CA1070772A - Submerged arc welding process including a plurality of superimposed weld metal layers - Google Patents
Submerged arc welding process including a plurality of superimposed weld metal layersInfo
- Publication number
- CA1070772A CA1070772A CA274,799A CA274799A CA1070772A CA 1070772 A CA1070772 A CA 1070772A CA 274799 A CA274799 A CA 274799A CA 1070772 A CA1070772 A CA 1070772A
- Authority
- CA
- Canada
- Prior art keywords
- percent
- submerged arc
- welding process
- weld metal
- arc welding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K33/00—Specially-profiled edge portions of workpieces for making soldering or welding connections; Filling the seams formed thereby
- B23K33/004—Filling of continuous seams
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3601—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
- B23K35/3602—Carbonates, basic oxides or hydroxides
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Nonmetallic Welding Materials (AREA)
- Arc Welding In General (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Submerged arc welding process for 3.5% Ni steel which can provide a welded portion having a satisfactory impact resis-tance at low temperatures such as below minus 100°C. In the process, use is made of a flux having a basicity as defined by a formula in weight percentages of between 1.5 and 3.
The weld metal is deposited in a plurality of superimposed welded layers, each having a thickness less than 7 mm so that the weld metal in an underlying layer is thermally affected by an adjacent overlying layer whereby recrystallization is effected in sub-stantial thickness of the underlying layer to provide a fine crys-talline structure.
Submerged arc welding process for 3.5% Ni steel which can provide a welded portion having a satisfactory impact resis-tance at low temperatures such as below minus 100°C. In the process, use is made of a flux having a basicity as defined by a formula in weight percentages of between 1.5 and 3.
The weld metal is deposited in a plurality of superimposed welded layers, each having a thickness less than 7 mm so that the weld metal in an underlying layer is thermally affected by an adjacent overlying layer whereby recrystallization is effected in sub-stantial thickness of the underlying layer to provide a fine crys-talline structure.
Description
~C~7~77~Z
The present invention relates to a submerged arc weld~
ing process and more particularly, to a submerged arc welding process suitable for structural members which are subjected in use to low temperatures. More particularly, the present inven-tion relates to a submerged welding process in which weld metal is deposited in a plurality of superimposed layers.
Conventionally, vessels for s~oring liquefied gas such as liquefied nitrogen, li~uefied oxygen or the like, are con-structed from s-teel material by means of hand welding. Since these vessels are subjected in use to extreme low temperatures such as below minus 100C, it is very important to provide an adequate impact-resistant property at such low temperatures.
From the view point of manufacture it is desi.rable to automatically perform the welding operation using for example a submerged arc welding process, however, conventional submerged arc weld.ing processes have not been satisfactory for structures which are subjected in use to low temperatures particularly in respect of the toughness of the weld metal. Such conventional submerged arc welding processes are conducted with a relatively low thermal input which is expected as being effective to pro-duce fine crystalline structure having a satisEactory impactresistance. However, it has not been possible to provide an ade~uate impact resistance at low temperatures only through a relatively low thermal input.
The present invention has therefore an object to pro-vide a submerged arc welding process which can produce a weld metal having a high impact resistance property at extremely low temperatures.
Another object o-f the present invention is to provide a submerged arc weLding process which is particularly suitable for use in constructing vessels serviced at extremely low temp-eratures.
A further object o-E the present invention is to provide a submerged arc welding process in which weld meta:L is deposited ~L~'7~772 in plurality of superimposed layers so that the metal in one deposited layer receives thermal effect from the overlaid layer to produce recrystallized fine structures.
~ ccording to the present invention, the above and other objects can be accomplished by a submerged arc welding process in which use is made of flux having a basicity as defined by a formula CaiO M~O in weight percentage of between 1.5 and 3 and which cornprises the step of producing a plurality of deposited layers of weld metal under a welding current of 400 to 700A and an arc voltage of 35 to 48V, each of said layers having a thick-ness not greater than 7 mm so that the weld metal in an under-lying layer is thermally affected by an adjacent overlying layer whereby recrystallization is effected iIl substantial thickness of the underlying layer.
Accordiny to the present invention, it is preferred to use a bond type flux including on the basis of weight 10 to 30 percent of SiO2, 8 to 20 percent of A12O3, 25 to 45 percent of MgO, 10 to 30 percent of CaO, 7 to 20 percent of CaF2 and at least one selected from metallic Si, Fe-Si and Fe-5i-Mn in an amount of 0 to 0.6 percent calculated in term of metallic Si.
