Implement best mode of the present invention
Below explain in detail the present invention.
Fig. 1 (a)-(d) is the diagram that schematically illustrates the notion of HAZ structure control.The HAZ structure of the Ti-oxide compound steel that Fig. 1 (a) expression is traditional, Fig. 1 (d) is illustrated in the HAZ structure in the steel of the present invention.In Fig. 1, reference number 1 is represented welding metal, and 2 represent welded heat affecting zone (HAZ), and 3 represent welded bonds.In the HAZ structure, 4 represent the γ crystal boundary, and GBF represents grain boundary ferrite crystal grain, and FSP represents ferrite side plate shape crystal grain, and IGF represents the ferrite crystal grain of intragranular phase transformation, and Bu represents upper bainite, and on behalf of martensite-austenite, MA form.
When the yield strength of Ti-oxide compound steel when present 420MPa increases to the 500MPa level, surpass 460PMa, and when adding alloying element and further increase to 550MPa,, therefore make it be difficult to guarantee enough CTOD performances near the HAZ hardening of welded bonds.HAZ structural representation in this state is shown among Fig. 1 (a).The fundamental cause that makes the HAZ hardening is the increase along with HAZ hardness, coarse grain-grain boundary ferrite (GBF) crystal grain and ferrite side-tabular (FSP) crystal grain of producing along the crystal boundary of thick γ crystal grain have increased the susceptibility of HAZ to brittle rupture, even ferrite (IGF) grain refining of the intragranular phase transformation that thick γ crystal grain inside is wherein formed.Therefore, must be by the susceptibility of refinement GBF crystal grain and FSP crystal grain reduction to brittle rupture.Hardened second reason is that the alloying element amount that adds in order to improve intensity increases the hardened processibility that has improved HAZ, and produces the microcosmic fragility phase that is called MA (martensite-austenite composition) in a large number, and this has quickened the generation of brittle rupture.Simultaneously, in the time will obtaining to be not less than the yield strength of 460MPa, must on the maximum possible degree, reduce MA.From foregoing as can be known, in order to obtain the CTOD performance of gratifying welding region under high-yield strength, removing above-mentioned two fragility reasons and keeping the metallographic effect (IGF) of Ti-oxide compound steel is a guilding principle.In other words, main points of the present invention are control HAZ structures, so that satisfy following 3 points simultaneously:
(1) refinement is along the GBF crystal grain and the FSP crystal grain that produce at the crystal boundary near the γ crystal grain among the HAZ of welded bonds.
(2) by producing the γ crystal grain inside of IGF grain refining in the close HAZ of welded bonds therein.
(3) be reduced in amount near the MA that produces among the HAZ of welded bonds.
At first, will explain a kind of means that obtain (1).For thick GBF crystal grain of refinement and FSP crystal grain, these two kinds of coarse grains are the reasons that produce brittle rupture, must make γ crystal grain littler.For the γ grain growth of strongly inhibited in the HAZ district of the welded bonds of close 1400 ℃ of heating, various steel compositions have been carried out extensive studies.The result, invented a kind of technology, wherein, by suitable control Mg and Al, the oxide particle of being made up of Mg and A1 of a large amount of ultra-fine 0.01-0.1 microns is dispersed in the steel, and the TiN particle of 0.01-0.5 micron is to precipitate with the oxide particle compound form that is used as nucleus.With the sedimentary TiN particle of complex form is heat-staple, even also do not grow up or dissolve near welded bonds, so their strong pinning γ crystal boundaries hinder it and move.Promptly use a large amount of welding heat inputs to weld, also can remain on 100 micron number magnitudes near near the γ grain-size the welded bonds.In some cases, the direct phase transformation nucleus as GBF crystal grain and FSP crystal grain of pinning particle itself that these exist at the γ crystal boundary is so the increase of phase transformation position also is the reason of GBF crystal grain and FSP grain refining.Be not less than 10,000/square millimeter and exist GBF crystal grain and FSP grain refining to certain size with the sedimentary this TiN particulate of complex form, this size can not produce detrimentally affect to the CTOP performance.If less than 10,000/square centimeter, it is not enough that the phase transformation nucleus quantity on the refinement of γ crystal grain and the γ crystal boundary becomes with the sedimentary TiN particle of complex form, therefore, therefore GBF crystal grain and the fully refinement of FSP crystal grain have reduced the CTOD performance.In some cases, sulfide is deposited on the TiN particle with complex form, but this can very influence its above-mentioned effect as pinning particle or phase transformation nucleus.
