 , 0.085 l 0.041 Ca0 ) 0.000 0.000 0.000 .
0.000 0.000 0.000 l 0.000 0.025 0.019 0.023 0.025 0.026 0.026 0.075 INaF 0.000 0.000 0.000 0.606 , 0.000 0.000 0.000 a ~K,SiF 0.039 1.097 0.557 _0.250 ' _0_.28fi ~ 0.322 ! 0.250 o CeF ~ 0.000 0.011 ~ 0 0.000 000 I 0.000 0 000 ' 0.000 I ~ ICaF, ~ 0.000 0.000 0.000 0.
-- 0.000 000 0.000 l 0.000 _ ' s T ~ _ l _ nalent F content 0.023 0.568 0.562 ~ 0.930 1 0.148 0.167 ~ 0.130 " ~ E u l Other elements 0.007 0.013 0.018 0.006 l 0.0()9 0.009 ! 0 Totalli/N 384 348 298 .

Table 7 Wire Exam Exam _Exa_mExam Exam Exam Exam No. ale 7e 1e 7e 1e 7e !e t 2 3 4 5 6 7 , ~

Sheath A B B B~ g ~ B
uali Flux 15.9 15.9 _ 18.0 18.0 13.0 14.0 ratio 15.0 ~
r6 b mass Slag-funning 7,260 7.260 7.245 8.910 8.910 6.565 7.149 material I
content ~o b mass I C 0.?70 O,D35 0.037 0.044 0.043 0.035 0.036 Si 0.487 0.073 0,841 0.417 9.271 0.357 0.379 ~ !

Mn O.fi401.217 0.817 0.569 1.573 1.008 1.07d ! 1 P 0.012 0.006 9.007 9.007 0.007 O.OD7 0.006 ' S 0.007 O.OD5 D.ODS 0.005 0.005 0.005 0.005 [ ~ ( Cu O.Oti 0.090 0.010 0.0t0 ~010 0.010 0.010 ~' ' Ni O.D12 0.010 0.010 ~ 0.010 D.O1D 4.010 0.010 Cr 1.125 1.293 1.294 1.548 1.548 2.524 0.113 [

Mo 0.380 0.443 0.443 0.531 9.531 9.978 ~ 9.466 I I

AI 0.033 0.007 0.022 O.OO~ O.OD7 O.p08 0.007 f AI o.oac)D.o4D p.oao 0.04a 0.048 0.035 0 ~' ~ ~ 038 E .
uivalentAl content Total 9.073 0.047 0.062 O.paS 0.055 0.043 0.045 ~ ;

Ti ~ O.OOa O.OD1 9.002 0.001 0.001 O.DD1 0.001 [ ( ) j !

INb 0.002 0.002 0.002 O.OD2~0.002 9.002 0.002 I I .
w INb -t --2 O.OOD O.ODO 0.000 0_090 0.000 O.ODO O.OOD
j , 1 ~ I , E uivalent Nb content 0~- Totai ' 0.002 0.002 0.002 0.002 0.002 0.002 O.D02 ~ [ I

position ~V O.OD1 9.001 9.001 O.DO1~0.001 0.001 O.OD1 . I " ;

%b y VZO' 0 1 I ' ' V 0.0 O.D03 0.003 0.004 0.004 9.003 9.903 m~1 ~Eauivalent 8 ~ , _ V content Total I 0.004 0.004 O.OD4 0.005 W).D05 0.004 O.D04 I ' I

B G.ODp O.OOD O.ODO 0.040 9.000 0.000 0.000 1 I ;

IB

B' 0.007 0.007 0.007 O.p0:9U.009 0.007 ~ O.DOl ' ( 1 ~
Equivalent B content) !Total 0.007 0.007 0.007 I 0.0090.009 0.007 0.007 ! N [ 0.012O.D13 0.013 0.015 0.015 0.011 0.015 M ! 0.5990.599 0.599 0.719 ! 9.1190.519 0.559 I [

Zr 0.109 I 0.033; 0.0330.26'1I 6.163I 0.1180.127 i0, L ! 1 . ' I

[ 0 ' 0.34 0.34 ' 0.4&7I 0.4670. 0.324 sio~ ~ 0 ~
~

AI,O, 0.075 0.075 0.07 5 0.099I 0.099I 0.9660.071 ZrO, 0.000 0.000 1 0.000; 0.2990299 0.129 ~ 0.139 ' M 0.000 0.000 0.900 O.DODi_ ' 0.2501 0.269 0 I I T 0.000 V ? ODDS! 9.006I D.D05I 0.0070 007 0.005 O.ODS
0~

I y Nb,O O,DpO O.OOp 0.000 0.000 D.OpD O.OOD ! 0.000 Na,O O.p44 0.044 ' 0.0440.053 0.053 O.D39 0.041 K,0 0.035 ~ 0.035I 0.0351 0.04i~O.p41 ; 0.030 0.032 Ca0 ! 0.0000.000 j 0.0000.000 ~ 0.000I 0.003 ~ 0.003 8,0, I 0.0240.024 ~ O.D24; 0.029I 0 0.022 029 0.023 ~NaF 9.000 O.p00 0.141 0.169 ' 0 ! 0 . .
.