Where the welding process is applied to a steel material contain-ing a relatively high percentages, for example 3~5% nickel, it is also preferred to use a welding electrode containing on the basis of weight 5 to 25 percent of CaF2, 2.5 to 5.5 percent of Ni, 0 to 0.5 percent of Mo, 0 to 0.5 percent of Ti and the bal-ance substantially of Fe. ~-Where the weld metal layers are deposited in staggered ~ , relationship, the transverse distance between the highest por-tion of an underlying layer and that of an adjacent overlying layer should not be greater than 5 mm. Further, it is also recommend-able to maintain the thermal input ~0,000 J/cm.
The present invention is based on the findings that, in
The present invention relates to a submerged arc weld~
ing process and more particularly, to a submerged arc welding process suitable for structural members which are subjected in use to low temperatures. More particularly, the present inven-tion relates to a submerged welding process in which weld metal is deposited in a plurality of superimposed layers.
Conventionally, vessels for s~oring liquefied gas such as liquefied nitrogen, li~uefied oxygen or the like, are con-structed from s-teel material by means of hand welding. Since these vessels are subjected in use to extreme low temperatures such as below minus 100C, it is very important to provide an adequate impact-resistant property at such low temperatures.
From the view point of manufacture it is desi.rable to automatically perform the welding operation using for example a submerged arc welding process, however, conventional submerged arc weld.ing processes have not been satisfactory for structures which are subjected in use to low temperatures particularly in respect of the toughness of the weld metal. Such conventional submerged arc welding processes are conducted with a relatively low thermal input which is expected as being effective to pro-duce fine crystalline structure having a satisEactory impactresistance. However, it has not been possible to provide an ade~uate impact resistance at low temperatures only through a relatively low thermal input.
The present invention has therefore an object to pro-vide a submerged arc welding process which can produce a weld metal having a high impact resistance property at extremely low temperatures.
Another object o-f the present invention is to provide a submerged arc weLding process which is particularly suitable for use in constructing vessels serviced at extremely low temp-eratures.
A further object o-E the present invention is to provide a submerged arc welding process in which weld meta:L is deposited ~L~'7~772 in plurality of superimposed layers so that the metal in one deposited layer receives thermal effect from the overlaid layer to produce recrystallized fine structures.
~ ccording to the present invention, the above and other objects can be accomplished by a submerged arc welding process in which use is made of flux having a basicity as defined by a formula CaiO M~O in weight percentage of between 1.5 and 3 and which cornprises the step of producing a plurality of deposited layers of weld metal under a welding current of 400 to 700A and an arc voltage of 35 to 48V, each of said layers having a thick-ness not greater than 7 mm so that the weld metal in an under-lying layer is thermally affected by an adjacent overlying layer whereby recrystallization is effected iIl substantial thickness of the underlying layer.
Accordiny to the present invention, it is preferred to use a bond type flux including on the basis of weight 10 to 30 percent of SiO2, 8 to 20 percent of A12O3, 25 to 45 percent of MgO, 10 to 30 percent of CaO, 7 to 20 percent of CaF2 and at least one selected from metallic Si, Fe-Si and Fe-5i-Mn in an amount of 0 to 0.6 percent calculated in term of metallic Si.
Where the welding process is applied to a steel material contain-ing a relatively high percentages, for example 3~5% nickel, it is also preferred to use a welding electrode containing on the basis of weight 5 to 25 percent of CaF2, 2.5 to 5.5 percent of Ni, 0 to 0.5 percent of Mo, 0 to 0.5 percent of Ti and the bal-ance substantially of Fe. ~-Where the weld metal layers are deposited in staggered ~ , relationship, the transverse distance between the highest por-tion of an underlying layer and that of an adjacent overlying layer should not be greater than 5 mm. Further, it is also recommend-able to maintain the thermal input ~0,000 J/cm.
The present invention is based on the findings that, in
-2-7~
a welding structure having a plurality of superlmposed layers of weld metal, an underlying layer receives a thermal influence ~rom an adjacent overlying layer when the latter is being deposited so that the former is caused to produce a recrystallizecl fine structure and that the fine structure can ef:Eectively be utilized in obtaining an improved impact resistance at low temperatures such as below minus 100C. Thus, the present invention is char-acterized b~ the fact that the weld metal is deposited in rela-tiveLy thin superimposed layers whereby only a relatively thin portion in each layer remains thermally unaffected. According to the present invention, such thermally unaffected portion in each layer is less than 2 mm so that substantial part of the layer is accounted for by the recrystallized metal of high impact resistance.
In order to obtain a high impact resis-tarlce and an irn-proved toughness, it is required to maintain the oxygen content in the weld metal below 300 ppm., and this is accomplished through a use of flux having the basicity greater than 1.5. Fur-ther, a higher basicity is effective to decrease the Si content in the weld metal. ~owever, since an increase in the basicity has an adverse effect on the weldability, the value should not exceed 3Ø
With respect to the flux, the aforementioned composi-tion is recommendable for welding steel material containing high percentages of nickel for the following reasons.