Fig. 1 (b) is a synoptic diagram of representing only it to be used the HAZ structure of above-mentioned (1) technology.Though GBF crystal grain and FSP crystal grain are by refinement, the inner involved triable structure that is called the MA of upper bainite of γ crystal grain covers, and only can not obtain enough CTOD with this technology.So, must be used in combination (2) the technology of hereinafter explaining.
To explain (2) the measure that obtains below.According to the present invention,, have a mind to add Mg for the above-mentioned superfine oxide particle of a large amount of generations.Owing to also contain Mg, in process of the present invention, utilize this Mg oxide particle that contains more greatly to study and produce IGF crystal grain with the oxide particle form of common size (several microns).As a result, find that following three conditions are important for IGF phase transformation nucleus.
1. there is minimum particle at least.
2. particle has suitable size.
3. particle contains Mn.
From condition 1., must there be the IGF phase transformation nucleus that is not less than 10/square millimeter at least with stable manner near in the HAZ of welded bonds.If IGF phase transformation nucleus is less than 10/square millimeter, it is unstable that the refinement of HAZ structure becomes.
From condition 2., in order to be effective as IGF phase transformation nucleus, particle must have and is not less than 0.5 micron size.If particle size is less than 0.5 micron, its ability as IGF phase transformation nucleus obviously reduces.In order to satisfy this condition, in process of the present invention, studied and used the oxide particle that is not less than 0.5 micron as IGF phase transformation nucleus.Yet, be undesirable greater than 10 microns oxide particles, because the source that they begin as brittle rupture.
About condition aspect 3., find that particle need contain the Mn that is not less than 0.3 quality % in order to be effective as IGF phase transformation nucleus.For this reason, hope is to introduce Mn in the oxide particle of 0.5-10 micron.In order to produce the pinning particle of super-refinement, Mg, Al and Ti are essential for the present invention, they by explain in (1) (Mg, Al) nitride of oxide compound and Ti is formed.Because these elements have the deoxidizing capacity stronger than Mn, therefore, the oxide particle of 0.5-10 micron mainly is made up of Mg, Al and Ti.So the Mn that stable introducing is not less than 0.3 quality % in the oxide particle of 0.5-10 micron is difficult.Because this point in process of the present invention, has been considered to contain Mn sulfide and has been deposited on the oxide particle with complex form.By using measure similarly, the Mn content in the composite particles can stably increase to 0.3 quality % or higher, and these particles can be effective as IGF phase transformation nucleus.To contain Mn sulfide in order seeking on oxide particle with the complex form precipitation, to study, therefore, the verified Mg content in oxide particle is important.Containing under the oxide particle situation that is not less than 10 quality %Mg, it is compound to contain Mn sulfide and oxide particle.On the other hand, under the situation of Mg content less than the oxide particle of 10 quality %, sulfide can not be compound with it but Individual existence.In order to sum up, find by be not less than the Mg of 10 quality % to oxide particle, contain Mn sulfide can be stably compound and deposition is thereon with the oxide particle of 0.5-10 micron.As its result, can guarantee the IGF phase transformation nucleus that is not less than 10/square millimeter 0.5-10 micron and contains the Mn that is not less than 0.3 quality % with the complex form of oxide compound and sulfide.Yet, should be noted that if total add-on of Ca, REM and Zr greater than 0.02 quality %, Mn no longer be incorporated into oxide compound compound sulfide in, cause that Mn content is reduced to less than 0.3 quality % in the compound particle.
Fig. 1 (c) is expression to its synoptic diagram in conjunction with the HAZ structure of using (1) of explaining above and (2) technology.Except the refinement of GBF crystal grain and FSP crystal grain owing to produce a large amount of IGF crystal grain, refinement the HAZ structure.If the alloying constituent quantity not sufficient that adds, the MA amount of generation increases, and reduces the CTOD performance.So, must improve the CTOD performance by being used in combination (3) of explained later consistently.