a 0.268 0.268 0.119 0.143 0.1~ 0.193 K,SiF 1 I
0.111 a ~ 0.0000.000 0.374 0.00 0000 1 0.000 CeF 0.058 .~ O.DDD t O.D00DODO 0.035 9.035 0.025 CaF, - + v 0.027 V-1 I ~
~ ~i Tota~I

_ 9.139 0.139 0.234 , 0.1681 0.168147 "

I Eauivalent ~ .
F
content 1 Other O.ODB 0.008 0.093 0.022 0.022 0.016 elements 0.029 Total j 320 ' 301 281 ; 306 ~ 307 286 _33_ fable $
Wire Exam Exam Exam Exarn E:xamoleExam Exam No. 7e 7e 7e 7e 12 (e 7e - 8 9 10 ti~ ~ 13-' 14 ~

Sheath _A B B 8 f B 8 , B
uali~-Ftux 17.0 16.0 16.0 13.0 15.5 15.5 15.5 ratio o b mass S~a g_g36 8.272 8.368 7. 7.549 7.564 7.564 gb-fom l S ~ ~
i~ng t material 1 content C D.O6_40.048 0,047 0.040 0.045 0.045 0.046 ~

Si 0.462 0.624 0.536 0.404 0.526 0.393 0.532 Mn 1202 1.379 1.379 1.077 1.343 1.228 1.228 ) P 0.011 0.007 0.007 0.007 0.007 0.007 U.007 I ' S 0.008 0,005 0.005 0.005 0.005 0.005 0.005 Cu 0.011 0.010 0.010 D.O10 0.010 0.010 0.010 Ni 0.012 0.010 0.010 D.D10 0.010 0.010 0.010 ~ ' Cr 2.482 1.445 1.278 1.158 1.280 1.214 1.354 Mo t .0680.472 0.472 O.d08 0.457 0.457 0.457 A1 0.032 0.167 U.Q07 U.OD7 0.008 0.00 0.00 f _ _ _ _ ~ 0.04& 0.295 O.D43 0.033 0.041 _ _ I ~ ~ ~ 0.041 0.041 EauivalentAl ( content Tota! 0.078 0.462 0.050 O.U41 0.049 0.050 O.OdB
I ) ' ' ' ~'~' T 0.072 0.068 0.068 0 ~_ 0.066 0.066 I O.U 0.286 I

: Nb O.OOZ 0.002 0,003 0.002 0,002 0.002 0.002 : ' ) !

Nb,O, Nb~E uivalent O.DDO O.ODO 0.003 0.000 0.000 0.000 0.000 Nb content , Total o.oG2 O.oD2 O.OOS o.C02 0.002 O.ao2 0,002 - I I

position ~V 0.001 _ 0.001 _0.0_01_0.001I 0.001O.OOt O.OOt ' ' .

mass) V EOuivafent O.OU4 0.003 0.007 0.003 O.D03 ~ 0.0030.003 ~ I V content ( ~

~ Totai 0.005 O.OD4 0.008 O.OOd 0.004 0.004 0.004 J

B f D.DDD o.DDD O.ODO O.ODO 0.000 ) 0.0000.000 ~ I I I

8 B20'. 0.009 O.D08 0.008 O.OD2 0.008 ~ 0.0090.009 f ~ : Eouivalent ~ j 8 contenty ~~Totaf ~ 0.0090.008 0.008 0.002 O.D18 . 0.0D90.009 f ) I 1 N 0 0.014 0.019 0.007 0.023 ) 0.0060.033 .093 ~

M _ 0.751 0.751 0.2 _ I 0.728_ 0.849 0,728 j~
0.728 Zr 0.1:4 0.145 0.116 f 0.000; 0.1120.028 I 0.112 T0, 7.133 6.889 7.135 6.494 5.674 f 6.67dI 6.674 ~

I ~ 0.394; 0.3630.384 ) 0.255; 0.352I 0.3600.360 SiO, r ~

'_ 0.086 0.568 0.080 ~ _0_.0630.078 0.078 0.078 AhO, Zr0 0.168 O.OUD 0.000 I O.OU_00.000 ~ O.OODf 0.000 ~ I

M 0.326 0.000 0.156 I O.OUO0.000 0.000 ! U.000 j ,V,0 0.006 0.006 0.012 O.OU6 t U.DO6 I 0.006 ;
0.006 yNb,O O.OOU ) O.D000.004 O.OOD U.000 0.000 ~
0.000 ~I 0.050 0.049 0.047 0.021 0.046 I 0.049 Na,O 0.049 K,0 0.03.90.037 0.037 f 0.028~ 0.036 ~ O.U36 0.036 Ca0 0.004 0.000 0.002 I 0.0(10I 0.000 ' 0.000 I O.OUO