The SiO2 has an influence on the melting point of the flux and where the SiO2 content is less than 10 percent there will be an increase in the melting point of the flux so that ad-verse efEects will be seen in the performance oE the welding operation and also in the appearance of the welded beads. With the SiO2 content exceedlng 30 percent, the SiO2 will be chemic-ally reduced and there will be an increase in the Si content in 1~7~77'h the weld metal resulting in a poor toughness of the weld metal.
Th A12O3 ha,s an influence on the appearance of the welded beads and an acceptable range is between ~ and 20 percent.
With the MgO content less than 25 percent, it will be difficult to maintain the basicity at a desirable level but where the con-tent ls greater than 45 percent the melting point of the flux will be increased to an unacceptable level. The CaO content should be greater than 10 percent in order to maintain the basic- ;
ity within the desired range but it will have an adverse effect on the workability if it is increased beyond 30 percent.
The CaF2 content should be greater than 7 percent in order to provide a satisfactory appearance on the welded beads.
Mowever, excessive addition of CaF2 causes an unstable welding arc so that the content should be lower than 20 percent. In order to maintain the silicon content in the weld metal below 0.20 percent, it is required to maintain the silicon content of metallic Si, E'e-Si and Fe-Si-Mn in the flux to lower than 0.6 percent. Otherwise, there will be an adverse effect on the toughness at low temperatures due to an increase in the silicon content in the weld metalO As mentioned above, silicon contain-ing deoxidizing agent may be metallic Si, Fe-Si, Fe-Mn-Si. It ~ :~
is of course possible to use a materia1 other than silicon as .
the deoxidizing agent. For example, manganese may be used ~or .:
the purpose. Thus, the flux of the present invention may contain deoxidizing agent in an amount of 0.6% or less calculated in terms of silicon. It is mentioned, the Si content in Fe-Si and Fe-Si-Mn is not constant. For example, Fe-Si contains 20 to 70 percent of Si. Therefore, it is difficult to limit the amount of Fe-Si per se, ~ecause the amount of Si contained in Fe-Si is important to the flux.
Regarding the cored wire, it ha.s been found that the CaF2 content should be greater than 5 percent to the total weight ~, ~,, 977~
of the wire. Otherwise, blow-holes are apt to be produced in the weld metal and there wil]. be a decrease in the toughness. With the CaF2 content greater than 5 percent, there is a remarkable decrease in~the oxygen content in the molten metal so that blow--4a-~7~)77Z
holes are prevented and the toughness is improved. However, the CaF2 content should not exceed 25 percent because an excessive CaF2 content makes the welding arc unstable and causes a poor workability.
In order to ensure an adequate impact-resistant prop-erty at minus 100C, it is necessary to maintain the nickel con-tent in the core wire in an amount of higher than 2.5 percent, however, where the content increases beyond 5.5 percent, it may cause cracks under high temperature.
10 Molybdenum may be incorporated into the cored wire for obtaining an increased strength of the weld metal but the content shall not exceed 0.5 percent because it may have an ~dverse ef-fect on the impact-resistant property at low temperatures where the Mo content is above this value.
Titanium may be also incorporated into the cored wire because it is effective to produce fine crystalline structures which serve to provide an improved impact-resistant property . .
under low temperature. However, the titanium may be omitted because even when no titanium is contained it is possible to . ~ .
obtain a satisfactory impact-resistant property around minus 100C.
Where the Ti content is greater than 0.5 percent, there will be a decrease in the toughness due to an increase in the silicon content in the weld metal.
Nickel, molybdenum and titanium in the core material may be incorporated into the welding electrode in the form of ferrous alloy thereof, for example, Fe-Ni, Fe-Mo, and Fe-Ti.
Fe-Ni, Fe-Mo or Fe-Ti may be incorporated into the electrode in the above mentioned amount calculated in term of nickel, molyb-denum or titanium. It is of course possible that nickel, moly-bdenum or titanium may be added to the electrode in the form ofelementary metal.
According to the present invention, the process is performed with a welding current of 400 to 700A, an arc voltage of rd ~ ~
1~7~77;~
35 to ~V and a thermal input less than 40,000 J/cm. With -the welding current less than 400A, it becomes difficult to maintain a stable welding arc, while the welding curren-t exceeding 700A
produces deposited layers having a thickness greater than the desirable value. With the arc voltage less tharl 35V, there will be an increase in the melting rate of the weld me-tal while the voltage greater than 48V causes unstable welding arc. The limit of the thermal input is necessary in order to maintain the fine crystalline structures and the thin deposited layers of the weld-ing metal.
The inventors also had found that under the aforemen-tioned welding condition of the present invention, welding should be preferably conducted at a velocity of 20 to 50 cm/minute to provide deposit layer of a thickness less than 7 mm.