To explain (3) the measure that obtains below.As everyone knows, the behavior of generation MA depends on its hardenability and speed of cooling to a great extent in HAZ.In the present invention, the hardenability of HAZ is influenced by the composition of steel not only to a great extent, and influenced by the size of γ crystal grain and the ability of generation IGF thereof.Under the situation of conventional steel,, do not consider that almost the size of γ crystal grain and IGF thereof produce ability about the hardenability of HAZ.On the other hand, in the steel of the present invention, γ crystal grain is littler, in addition, it is higher that IGF produces ability, causes on the γ crystal boundary and the increase of γ intragranular phase transformation position, this steel of the present invention has the significantly reduced feature of hardenability of HAZ with respect to the conventional steel with identical chemical constitution.About having the steel of the present invention of this feature, with the scope of the speed of cooling of carrying out using in the welding of offshore structure and C of the present invention and Mn as prerequisite, broad research alloy content effect that MA is produced.As a result, following 2 obvious:
4. Nb content increases to than higher in the past level and almost can not increase the MA amount that produces in HAZ.
But the relation that 5. a kind of discontinuous strong dependency is arranged between the amount of the MA in Cu, Ni, Cr and Mo total amount and HAZ.
4. find out from the, increase to 0.05 quality % even have been found that Nb content, it is not obvious to the effect of the MA amount that produces among the HAZ.For the example of the actual Nb of use in the conventional steel plates that is given in offshore structure (guaranteeing the steel of CTOD for weld seam), under the situation of " the 12nd OMAE international conference collection of thesis, 1993; Glasgow, UK, ASME; III-A volume; 207-214 page or leaf ", 0.02 quality % is the upper limit of Nb in the steel of 420MPa level yield strength, at " the 12nd OMAE international conference collection of thesis; 1993; Glasgow, UK, ASME, the III-A volume, the 199-205 page or leaf " situation under, 0.021 quality % is the upper limit of Nb in the steel of 460MPa level yield strength, at " the 12nd OMAE international conference collection of thesis, 1993, Glasgow, UK, ASME, the III-A volume, the 307-314 page or leaf " situation under, for the steel of 420MPa level yield strength, Nb is 0.024 quality %.As mentioned above, the Nb content on the 0.02 quality % order of magnitude is the upper limit substantially.On the contrary, the present invention has the advantage that can effectively use the Nb of maximum 0.05 quality %.
The 5., have been found that when Cu, Ni, Cr and Mo total amount surpass 3 quality % the MA amount among the HAZ increases suddenly from.Obtained to form the governing principle of design from above-mentioned discovery, for example, increase to 76.2 millimeter magnitudes and keep yield strength to be not less than 460MPa at plate thickness, particularly under the situation of 500-550MPa level, utilize the underlying metal intensity of Nb increase as much as possible, reduce simultaneously and quicken Cu, Ni, Cr and the Mo that MA produces than slab.Simultaneously, aspect cost of alloy, the minimizing of Cu, Ni, Cr and Mo is wished.
Fig. 1 (d) is expression to its synoptic diagram in conjunction with the HAZ structure of using above-mentioned (3) technology and (1) and (2) technology.The HAZ structure is by fully refinement, and the MA amount is stable reduces, so, for higher intensity, obtained the CTOD performance of gratifying weld seam.Therefore, by implement (1) simultaneously, the technology of (2) and (3), the present invention becomes feasible.
The reason of restriction chemical ingredients will be described below.In the description of following chemical ingredients, % refers to quality %.
For intensity and the toughness that guarantees underlying metal and HAZ, it is essential being not less than 0.04% C.Yet if C content surpasses 0.14%, the toughness of underlying metal and HAZ reduces, and weldability reduces simultaneously, so, the 0.14%th, the upper limit.
For deoxidation, can add Si.Yet if Si surpasses 0.4%, HAZ toughness reduces.In the present invention, Al, Ti or Mg also can be used for deoxidation, so from HAZ toughness aspect, Si content should be as far as possible little.Because Si promotes the MA among the HAZ to produce, so for the present invention, it is a kind of undesirable element.
It is essential being not less than 1% Mn, to guarantee the intensity of underlying metal and HAZ.Simultaneously, Mn is important for forming the sulfide that constitutes IGF phase transformation nucleus.Yet, if Mn content greater than 2.0%, underlying metal and HAZ become fragile, simultaneously weldability reduces, so, the 2.0%th, the upper limit.