"'B 0.028 0.026 0.026 O.OU7 ~ 0.025 ; 0.028 0, ~-0.028 ~l 0.160 0.000 0.000 O.ODO 0.000 I 0.000 ~ +
NaF 0.000 ~ 0.135 ~ 0.2860.286 0.233 0.277 ~ 0.277 ~ j K,SiF 0.277 a 0.042 I O.OdOO.ODD O.DGO O.D39 0.039 CeF 0.039 ~ 0.033 O.OOD 0.15fi ~ 0.00O.OOD ! 0.000 ,CaF 0 0.000 -' 0.171 I 0.1600.224 _ c).155 0.155 To~l 0.12U ~
I 0.155 E
uivaient F
content I 0.03C ~ 0.0170.042 0.005 0.016 0.917 Other 0.017 f elements I 328 291 : 233 539 184 I 125 Total 679 TdN

Tat~le 9 Wire ExampleExam am Exam Exam Exam Exam No. t ie 1e ie 1e 1e 1e 5 16 t t 19 2D 21 . ' 7 8 '' Sheath ~ A ~ ~ 8 B 9 B
uali ~
B

Flux 15.5 15.5 15.5 15.0 16.0 1 1&.0 ratio i ~ 6.
, 0 mail Slag-forming ~ _ material 7,649 7.502 7.146 8.730 7.512 _ 6.256 content _ _ ~ 8.592 ~
b mass) C 0.040 0.060 0.044 0.043 0.046 0.046 D.049 ~

Si 0.556 ~ 0.38 0.354 0.342 0.396 0.396 D.365 _ Mn l.lfig1.124 1.228 1.192 1.268 1,265 1.150 P 0.007 0.011 0.007 0.007 D.007 0.007 0.007 I

S _0_.0U5_0.007 0.005 0.004 D.005 D.005 0.005 ___ _ Cu 0.0'0 0.011 0.010 0.010 0.010 0.010 0.01D

Ni 0.010 0.012 0.010 0.010 0.010 0.010 0.010 Cr 1.351 1.362 1.280 1.239 t.396 1.396 1.321 I

Mo 0.457 0.460 0.457 0.443 0.472 U.472 0.452 AI O.OD7 0.032 0.007 0.007 _0.007 0.001 D_007 AI~0' - ~ 0.041 0.041 O.D47 0.032 0.043 0.043 0.042 uivalentAl content) Tota! I O.a48 0.073 0.054 0.039 0.050 0.050 0.049 Ti 0.163 0.033 D.D98 0.1'260.034 0.2U1 0.034 I i i I

!Nb _0_.0020.002 0.002 O.OD2~0.002 0.002 0.002 , i NbiNb20' 0.001)0.000 0.000 O.aOU 0.000 0.000 D.D00 ~(Equrvaient ~
Nb I
content) ~

Cue- !Total 0.002 0.002 0.002 O.Ot)20.002 0.002 0.002 i I I

post6on IV O.OUt 0.001 0.001 O.OOt 0.001 0.001 0.001 4 I i ' mass) V 0.003 0.003 0.002 O.D03 0.003 0.003 ~ ' ~ ~ ~
~E i O.OD4 uivalent ~
V
content) ~
~

iTota 0.004 0 04 0.0D3 0.004 0.004 0.004 I 1 i f O.ODS

.B O.ODO O.aDO 0.000 i 0.0000.000 0.000 I ~ ! ~ ~ ;
0.000 9 I O-0080.008 ~ 0.009 ~ 0.0080.008 .
i ~ ~ ( 0.008 (Equivalent 0.007 B
content) i jTotai ~ 0.008D.a08 0.009 r 0.0080.008 0.008 I ! 0.C07 N 0.008 0.007 0.023 0.015 0.014 0.024 0.023 M 0.232 1.487 0.728 0.761 i 0.70.4 ~, !
0.751 0.799 i o . o.aooo.o ~LOOO o.ooo a.oDO~
zr .t op 12 a .DO
i i _ ! 6.674_ 6.889 f 6.8895.355 i0, _ _ 6.674 _ _ _4.336 ~
8.01 0.352 0.352 0.851 0.363 _ 0.363 0.280 0.364 AI,O, 0.078 0.078 O.a89 ).080 0.080 0.080 ~ ' 0.00_00.000 ! '0.000 0.000 O.DOO
ZtO,~ 0.06( r 0.936 I
0.000 I M 0.000 0.000 0.455 i O.OOU; 0.0000.000 I O.OUO

V,t)< I 0.0060.006 ' 0.004I 0.0070.006 0.006 0.005 N 0.000 0.000 0.000 I O.D00i O.D000.000 i 0.000 Na,O 0.046 0.046 0.052 ; O.a41 0.047 t O.Q47 ;
0.047 K 0.036 0.036 i 0.041i 0.027 0.037 0.037 Q 0.037 Ca0 A 0.000t O.UOD0.007 0.000 0.000 0.000 0_000 ~