The features of the present invention will become more apparent from the following descriptions which proceed making reference to the accompanying drawings, in which:
Figure 1 is a fragmentary perspective view showing steel plates which are being welded in accordance with the pre-sent invention, Figure 2 is an enlarged fragmentary sectional viewshowing an example of deposited layers of weld metal, Figures 3A, B and C show examples of deposited layers or beads of the weld metal, and Figure 4 is a sectional view showing an example of a welding groove formed in the material to be welded.
Referring to Figure 1, a pair of plates 1 and 2 Of nickel containing steel such as 3.5% nickel steel are placed at end-to-end relationship wi-th a substantially U-shaped groove 3 formed at the abutting portion. A su~merged arc welding is per-formed under the aforementioned welding conditions using the aforementioned flux and the aforementioned welding metal -to form ~,c~ -6-a plurality of deposited layers 4 which are posi-tioned in super-imposed staygered relationship. According to the present inven- , tion, the thic~ness T of each deposited layer 4 is less than 7 mm and in the illustrated staggered arrangement the offset or traverse distance S between two succeeding layers is less than 5 mm. The term `'traverse distance`' herein used means a distance between the centers or highest portions of two superimposed layers as measured in the direction perpendicular to the thickwise direction of the layer and perpendicular to the welding line shown by a phantom line C.
Referring specifically to the layer 4a shown in Figure 1, it receives a thermal effect at the area designated by the numeral 5 when the adjacent layer 4b is formed so that recrys-tallization proceeds in the area 5 to produce a fine crystalline structure. Further, when another adjacent layer 4c is deposited, the metal in the layer 4a receives a thermal effect at the area designated by the numeral 6 so that a fine crystalline structure is produced in the area 6. Since the layer 4 is relatively thin, the layer is substantially occupied by the recrystallized fine structure and the thermally unaffected layer is 2 mm thick or less.
Thus, it is possible to produce a weld structure havlng a high impact resistance at extremeLy low temperatures. Fiyure 2 shows the deposited layers 4 of the weld metal in detai.l. In the draw-ing, the numeral 7 shows the area where the metal has received a thermal effect and recrystallization has proceeded.
Referring now to Figure 3, there are shown several ex-amples of deposited'layer arrangements. More specifically, Fig-ure 3A shows an example wherein layers 4 of the weld metal are deposited one on another without any transverse offset, while Figure 3B shows an example of staggered arrangement. It will be noted that the latter arrangement is more preferable in respect of recrystallization. In Figure 3C, it will be no-ted that a transverse distance S bet.ween the highest ,~
portion of a layer and that of a succeediny superimposed layer has also an influence on -the area of thermally unaffected portion 8. Thus, the inventors propose to maintain the distance below S mm.
Examples:
Welding operations were performe~d on 3.5% Ni steel meeting the specification of ASTM A-203 and having the dimension as shown in Figure 4. In performing the welding processes, flux materials have been prepared as shown in Table I.
TABLE I
CaOMgO SiO2 A123 CaF2 Basicity _ A 20 29 38 10 3 1.3 B 20 25 25 20 10 1.8 C 16 26 21 20 17 2.0 D 16 37 21 14 12 2.5 Mote: The basicity is defined by the formula B = iO ~ (in weight %) Further, the welding electrode contained on the basis of weight 10 percent of CaF2, 2.7 percent of Ni, 0.5 percent of Mo and the balance of Fe a mild steel. The mild steel had a composition of by weight, 0.05 percent of carbon, 0.50 percent of manganese and the balance of iron. The weldlng operations were performed as shown in the Table II and the welded speci-mens were formed with U-shaped notches of 2 mm width at the welded portions and subjected to Charpy impact tests at a temp-erature of minus 101C. The results are also shown in Table II, ~L~37~77'~
u~ ~ n 0 cn r~) N~n ~ 0 d~ ~n~ ~ ~ o ,~ c~ ~1 0 a~ o ,~
H~
r~ ., o Ln o o o o o o o Ln o n o a) a) ~ ~ ~ ~n ~ ~n o~ ~ Ln Ln 1- ~ ~ ~
~ ~ 3 P ~ NNN~ NNNNNNNN ...
X C~ , ~'~
r~$ ~ :
~ o ~ ~ n 1~N 1-- 0 0 ~ Ln ~ r~ 0 ~ -. ~ ~
I;jL N('~)N N ~-1 O O ~ r l ~1 0 0 : .
~1 ~~ 1 o o ~ n 'n ~ ~ r ~ n o 0 ~ o~ ~n r~ d' d~ Ln n ~9 ~ ~
~a) a) ..