For the present invention, P is a kind of impurity element, in order to guarantee the quality of gratifying underlying metal and HAZ, must be reduced to below 0.02%.
For the present invention, S is a kind of essential element, on oxide particle with complex form deposition sulfide as the IGF nucleus, being not less than 0.001% S must guarantee.Yet, if S content greater than 0.005%, the toughness of underlying metal and HAZ reduces, so, the 0.005%th, the upper limit.
Nb is very effective improving underlying metal intensity and the toughness of HAZ is reduced aspect minimizing.Simultaneously, Nb also is being effective aspect the refinement raising toughness of underlying metal structure.For example, for 76.2 millimeters thickness of slab, in order to obtain gratifying underlying metal toughness and to obtain the yield strength of 500MPa level, it is necessary being not less than 0.005% Nb.Yet, if Nb content greater than 0.05% because MA amount increases or owing to precipitation hardening reduces the toughness of HAZ, so, the 0.05%th, the upper limit.In order successfully to make according to underlying metal of the present invention, Nb is the element that should use certainly, hope be effectively to utilize to be not less than 0.02% Nb.
Al is with Mg, forms the superfine oxide particle of 0.01-0.1 micron, and is deposited in TiN on the oxide particle with complex form jointly as the pinning particle, and is further used as the phase transformation crystal grain of GBF particle and FSP crystal grain, thus refinement HAZ structure.In order to realize this point, it is essential being not less than 0.001% Al.If Al is less than 0.001%, in order to obtain to be not less than 10,000/square millimeter compound TiN particle and guarantee that the superfine oxide particulate quantity that requires is impossible is so it is not enough that the refinement of γ crystal grain and the phase transformation nucleus quantity on the γ crystal boundary become.As a result, GBF crystal grain and FSP crystal grain all do not have abundant refinement, have therefore reduced HAZ toughness.But, if Al greater than 0.01%, Al content increases in the oxide compound that constitutes IGF phase transformation nucleus, in order to offset this point, the Mg content in the oxide compound is reduced to below the 10 quality %.As a result, the sulfide that contains Mn is deposited on the oxide particle hardly, causes them to lose ability as IGF phase transformation nucleus, so, guarantee to be not less than 10/square millimeter the IGF phase transformation nucleus difficulty that becomes with stable manner.
As mentioned above, when IGF phase transformation nucleus quantity became deficiency, HAZ toughness reduced.Therefore, the upper limit of Al is 0.01%.
Ti is precipitated as TiN with the complex form that is of a size of the 0.01-0.5 micron on the superfine oxide particle, and as the pinning particle, and is further used as the phase transformation nucleus of GBF crystal grain and FSP crystal grain.For this reason, it is essential being not less than 0.005% Ti.If Ti is less than 0.005%, the TiN that assurance is not less than 10,000/square millimeter complex form is impossible.As a result, all fully refinements of GBF crystal grain and FSP crystal grain, thus reduce HAZ toughness.If Si and Al are near its lower limit, deoxidant element becomes inadequately sometimes, so, take over desoxydatoin in order to make Ti, wish that adding is not less than 0.01% Ti.Yet,, be settled out TiC or the alligatoring of TiN particle and arrive several microns big size, thereby make underlying metal and HAZ embrittlement if Ti surpasses 0.03%.For above-mentioned reasons, Ti on be limited to 0.03%.
Mg plays most important effect in the present invention.The main effect of Mg is the superfine oxide particle that forms the 0.01-0.1 micron with Al, with be deposited in TiN on the oxide particle with complex form jointly as the pinning particle, and be further used as the phase transformation nucleus of GBF crystal grain and FSP crystal grain, thereby refinement HAZ structure.The secondary role of Mg is by providing effect as the phase transformation nucleus to wherein introducing 10 quality % or more mostly being oxide particle, and the sulfide that quickens to contain Mn is with the precipitation of complex form on the oxide particle of 0.5-10 micron, thus refinement HAZ structure.In order to realize this two effects simultaneously, be not less than 0.0003%, it is necessary preferably being not less than 0.005%.If Mg is less than 0.0003%, the content of the Si in oxide compound, Al, Ti etc. increases, and in order to compensate this point, the Mg content in the oxide compound is reduced to below the 10 quality %.As a result, contain Mn sulfide and almost can not be deposited on the oxide particle, cause them to lose its ability, so it is not enough that IGF phase transformation nucleus quantity becomes as IGF phase transformation nucleus.Simultaneously, ultra-fine (Mg, Al) the oxide particle quantity difficulty that becomes that guarantees to require for obtaining to be not less than 10,000/square millimeter bonded TiN particle.Yet if Mg surpasses 0.005%, its metallography effect is saturated, so this value is confirmed as its upper limit.