0,o, o.o2s o.025 o.o2e ~ a.oz4 o.o2s o.o2s ;
o.o2s -~ ! 0.0000.000 _0.o_00I 0.000 0.452 0.000 I_NaF O.OUO

zjK 0.27_7~ 0.2170.277 0.268 ; 0.5570.286 SiF !
0.048 o 0.039 0.C00 I O.a390 0.040 0.040 CeF, .000 ~ 0.000 0.000 0.000 _ _ 0.000 CaF, ~0.000~ ~ 0.047 iTotaf 0.155 0.144 0.155 ~ 0.139 D.527 0.160 E 0.027 uivalent i F ~
content Other 0.016 0.008 0.032 0.005 0.047 0.018 elements 0.009 Totaf 287 I
TiIN

- a5-Tabis .0 (Wire ~Vo. ~ Example 22 Example 23 Exam ie 24 Exam I~ a 25 , Example 26 I
Example 27 ' Example 28 Sheath quali l 8 C O C IC I C
A ~ 8 Flux ratio % b mass ~ .0 15.0 17.0 ? 5.0 12.0 16.0 14.0 Slag.forming material content b mass 9.'20 7.26D 7. 7 01 6.793 6.636 7.744 6.804 C 0.054 ~ 0.049 ~ 0.051 0.048 0.043 0.068 0.043 S~ 610 0.563_ ! D.434 0.493 0.453 0.368 ! 0.447 ~ 1..?57 j 1.275 1.29_3 1.275 1.246 0.974 0.9_84 ' P O.t107 0.004 0.004 0.004 0.003 I D.012 0.007 S 0.0_05 D.007 0.007 0.007 ; 0.001 0.007 0.005 Cu 0.009 0.011 I 0.011 ~ 0.011 0.011 D.011 0.01(7 Ni 0.010 0.043 0.042 0.043 0.044 0.012 0.010 Cr ! 1.483 1.269 1.253 1.341 1.293 1.522 I 2.250 Mo ~ 0.508 0.502 ~ 0.5D5 0.502 0.498 O.S05 l 0.8_78 AI 0.007 0.004 0.004 ~ 0,004 I 0.004 0.032 0 07 l AI ~q NaientAl content Ova l 0.040 0.045 l p,040 O.D32 D.043 ~ 0.037 Total O.Qd5 0.044 0.049 0.~ 0.036 f 0.075 l 0.044 0.114 0.002 0.144 0.1_27 I O.OD2 ~ 0_001 I 0.001 eNb I 0.002 0.002 0.002 0.002 ~ 0.002 0.002, 0.002 !Nb20, I Nbi(Equivaient Nb content) [ O.DDO 0.000 0.000 0.000 0.000 0.000 ~ D.000 ;Total ~ 0.002 0.002 I 0.002 D.002 0.002 I O.OD2 l 0.002 position IV 0.001 l 0.003 0.002 0.003 0.003 ! 0.001 . 0.001 -.-~
(% by V 0 mass) ,! V (Equivalent V content) 0.004 f 0.003 0.003 ~ O.D03 0.003 I 0.003 0.003 ( Total l O.ODS j 0.006 0 005 ; 0 _006 I 0.006 0.004 I 0.004 l O.OOD I O.OOD ! 0.000 ~ 0.000 0.000 I 0.000 ! 0.000 I
I 8 I (Equivalent 8 content) ~ 0.009 ~ 0.007 ~ 0.008 0.007 0.006 0.0018 0.008 ~Totai 0.009 I 0.007 0 008 l 0 OD7 0.006 j 0.008 j 0.008 !
! I 'y _ 0.02_7_ ; 0.018 ~ D.019 ~ .
I 0.027 I 0.016 j 0.023 0.019 Mq - l 0_899 ( 0.674 I 0.764 I 0.674 I 0.539 I 0.799 0.699 0.000 I 0.081 0.000 ~ O D27 ; 0.000 I 0.000 0.000 TiO, l 7.912 ! 6.459 6.793 ~ 5.994 I 5.994 6.889 5.594 SiO, ~ 0.624 ; 0.341 I 0.386__! 0_341 . D273 I 0.363 I 0.374 Ai,O, j _0.071 r 0.075 0.085 0.0_75 ~ 0.061 I 0.080 0.071 l Et0= ~ 0,604 I 0.000 0.000 I 0.000 ! _ 0.000 0.000 0.094 Mg0 ~'1 0.000 0 ODO I 0.000 p 0_00 I 0.000 I 0.000 ~ 0.133 I
~ ~ ~~s I 0.007 j 0.006 I 0.006 I D.005 I, O.ODS ~ 0.006 I 0.005 j Nb,O. ~ O.OGO r 0.000 I 0.000 j 0.000 0.000 j 0.000 O.Q00 I
I
Na,O~ 0.050 0.044 l 0.050 0.044 0.436 I 0.047 I 0.046 K,0 ' 0.033 ~ 0.035 l 0.039 O.D35 I 0.028 0.037 I 0.030 Ca0 - _ . O.OOD j 0.000 0.000 O.D00~ 0.000 0.000 0.002 I ~ I
0.029 ! 0.024 0.027 0.024 0.019 l 0.026 0.025 INaF 0.000 I 0.000 0.000 0.0_00 1 0.000 0.000 0.013 aIK,SiF 0.322 0.26$ 0.304 0.:?68 ~ 0.215 0.286 0.250 o ~CeF ~-- 0.045 0.000 ~ O.ooo j o 000 - 0.000 O.ooo o.lls ~ caF, D.ouo o.ooo ~ o.ooo o.ooo ~ D.ooo I o.ooD 0.014 _° Total " E uivalent F content 0.180 ~ 0.139 0.157 ~ 0 139 0.111 j 0.148 0.176 Other elements 0.0:24 0.008 D.010 0.(708 ~ 0.006 0.009 I 0.035 Total TiIN 183 I 215 ! 218 1:38 225 178 ' 172 _~s_ Table 11 Woe Exam Exam Exam j Exam j ExamExam 7e 34 No. !e 1e 7e 7e 1e ~ Exam 7e _ 29 30 31 32 33 35 ' Sheath ~ g B D D g uaii _,_ _ g "- ; 15.015.0 15 16 14 1 Flux 5 0 0 ratio /
b mass . . . 13.0 15.0 Slag-fanning material content % 1.290 7.245 7.487 7.216 ~ 6.3147.215 8.325 mass C 0,051 0.059 0.062 ; 0.0550.052 0.044 0.050 Si 0.663 0.461 _0.5180 0.465 0.471 ~ O.6D6 .463 Mn 1.037 1.035 _1.062_ 1.232 1.236 1.240 1.251 1' 0.007 0.007 0.007 _ 0.007 0.007 0.007 _ 0.007 S 0,005 0.005 ~ 0.005T 0,0050.005 0.004 0.004 ' Cu 0.010 0.010 0.009 0.012 0.012 0.0 10 0.010 I [ 0.0100.010 0.010 ~ 0.0260.027 _ Ni 0.010 ~ I
0.010 Cr 2.338 2.338 2.416 2.134 2.173 1.178 ~ 1.282 ~