~ ~ n 0 NN n ~n 1~ ~n N ~n ~ N
~-rj N~Or;~ Nr;r;r;~ d~ O ,;
E~ ~ ~ .
H
~ ~0 r~ OOOOO OOOOOOOO ~ ' m~ .~ ~ ~ ~ o g o o o 8 o g o o o E~ ,~ a~ P~ n o n Ln Ln Ln o o n n 1~ n n r ~H- N~N N~
V
,~ rd^ oO O n nN COON n Ln n O N ~ d~ dl d~ ~ d~ d~ d~ d~ d~ r~l d~
a welding structure having a plurality of superlmposed layers of weld metal, an underlying layer receives a thermal influence ~rom an adjacent overlying layer when the latter is being deposited so that the former is caused to produce a recrystallizecl fine structure and that the fine structure can ef:Eectively be utilized in obtaining an improved impact resistance at low temperatures such as below minus 100C. Thus, the present invention is char-acterized b~ the fact that the weld metal is deposited in rela-tiveLy thin superimposed layers whereby only a relatively thin portion in each layer remains thermally unaffected. According to the present invention, such thermally unaffected portion in each layer is less than 2 mm so that substantial part of the layer is accounted for by the recrystallized metal of high impact resistance.
In order to obtain a high impact resis-tarlce and an irn-proved toughness, it is required to maintain the oxygen content in the weld metal below 300 ppm., and this is accomplished through a use of flux having the basicity greater than 1.5. Fur-ther, a higher basicity is effective to decrease the Si content in the weld metal. ~owever, since an increase in the basicity has an adverse effect on the weldability, the value should not exceed 3Ø
With respect to the flux, the aforementioned composi-tion is recommendable for welding steel material containing high percentages of nickel for the following reasons.
The SiO2 has an influence on the melting point of the flux and where the SiO2 content is less than 10 percent there will be an increase in the melting point of the flux so that ad-verse efEects will be seen in the performance oE the welding operation and also in the appearance of the welded beads. With the SiO2 content exceedlng 30 percent, the SiO2 will be chemic-ally reduced and there will be an increase in the Si content in 1~7~77'h the weld metal resulting in a poor toughness of the weld metal.
Th A12O3 ha,s an influence on the appearance of the welded beads and an acceptable range is between ~ and 20 percent.
With the MgO content less than 25 percent, it will be difficult to maintain the basicity at a desirable level but where the con-tent ls greater than 45 percent the melting point of the flux will be increased to an unacceptable level. The CaO content should be greater than 10 percent in order to maintain the basic- ;
ity within the desired range but it will have an adverse effect on the workability if it is increased beyond 30 percent.
The CaF2 content should be greater than 7 percent in order to provide a satisfactory appearance on the welded beads.
Mowever, excessive addition of CaF2 causes an unstable welding arc so that the content should be lower than 20 percent. In order to maintain the silicon content in the weld metal below 0.20 percent, it is required to maintain the silicon content of metallic Si, E'e-Si and Fe-Si-Mn in the flux to lower than 0.6 percent. Otherwise, there will be an adverse effect on the toughness at low temperatures due to an increase in the silicon content in the weld metalO As mentioned above, silicon contain-ing deoxidizing agent may be metallic Si, Fe-Si, Fe-Mn-Si. It ~ :~
is of course possible to use a materia1 other than silicon as .
the deoxidizing agent. For example, manganese may be used ~or .:
the purpose. Thus, the flux of the present invention may contain deoxidizing agent in an amount of 0.6% or less calculated in terms of silicon. It is mentioned, the Si content in Fe-Si and Fe-Si-Mn is not constant. For example, Fe-Si contains 20 to 70 percent of Si. Therefore, it is difficult to limit the amount of Fe-Si per se, ~ecause the amount of Si contained in Fe-Si is important to the flux.
Regarding the cored wire, it ha.s been found that the CaF2 content should be greater than 5 percent to the total weight ~, ~,, 977~
of the wire. Otherwise, blow-holes are apt to be produced in the weld metal and there wil]. be a decrease in the toughness. With the CaF2 content greater than 5 percent, there is a remarkable decrease in~the oxygen content in the molten metal so that blow--4a-~7~)77Z
holes are prevented and the toughness is improved. However, the CaF2 content should not exceed 25 percent because an excessive CaF2 content makes the welding arc unstable and causes a poor workability.
In order to ensure an adequate impact-resistant prop-erty at minus 100C, it is necessary to maintain the nickel con-tent in the core wire in an amount of higher than 2.5 percent, however, where the content increases beyond 5.5 percent, it may cause cracks under high temperature.
10 Molybdenum may be incorporated into the cored wire for obtaining an increased strength of the weld metal but the content shall not exceed 0.5 percent because it may have an ~dverse ef-fect on the impact-resistant property at low temperatures where the Mo content is above this value.