O constitute have the HAZ pinning effect ultra-fine (Mg, Al) oxide particle, and it be formed in the IGF phase transformation nucleus among the HAZ the 0.5-10 micron contain the Mg oxide particle.In order to realize this two effects, it is essential being not less than 0.001% O.If 0 less than 0.001%, for obtain to be not less than 10,000/square millimeter bonded TiN particle and guarantee to be not less than 10/square millimeter the 0.5-10 micron oxide particle and guarantee the necessary superfine oxide amounts of particles difficulty that becomes.Yet, if O surpasses 0.005%, a large amount of thick oxide particles that produce greater than 10 microns, and their sources of beginning as brittle rupture among underlying metal or the HAZ, so, determine that 0.005% is the upper limit.
N form the complex form be of a size of the 0.01-0.5 micron ultra-fine (Mg, Al) sedimentary TiN on the oxide particle as the pinning particle, and are further used as the phase transformation nucleus of GBF crystal grain and FSP crystal grain, thus refinement HAZ structure.For this reason, it is essential being not less than 0.001% N.If N is less than 0.001%, the TiN particle that assurance is not less than 10,000/square millimeter complex form is impossible.But if N surpasses 0.01%, dissolved N increases, and causes underlying metal and HAZ embrittlement, and the reduction of the surface property of cast panel, so, determine that this value is the upper limit.
The reason of the element that interpretation is selected hereinafter.
Can add Ca, REM and Zr as reductor or sweetening agent.They are by reducing O content as reductor.As sweetening agent, they reduce S content and control the shape of sulfide.In order to improve the quality of underlying metal and HAZ by these effects, the content that requires every kind of element is 0.0005% or more.If these constituent contents are too big, they are sneaked in the IGF phase transformation nucleus, reduce the oxide compound and Mg content in the sulfide and the Mn content that constitute IGF phase transformation nucleus, and therefore, IGF phase transformation nucleus loses its effect.On this meaning, the upper limit of Ca, REM and Zr is respectively 0.005%, 0.01% and 0.01%, and the total amount that must limit these three kinds of elements is 0.02% or littler.Here, REM represents lanthanon, as La and Ce, even add the lucium metal that these elements mix composition, also can obtain above-mentioned effect.
Cu, Ni, Cr and Mo can be used to improve intensity, toughness, erosion resistance of underlying metal etc.For this reason, any content of these elements is necessary for 0.05% or more.Up to the present, under the situation of the intensity that must obtain underlying metal simultaneously and toughness raising and thickness range increase, use these elements certainly.In the present invention, the CTOD aspect of performance of collateral security HAZ wishes to reduce these elements on possible degree.On this meaning, the upper limit of Cu, Ni, Cr and Mo must control to 1.5%, 3.0%, 0.5% and 0.5% respectively, and in addition, the total amount of these elements must be adjusted to and be no more than 3.0%.If any one of these elements surpasses its upper limit, perhaps the total amount of these elements surpasses 3.0%, and the CTOD performance of HAZ obviously reduces.
V effectively improves the intensity of underlying metal and HAZ by precipitation strength.For this reason, it is essential being not less than 0.005% V.Yet if V content surpasses 0.05%, weldability and HAZ toughness reduce, so, determine 0.05% as the upper limit.
B is being effective aspect intensity that improves underlying metal and the toughness.For this reason, it is effective being not less than 0.0001% B.Yet if B content surpasses 0.003%, weldability obviously reduces, so, determine that 0.003% is the upper limit.