Mo 0.940 0.940 0.972 0.994 ~ 1.007_ ! 0.400 [ 0.462 AI O.OD7 0.007 O.OD7 0.002 O.OD2 0.007 0.007 ;

~0 ~ ivalentAl 0'0'400.439 0.041 0.042 0.036 0.035 0.041 content ( ~

Total 0.047 0.046 0.048 0.044 0.038 0.042 1 0 Ti 0.001 0.126 0.130 O. t 0.001 .
I I I 35 0.001 [ O.

Nb 0.002 0.002 O.OD2 0. 0.002 0.002 1 0.002 I

0 _ I
Nb ~ , 0.000 O.DDD 0.000 O.OOD O.ODO 0.000 f 0,000 2 I ~ ~
Nb Equivalent Nb content - ITota! 0.002 0.002 0.002 0.002 0.002 0 j I 1 002 0 I I 0.001 0.001 0.001 0.003 0.003 .
position V ~ ; ~ .

00 t 0 %b .
V .

mass) ~Equi-va-le~nt 0'003 0.003 0.003 0.00 0.003 0.003 ~~
0.004 V ! ~
content ( ~

Tota O.Oil40.004 0.004 0.006 0.006 0.004 ~ 0.005 1 I j g o.aoo a.ooo D.ooo D.ooD 0.000 0.000 0.000 ~ I j g ,(Equivalent9content) 0.008 O.OD6 0.006 O.DO6 0.005 0.008 I 0.009 1 I ~ 1 ~ ~ ' . _ I,Tota! O.ODS O.OOfiO.DO6 0.005 0.008 1 0.009 j I ( ' I
0.006 1 N 0.021 0.021 0.018 0.017 0.010 ; 0.010 I I ;
0.021 ~ D.7~i9 0.774 0.799 1.273 I 0.749 9 I 0.699 0.749 ~ 0.136 0.028 0.029- 0.094 0.163 a 1 1 0 1 0.000 X25 [ j TiO, 5.994 6.194 6.394 6.494 ! 7.493 I 1 ' ~ 5.594 5.994 [

SiO, 0.401 0.390 0.34 0.309 0.357 ! ! , 0.304 0.378 AI,O, 0.076 0.077 0.(179 0.066 j 0.077 0.074 I I 0.069 f 1 ' ~ 0.1040.000 0.000 ~0, ; [ 0.000 0.000 .
0.101 .
0.101 Mg0 0.148 0.000 _ 0,143 l, 0.000 j j 0.000 0.000 0.143 V,0< 0.006 _ _ 0.005 I 0.006 0.006 ~ 0.007 I 0.005 0.005 Nb,o D.ooo o.aoo o.DOO 0.000 0.000 0.000 ;
o.ooa Na,O 0.041 0.042 0.044 ' 0.051 0.054 I 0.037 0.040 I