Titanium may be also incorporated into the cored wire because it is effective to produce fine crystalline structures which serve to provide an improved impact-resistant property . .
under low temperature. However, the titanium may be omitted because even when no titanium is contained it is possible to . ~ .
obtain a satisfactory impact-resistant property around minus 100C.
Where the Ti content is greater than 0.5 percent, there will be a decrease in the toughness due to an increase in the silicon content in the weld metal.
Nickel, molybdenum and titanium in the core material may be incorporated into the welding electrode in the form of ferrous alloy thereof, for example, Fe-Ni, Fe-Mo, and Fe-Ti.
Fe-Ni, Fe-Mo or Fe-Ti may be incorporated into the electrode in the above mentioned amount calculated in term of nickel, molyb-denum or titanium. It is of course possible that nickel, moly-bdenum or titanium may be added to the electrode in the form ofelementary metal.
According to the present invention, the process is performed with a welding current of 400 to 700A, an arc voltage of rd ~ ~
1~7~77;~
35 to ~V and a thermal input less than 40,000 J/cm. With -the welding current less than 400A, it becomes difficult to maintain a stable welding arc, while the welding curren-t exceeding 700A
produces deposited layers having a thickness greater than the desirable value. With the arc voltage less tharl 35V, there will be an increase in the melting rate of the weld me-tal while the voltage greater than 48V causes unstable welding arc. The limit of the thermal input is necessary in order to maintain the fine crystalline structures and the thin deposited layers of the weld-ing metal.
The inventors also had found that under the aforemen-tioned welding condition of the present invention, welding should be preferably conducted at a velocity of 20 to 50 cm/minute to provide deposit layer of a thickness less than 7 mm.
The features of the present invention will become more apparent from the following descriptions which proceed making reference to the accompanying drawings, in which:
Figure 1 is a fragmentary perspective view showing steel plates which are being welded in accordance with the pre-sent invention, Figure 2 is an enlarged fragmentary sectional viewshowing an example of deposited layers of weld metal, Figures 3A, B and C show examples of deposited layers or beads of the weld metal, and Figure 4 is a sectional view showing an example of a welding groove formed in the material to be welded.
Referring to Figure 1, a pair of plates 1 and 2 Of nickel containing steel such as 3.5% nickel steel are placed at end-to-end relationship wi-th a substantially U-shaped groove 3 formed at the abutting portion. A su~merged arc welding is per-formed under the aforementioned welding conditions using the aforementioned flux and the aforementioned welding metal -to form ~,c~ -6-a plurality of deposited layers 4 which are posi-tioned in super-imposed staygered relationship. According to the present inven- , tion, the thic~ness T of each deposited layer 4 is less than 7 mm and in the illustrated staggered arrangement the offset or traverse distance S between two succeeding layers is less than 5 mm. The term `'traverse distance`' herein used means a distance between the centers or highest portions of two superimposed layers as measured in the direction perpendicular to the thickwise direction of the layer and perpendicular to the welding line shown by a phantom line C.
Referring specifically to the layer 4a shown in Figure 1, it receives a thermal effect at the area designated by the numeral 5 when the adjacent layer 4b is formed so that recrys-tallization proceeds in the area 5 to produce a fine crystalline structure. Further, when another adjacent layer 4c is deposited, the metal in the layer 4a receives a thermal effect at the area designated by the numeral 6 so that a fine crystalline structure is produced in the area 6. Since the layer 4 is relatively thin, the layer is substantially occupied by the recrystallized fine structure and the thermally unaffected layer is 2 mm thick or less.
Thus, it is possible to produce a weld structure havlng a high impact resistance at extremeLy low temperatures. Fiyure 2 shows the deposited layers 4 of the weld metal in detai.l. In the draw-ing, the numeral 7 shows the area where the metal has received a thermal effect and recrystallization has proceeded.
Referring now to Figure 3, there are shown several ex-amples of deposited'layer arrangements. More specifically, Fig-ure 3A shows an example wherein layers 4 of the weld metal are deposited one on another without any transverse offset, while Figure 3B shows an example of staggered arrangement. It will be noted that the latter arrangement is more preferable in respect of recrystallization. In Figure 3C, it will be no-ted that a transverse distance S bet.ween the highest ,~
portion of a layer and that of a succeediny superimposed layer has also an influence on -the area of thermally unaffected portion 8. Thus, the inventors propose to maintain the distance below S mm.
Examples:
Welding operations were performe~d on 3.5% Ni steel meeting the specification of ASTM A-203 and having the dimension as shown in Figure 4. In performing the welding processes, flux materials have been prepared as shown in Table I.