Steel of the present invention is through being adjusted to particular value to chemical constitution, and continuous casting becomes slab in the steelmaking process in Steel industry, by reheat, rolling, cooling and heat treatment process (these processes in all sorts of ways control), this slab is manufactured steel plate.For thickness is 76.2 millimeters slab for example, in order to obtain 460MPa, and the yield strength of 500-550MPa level preferably, using direct quenching or quicken cooling in rolling back is effectively, so that utilize Nb content most possibly.In addition, can regulate intensity and toughness by tempering.Simultaneously, can use the rolling and cooling casting slab never of heat supply.HAZ toughness is not only by chemical constitution but also by the decision of the dispersion state of pinning particulate dispersion state and IGF phase transformation nucleus.These particulate dispersion staties can not produce wide variation in making the underlying metal process.Therefore, the toughness of HAZ can not depend on the manufacturing processed of underlying metal very bigly, so reheat, each process rolling and heat treatment process can be any kinds.
The dispersion state of Shuo Ming inclusion is by those method quantitative measurments described below in the present invention.
The TiN amounts of particles of the 0.01-0.5 micron of the oxide compound that interior bag Mg and Al form is determined by following method: the sampling replica sample of the optional position of underlying metal steel plate is taken from preparation, use transmission electron microscope (TEM) 10,000-50, observation sample under 000 times the magnification, so that cover at least 1, the zone of 000 square micron, the measurement size TiN amounts of particles in pre-determined range, and be transformed into particle number on the unit surface (individual/square millimeter).Here, use the energy dispersive X-beta ray spectrum (EDS) be attached on the TEM by compositional analysis with use the crystal structure analysis of the image K-M of TEM to have TiN particulate (Mg, Al) evaluation of oxide particle.Can not measure for the chemical combination inclusion of all kinds that will measure if such evaluation is too complicated, simpler method below using, at first, square inclusion is considered to the TiN particle, and measuring wherein has inclusion and the size TiN particulate quantity in pre-determined range.Then,, measure its quantity by this method, identify in detail, determine wherein (Mg, Al) oxide compound and TiN compound ratio according to process described above about at least 10 particles in sedimentary TiN particle with complex form.After this, the sedimentary TiN amounts of particles of measuring earlier of complex form multiply by this ratio.If the carbide particle in the steel hinders above-mentioned tem observation, by 500 ℃ or more the thermal treatment of low temperature assemble and the alligatoring carbide particle, can make the observation of predetermined complex inclusion easier.
By method as described below, can measure by making oxide compound and the amounts of particles that contains the 0.5-10 micron that Mn sulfide is compounded to form.At first, prepare polishing sample with high polishing surface by a pat of on the optional position of underlying metal steel plate, downcutting, use opticmicroscope, 1, observe sample under 000 times the magnification, so that cover at least 3 square millimeters area, the amounts of particles of measurement size in pre-determined range, and a quantity of measuring is transformed into the granule number (individual/square millimeter) of unit surface.Then, from same sample, choose and particles that size at least 10 in pre-determined range choose immediately use the wavelength scattered x-ray spectrum (WDS) that is attached on the scanning electronic microscope (SEM) to carry out compositional analysis.Here,, from analytical value, remove Fe, determine that then particulate forms if in these particulate analytical values, detect Fe in the underlying metal.In measured particle, wherein detect O and S simultaneously and comprise the particle that is not less than 0.3 quality %Mn and be considered to be effective as IGF phase transformation nucleus, thereby determined the ratio of IGF phase transformation nucleus and 0.5-10 micron particle.The granule number of measuring earlier by opticmicroscope multiply by this ratio.As a kind of simpler method,, thereby measured the wherein quantity of O, S and the common 0.5-10 micron particle that exists of Mn three kinds of elements at the enterprising row element distribution measuring of said sample.
Embodiment
The chemical constitution of table 1 expression continuous casting steel, the toughness of quality of materials, welding conditions and every kind of HAZ of the thickness of every kind of steel plate of table 2 expression, its manufacture method, pinning amounts of particles, IGF phase transformation nucleus quantity, underlying metal.
Steel of the present invention has the thickness of slab of 38.1-76.2 millimeter, underlying metal yield strength (YS) is 510-570MPa, in the multirun weld joining region (CGHAZ) that the welding heat input by used for submerged arc welding 3.5-10.0kJ/mm obtains, at-10 ℃ of gratifying CTOD that have greater than 0.2 millimeter.