K,0 0.032 0.(I~ 0.030 I
0.032 I 0.029 0.035 ' 0.031 Ca0 0.002 _ _ . 0.000 0.000 I 0 0.002 ' 0.000 000 ~
O.DD2 ~ 0.020 0.020 .
8,0 I I 0.017 0.025 I 0.029 I ' 0.027 ~
O.Ot9 jNaF 0._0150.000 0.000 ~ 0.000 __0.014_ 0.000 : 0.277 0.233 I
a 0.286 0.268 K,SiF~ I
0.268 0,250 0.129 _ I 0.000 0.000 '~ 0.000 I 0.000 o CeF, 0.125 0.125 CaF, 0.015 0.000 ! 0.
_ 0.000 0.015 0.000 0.01 S

1 I 'w a Totai 1 ' 0.195 0.120 0,139 "' 0.148 ~
' 0.130 (Equivalent F_content !
0.189 0.188 !

1 0.038 0.007 Other 0.00 0.008 elements 0.008 I I
O.D38 0.037 Total 181 400 1 450 T'~N 215 ~

~ ' 'L' a o o ~
I

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Results of the test using the flu:-cored wires in .examples and comparative examples will :be explained.
The flux-cored wire in Comparative example 1 has a C
content exceeding 0.20 by mass, which is the upper limit C
content specified by the present invention. Hot cracking occurred in the weld metal formed by using the flux-cored wire in Comparative example l, and the weld metal had an excessively high tensile strength and could not meet rec[uired impact performance.
The flux-cored wire in Comparativf~ example 2 has a Si content smaller than 0.06 by mass, which is the lower limit Si content specified by the present invent=ion. The weld metal had insufficient viscosity, unacceptable convex beads were formed by vertical-position welding. Blow holes were formed in the weld metal due to insufficient deoxida.tion. The weld metal had a low toughness due to low B recovery and could not _4g_ meet the required impact performance. Sufficient TiN that suppresses ferrite band could not be precipitated due to the insufficient reduction of TiOz and ferrite bands were formed in the weld metal.
The flux-cored wire in Comparativ~a example 3 has a Si content greater than 1.10o by mass, which is the upper limit Si content specified ~>y the present invenirion. The weld metal had an excessively high tensile strength., and the weld metal could not meet the required impact performance due to the reduction of toughness because of the solid solution of Ti increased due to the excessive reduction of TiO~.
The flux-cored wire in Comparative example 4 has a Mn content smaller than 0.55 by mass, which is the lower limit Mn content specified by the present invention. Although the usability of the flux--cored wire was satisfacteory, blow holes were formed in the weld metal due to insufficient deoxidation, and the tensile strer~gth and the 0.2o-o:=fret yield strength and the toughness of the weld metal were low due to insufficient hardening and the small B recovery. The weld metal could not meet required abilities corresponding to those properties.
Sufficient TiN that suppresses ferrite band could not be precipitated due to i:he insufficient reduct~_on of Ti02 and ferrite bands were formed in the weld metal.
The flux-cared wire in Comparative example 5 has a Mn content exceeding 1.60° by mass, which is the upper limit Mn content specified by the present invention. The fluidity of the weld metal was ex~:essively high and unacceptable convex beads were farmed by vertical-position welding. The weld metal had an excessively high tensile strength, The solid solution of Ti increased due to the excessive reduction of TiOz.
Consequently, the weld metal had a low toughne:>s and could not meet required impact performance.
The flux-cored wire in Comparative example 6 has a Cr content exceeding 2.60$ by mass, which is the upper limit Cr content specified by the present ir_vention. The weld metal had an excessively high tensile strength, a low toughness and could not meet required impact performance.
The flux-cored wire in Comparative example 7 has a Mo content smaller than 0.30% by mass, which is a lower limit Mo content specified by the present invention. The weld metal had a low tensile strength and a low 0. 2 o-offset yield strength, that is, low strength properties.
The flux-cored wire in Comparative example 8 has a Mo content greater than 1.50 by mass, which is the upper limit Mo content specified bar the present invention. The weld metal had a low toughness and could not meet the required impact performance.
The flux-cored wires in Comparative examples 9 and 10 have A1 contents greater than 0 . 50% by mass, whi ch is the upper limit A1 content specified by the present invention. The weld metals hardened and e:mbrittled, had excessively high tensile strengths and low toughnesses, respectively, and could not meet the required impact performance.
The flux-cored wires in Comparative examples 11 and 12 have Nb contents greater than 0 . 015°s by mass, which is the upper limit Nb content, specified by the present invention. The weld metals had iow toughnesses, and could ncat meet the required impact performance.
The flux-cored wires in Comparative examples 13 and 14 have V contents greater than 0 . 015% by mass, which is the upper limit V content specified by the present invention. The weld metals had low toughnesses, and could not meet the required impact performance.
The flux-cored wire in Comparative example 15 has a B
content smaller than O.OOIs by mass, which is the lower limit B content specified by the present invention. The weld metal could not be formed in fined microstructure, had a low toughness and could not meet ~h.e required impact performance.
The flux-cored wires in Comparative examples 16 and 17 have B contents greater than 0 . 020 o by mass, which is the upper limit B content specified by the present invention. Hot cracking occurred in the weld metal.
The flux-cored wire in Comparative example 18 had a N
content smaller than 0 . 005 o by mass, which is the lower limit N content specified by the present invention. Ti could not be fixated in a TiN precipitate, and the weld metal had a low toughness and could not meet the required impact performance.
Sufficient TiN that suppresses ferrite band was not precipitated and ferrite bands were formed in the weld metal.
The flux-cored wire in Comparative example 19 has a N
content greater than 0 . 035 o by mass, which is the upper limit N content specified by the present invention. Blow holes were formed in the weld metal, the toughness of the weld metal was reduced due to the increase of the solid solution of N, and the weld metal could not meet the required impact performance .
The flux-cored wire in Comparative example 20 has a Mg content smaller than 0. 20 o by mass, whic:z is the lower limit Mg content specified by the present invent~_on. Blow holes were formed in the weld metal due to insufficient deoxidation. The B recovery was low, and the weld metal had a low toughness and could not meet the required impact performance. Sufficient TiN that suppresses ferrite band could not. be precipitated due to the insufficient reduction of Ti02 and ferrite bands were formed in the weld metal.
The flux-cored wire in Comparative example 21 has a Mg content greater than J_.50o by mass, which is the upper limit Mg content specified by the present invention. Intense spattering occurred during welding. The weld metal has a low toughness due to increase of the solid solution of Ti resulting from the excessive reduction of TiO~, and 'the weld metal could _~~_ not meet the required impact performance.