TABLE I
CaOMgO SiO2 A123 CaF2 Basicity _ A 20 29 38 10 3 1.3 B 20 25 25 20 10 1.8 C 16 26 21 20 17 2.0 D 16 37 21 14 12 2.5 Mote: The basicity is defined by the formula B = iO ~ (in weight %) Further, the welding electrode contained on the basis of weight 10 percent of CaF2, 2.7 percent of Ni, 0.5 percent of Mo and the balance of Fe a mild steel. The mild steel had a composition of by weight, 0.05 percent of carbon, 0.50 percent of manganese and the balance of iron. The weldlng operations were performed as shown in the Table II and the welded speci-mens were formed with U-shaped notches of 2 mm width at the welded portions and subjected to Charpy impact tests at a temp-erature of minus 101C. The results are also shown in Table II, ~L~37~77'~
u~ ~ n 0 cn r~) N~n ~ 0 d~ ~n~ ~ ~ o ,~ c~ ~1 0 a~ o ,~
H~
r~ ., o Ln o o o o o o o Ln o n o a) a) ~ ~ ~ ~n ~ ~n o~ ~ Ln Ln 1- ~ ~ ~
~ ~ 3 P ~ NNN~ NNNNNNNN ...
X C~ , ~'~
r~$ ~ :
~ o ~ ~ n 1~N 1-- 0 0 ~ Ln ~ r~ 0 ~ -. ~ ~
I;jL N('~)N N ~-1 O O ~ r l ~1 0 0 : .
~1 ~~ 1 o o ~ n 'n ~ ~ r ~ n o 0 ~ o~ ~n r~ d' d~ Ln n ~9 ~ ~
~a) a) ..
~ ~ n 0 NN n ~n 1~ ~n N ~n ~ N
~-rj N~Or;~ Nr;r;r;~ d~ O ,;
E~ ~ ~ .
H
~ ~0 r~ OOOOO OOOOOOOO ~ ' m~ .~ ~ ~ ~ o g o o o 8 o g o o o E~ ,~ a~ P~ n o n Ln Ln Ln o o n n 1~ n n r ~H- N~N N~
V
,~ rd^ oO O n nN COON n Ln n O N ~ d~ dl d~ ~ d~ d~ d~ d~ d~ r~l d~
3 ~>
~_ ooooo oooooooo S~ ~ n o o o o NLnO Ln O n ~ Ln ~_ ~ ~ c~ ~o Ln ~ ~ Ln n ~D ~ d~ d~
~ ' ' ~ a a a a ~ a a o a a m a a .', '.
U~ r~N~-n ~ ~ 0 ~ o ,~
~ r-lr~r~r~
U~ ~ _ Comr~a ra tive Examples Invent ion _ _ . _ r~ O
. ~ _ g _ .~7~7Z
In the above tests, it was investigated -that the speci-mens 1 and 2 h~d relatively thic]c beads of cross-s~ction having relatively small radius of curvature at the surface of each layer.
This is caused by an insufficient arc voltage. Thus, there was a relatively large area of thermally unaffected metal. ~s the resu]ts, they showed very poor impact resistance. In the speci-men 2, it will be seen that the relatively large transverse distance S had an adverse effect on the impact resi~tance.
In the specimens 3 and 4, it will be seen that exces-sive welding current and thermal input have produced depositedlayers of excessive thickness. Therefore, it has not been pos-sible to produce an adequate coverage of recrystallized fine s-truc-tures. This tendency is particularly significant in the specimen ~ because, in this specimen, the welding metal has been deposited without transverse offset between two adjacent layers.
The specimen 5 was welded using the flux of lower basi-city. Therefore, there was an excessive amount of residual oxy-gen in the welded metal. The specimens 6 throug'n 13 which have been welded in accordance with the present invention had therm-ally unaffected areas of less than 2 mm thick. Thus, these speci-mens had a satisfactory impact resistance.
:'.'''
~_ ooooo oooooooo S~ ~ n o o o o NLnO Ln O n ~ Ln ~_ ~ ~ c~ ~o Ln ~ ~ Ln n ~D ~ d~ d~
~ ' ' ~ a a a a ~ a a o a a m a a .', '.
U~ r~N~-n ~ ~ 0 ~ o ,~
~ r-lr~r~r~
U~ ~ _ Comr~a ra tive Examples Invent ion _ _ . _ r~ O
. ~ _ g _ .~7~7Z
In the above tests, it was investigated -that the speci-mens 1 and 2 h~d relatively thic]c beads of cross-s~ction having relatively small radius of curvature at the surface of each layer.
This is caused by an insufficient arc voltage. Thus, there was a relatively large area of thermally unaffected metal. ~s the resu]ts, they showed very poor impact resistance. In the speci-men 2, it will be seen that the relatively large transverse distance S had an adverse effect on the impact resi~tance.
In the specimens 3 and 4, it will be seen that exces-sive welding current and thermal input have produced depositedlayers of excessive thickness. Therefore, it has not been pos-sible to produce an adequate coverage of recrystallized fine s-truc-tures. This tendency is particularly significant in the specimen ~ because, in this specimen, the welding metal has been deposited without transverse offset between two adjacent layers.
The specimen 5 was welded using the flux of lower basi-city. Therefore, there was an excessive amount of residual oxy-gen in the welded metal. The specimens 6 throug'n 13 which have been welded in accordance with the present invention had therm-ally unaffected areas of less than 2 mm thick. Thus, these speci-mens had a satisfactory impact resistance.
:'.'''
Claims (6)
1. A submerged arc welding process in which use is made of a flux having a basicity as defined by a formula in weight percentage of between 1.5 and 3 and which comprises step of producing a plurality of deposited layers of weld metal under a welding current of 400 to 700A and an arc voltage of 35 to 48V, each of said layers having a thickness not greater than 7 mm so that the weld metal in an underlying layer is thermally affected by an adjacent overlying layer whereby recrystalliza-tion is effected in substantial thickness of the underlying layer.
2. A submerged arc welding process in accordance with claim 1 in which said deposited layers of weld metal are arranged in staggered relationship, in a welding direction.
3. A submerged arc welding process in accordance with claim 2 in which said layers are arranged with a transverse distance between a highest portion of one layer and that of an adjacent superimposed layer is less than 5 mm.
4. A submerged arc welding process in accordance with claim 1 which is applied to weld nickel containing steel, said process using a bond-type flux containing on the basis of weight 10 to 30 percent of SiO2, 8 to 20 percent of A12O3, 25 to 45 percent of MgO, 10 to 30 percent of CaO, 7 to 20 percent of CaF2 and at least one selected from the group consisting of metallic Si, Fe-Si, Fe-Si-Mn in an amount 0.6 percent or less calculated in terms of metallic Si, whereby in the case of Fe-Si, Si contained in Fe-Si amounts for 0.6 weight percent or less of the flux.
5. A submerged arc welding process in accordance with claim 1, in which use is made of a welding electrode of cored wire consisting of a mild steel and core material, the core material including, on the basis of weight to the total weight of the welding electrode, 5 to 25 percent of CaF2, 2.5 to 5.5 percent of nickel, 0 to 0.5 percent of Mo, 0 to 0.5 percent of Ti.
6. A submerged arc welding process in accordance with claim 1 in which thermal input is maintained below 40,000 J/cm.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3396176A JPS52116752A (en) | 1976-03-26 | 1976-03-26 | Method of submerged arc welding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070772A true CA1070772A (en) | 1980-01-29 |
Family
ID=12401077
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA274,799A Expired CA1070772A (en) | 1976-03-26 | 1977-03-25 | Submerged arc welding process including a plurality of superimposed weld metal layers |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS52116752A (en) |
| CA (1) | CA1070772A (en) |
| DE (1) | DE2713285C3 (en) |
| FR (1) | FR2345260A1 (en) |
| GB (1) | GB1573246A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3421031A1 (en) * | 1984-06-06 | 1985-12-12 | M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 4200 Oberhausen | METHOD FOR PRODUCING A CONSTRUCTION PART BY SHAPING ORDER WELDING, AND CONSTRUCTION PART PRODUCED BY THE PROCESS |
| IT1261969B (en) * | 1992-11-05 | 1996-06-11 | BASIC ANIMATED WIRE NOT ALLOYED FOR ELECTRIC ARC WELDING UNDER GASEOUS PROTECTION, PARTICULARLY OF CARBON STEEL, EVEN FINE GRAIN | |
| JP4730749B2 (en) * | 2008-04-21 | 2011-07-20 | 東芝エレベータ株式会社 | Elevator cooling system |
-
1976
- 1976-03-26 JP JP3396176A patent/JPS52116752A/en active Granted
-
1977
- 1977-03-21 GB GB1177377A patent/GB1573246A/en not_active Expired
- 1977-03-25 DE DE19772713285 patent/DE2713285C3/en not_active Expired
- 1977-03-25 CA CA274,799A patent/CA1070772A/en not_active Expired
- 1977-03-25 FR FR7709047A patent/FR2345260A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2713285B2 (en) | 1979-05-17 |
| JPS5629623B2 (en) | 1981-07-09 |
| FR2345260B1 (en) | 1981-07-24 |
| DE2713285A1 (en) | 1977-10-06 |
| GB1573246A (en) | 1980-08-20 |
| DE2713285C3 (en) | 1980-01-31 |
| FR2345260A1 (en) | 1977-10-21 |
| JPS52116752A (en) | 1977-09-30 |
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