The flux-cored wire in Comparative example 22 has a Ti02 content smaller than 4.2% by mass, which is the lower limit Ti02 content specified by the present invention. Arcs were unstable arid the usability of the flux-cored wire was practically unacceptable. Since the Ti02 content is small and the reduction of Ti02 was insufficient, insufficient Ti was produced. Sufficient TiN that suppresses ferrite band was not precipitated and ferrite bands were formed in the weld metal.
The flux-cored wire in Comparative example 23 has a Ti02 content greater than 8.2% by mass, whicri is the upper limit Ti02 content specified by the present inve:ation. Slag covered the molten pool during welding and slag inclusion occurred.
The weld metal had a low toughness due to a large oxygen content, and could not meet the required impact performance.
The flux-cored wire in Comparative example 24 has a fluorir_e compound content in terms of F content smaller than 0.025% by mass, which is the lower limit fluorine compound content in terms of F content specified by the present invention.
Arcs were instable during welding and the usability of the flux-cored wire waspractically unacceptable. Blow holes were formed in the weld metal due to insufficient deoxidation. The weld metal had a low toughness due to low 13 recovery and could not meet the required impact performance. Sufficient TiN that suppresses ferrite ba~~zd was not precipitated due to insufficient reduction of TiO~ and ferrite bands were formed in the weld metal.
The flux-cored wire in Comparative example 25 has a fluorine compound content in terms of F ~.~ontent greater than 0.550 by mass, which is the upper limit fluorine compound content in terms of F content specifiedby the present invention.
The fluidity of slag was excessively high, the bead covering performance of slag was unsatisfactory, and unacceptable convex beads were formed by vertical-position welding.
The flux-cored wire in Comparative example 26 has a Si content and Mn content smaller than O.OE~o by mass and 0.55°s by mass, respectively, which are the lower limit Si content and the lower limit Htn content specified by the present invention. The weld metal had insufficient viscosity and unacceptable convex beads were formed by vertical-position welding. The weld metal was insufficiently deoxidized and blow holes were formed in the weld metal. The weld metal had a low toughness due to insufficient B recovery and could not meet the required impact performance. :3ufficient TiN that suppresses ferrite band could not be precipitated due to the insufficient reduction of TiO~ and ferrii;e bands were formed in the weld metal.
The flux-cored wire in Comparative example 27 has a Ti02 content smaller than 4.2~ by mass, which is the lower limit Ti02 content specified by the present invention, and a fluorine compound content in terms of F content greater than 0.55% by mass, which is the upper limit fluorine compound content in terms of F content specified by the present invention. Arcs were unstable during welding, the bead covering performance of slag was unsatisfactory, and unacceptable convex beads were formed by vertical-position welding. Sufficient TiN that suppresses ferrite band could not be precipitated due to the insufficient reduction of the small Ti02 content and ferrite bands were formed in the weld metal.
The flux-cored wire in Comparative example 28 has an Al content and N content greater than 0.50 by mass and O.OS5o by mass, respectively, which are the upper limit A1 content and the upper limit N content specified by the present invention.
The removability of slag was unsatisfactory and blow holes were formed in the weld metal. The weld metal hardened due to the excessive A1 content and, consequently, the tensile strength was excessively high. The amount of solid solution of N was large due to the excessive N content and, con.sequer~tly, the weld metal had a low tcughness and could not meet the required impact performance.
The flux-cored wire in Comparative example 29 has a B
content and N content greater than 0.020~s by mass and O.OiSo by mass, respectively, which are the upper limit B content and the upper limit N content specified by the present invention.
The removability of slag was unsatisfactory and blow holes were _5~_ formed in the weld metal. The amount of solid solution of N
was large due to the excessive N content, the weld metal had a low toughness and could not meet the required impact performance.
The flux-cored wires in Examples 1 to 35 have C, Si, Mn, Cr, Mo, Mg, N and B contents in the ranges specified by the present invention, the fluxes of those flux-cored wires contain TiO~ and the fluorine compound, t:he Ti.02 contents and the fluoride compound contents in terms of F content of those flux-cored wires are in the ranges specified by the present invention, and the A1 contents, the Nb cantents and the V
contents of those flux cared wires are not greater than the upper limits of A1 content, Nb content and V content. All the weld metals produced by welding using the flux-cored wires in Examples 1 to 35 were satisfactory in radiant-ray transmitting performance, were excellent in tensile strength and toughness after PWHT, any ferrite bands were not formed at all in those weld metals even after the weld metals had been processed at high temperatures for a long time for PWHT . All the weld metals formed by welding using the f? ux-cored wires in Examples were acceptabl a . The flux-cored wires in Examples 1 to 10, Examples 12 to 25 and Examples 29 to 35 contain Ti and/or Zr, the Ti contents and/or the Zr contents of those rwlux-cared wires are in the content ranges specified by the presE:nt invention. Thus, the weld metals produced by welding using those flux-cored _~6_ wires of the present invention were excellent in toughness, compared with the other Examples. All the flux-cored wires in Examples 1 to 35 excluding the flux-cored wire in Example have Mn contents not greater than 1.450 by mass, which is the upper limit Mn content specified by th.e present invention, and those flux-cored wires formed beads of very satisfactory shapes by vertical -position welding.
Iri the flux-cored wires in Examples 1 to 6 and Examples 6, 8, 9, 19, 20, 34 and 35, the ratio of total Ti content to N content are in the range of 250 to 500, and the weld metals produced by welding using those f~_ux-cored wires were superior in toughness to the weld metals produced by welding using the flux-cared wires in other examples as shown in Fig. 2, which is a graph showing the dependence of the Ch.arpy impact energies 2""""E_18°~ (Avg. ? of weld metals on the ratio of total Ti content to N content.
As apparent form the foregoing dev;cription, according to the present invention, the formation of ferrite bands in the weld metals is suppressed even if t:he weld metals are processed at high temperatures for a long time for PWHT, the reduction of tensile strength is prevented, and the weld metals are excellent in toughness. The flux-cored wires of the present invention for the gas-shielded arc welding of work-pieces of heat-resisting low alloy steels are satisfactory in usability not only in flat welding but also in Vertical welding 7_ and overhead welding.
Although the invention has been dErscribed in its preferred embodiments with a certain degree of particularity, obviously many changes and variations azve possible therein.
It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit thereof.
_~g_

Claims (4)

1. A flux-cored wire for gas-shielded arc welding comprising:

a steel sheath, and a flux filled in the steel sheath;

wherein the flux-cored wire has, on the basis of the total mass of the flux-cored wire, a C content of 0.20% by mass or below, a Si content in the range of 0.06 to 1.10% by mass, a Mn content in the range of 0.55 to 1.60% by mass, a Cr content of 2.60% by mass or below, a Mo content in the range of 0.30 to 1.50% by mass, a Mg content in the range of 0.20 to 1.50%
by mass, a N content in the range of 0.005 to 0.035% by mass and a B content in the range of 0.001 to 0.020% by mass the flux has, on the basis of the total mass of the flux-cored wire, a TiO2 content in the range of 4.2 to 8.2%
by mass and a fluorine compound content in terms of F content in the range of 0.025 to 0.55% by mass, and the flux-cored wire has, on the basis of the total mass of the flux-cored wire, an Al content of 0.50% by mass or below, a Nb content of 0.015% by mass or below, and a V content of 0.015% by mass or below.

2. The flux-cored wire for gas-shielded arc welding according to claim 1, wherein the Mn content is in the range of 0.55 to 1.45% by mass on the basis of the total mass of the flux-cored wire.

3. The flux-cored wire for gas-shielded arc welding according to claim 1 further containing, on the basis of the total mass of the flux-cored wire at least one selected from the group consisting of Ti other than TiO2 in a Ti content in the range of 0.005 to 0.3% by mass and Zr in a Zr content in the range of 0.002 to 0.3% by mass.

4. The flux-cored wire according to claim 1, wherein the ratio of total Ti content to N content is in the range of 250 to 500, the total Ti content and they N content being the Ti content and the N content on the basis of the total mass of the flux-cored wire.