On the other hand, because inappropriate chemical constitution, for 76.2 millimeters thickness of slab, compared steel is all poor aspect underlying metal quality or HAZ quality.Steel 12 is because S makes IGF phase transformation nucleus quantity not sufficient, HAZ poor toughness very little.Steel 13 is wanting in underlying metal toughness and HAZ toughness because the S amount is too big.Steel 14 is because Nb content is wanting in the intensity and the toughness of underlying metal very little.Steel 15 is wanting in HAZ toughness because Nb content is too big.Steel 16 makes pinning amounts of particles deficiency because the Al amount is too little, and is relatively poor aspect HAZ toughness.Steel 17 makes IGF phase transformation nucleus quantity not sufficient because the Al amount is too big, and is relatively poor aspect HAZ toughness.Steel 18 makes pinning amounts of particles deficiency because the Ti amount is too little, and is relatively poor aspect HAZ toughness.Steel 19 is relatively poor aspect underlying metal toughness and HAZ toughness because the Ti amount is too big.Steel 20 and steel 21 are too little because of Mg and O quantity respectively, and in pinning amounts of particles and IGF phase transformation nucleus quantitative aspects deficiency, relatively poor aspect HAZ toughness.Steel 22 makes pinning amounts of particles deficiency because N content is too little, and is relatively poor aspect HAZ toughness.Steel 23 is relatively poor aspect HAZ toughness because the total amount of Cu, Ni, Cr and Mo is too big.Steel 24 makes IGF phase transformation nucleus quantity not sufficient because the total amount of Ca, REM and Zr is too big, and is relatively poor aspect HAZ toughness.
Table 1 (wt%)
Classification | Steel | ??C | ??Si | ??Mn | ????P | ????S | ??Nb | ??Al | ??Ti | ??Mg | ????O | ????N | Other | Ca+ REM+ Zr | Cu+ Ni+ Cr+ Mo |
Steel of the present invention | ????1 | ?0.10 | ?0.03 | 1.48 | 0.006 | 0.003 | 0.02 | 0.002 | 0.025 | 0.002 | 0.004 | 0.008 | Ni:0.4,Cu:0.4,Mo:0.1 | 0 | ??0.9 |
????2 | ?0.08 | ?0.02 | 1.53 | 0.003 | 0.002 | 0.03 | 0.003 | 0.017 | 0.0003 | 0.004 | 0.002 | Ni:0.5,Cu:0.5,V:0.01 | 0 | ??1.0 |
????3 | ?0.05 | ?0.08 | 1.55 | 0.003 | 0.003 | 0.03 | 0.003 | 0.015 | 0.003 | 0.002 | 0.003 | Ni:0.7,Cu:0.6 | 0 | ??1.3 |
????4 | ?0.09 | ?0.06 | 1.55 | 0.003 | 0.003 | 0.04 | 0.002 | 0.016 | 0.002 | 0.003 | 0.002 | Ni:0.6,Cu:0.6 | 0 | ??1.2 |
????5 | ?0.08 | ?0.09 | 1.88 | 0.004 | 0.002 | 0.03 | 0.003 | 0.010 | 0.003 | 0.002 | 0.003 | Ni:1.0,Cu:0.6 | 0 | ??1.6 |
????6 | ?0.10 | ?0.08 | 1.57 | 0.015 | 0.002 | 0.02 | 0.003 | 0.009 | 0.002 | 0.004 | 0.004 | Ni:0.4,Cr:0.4,Ca:0.0007 | 0.0007 | ??0.8 |
????7 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:0.6,?Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????8 | ?0.11 | ?0.25 | 1.60 | 0.005 | 0.004 | 0.04 | 0.006 | 0.008 | 0.004 | 0.001 | 0.004 | | 0 | ??0 |
????9 | ?0.11 | ?0.25 | 1.60 | 0.005 | 0.004 | 0.04 | 0.008 | 0.008 | 0.004 | 0.001 | 0.004 | Ca:0.002,Zr:0.001 | 0.003 | ??0 |
????10 | ?0.13 | ?0.25 | 1.10 | 0.005 | 0.004 | 0.04 | 0.006 | 0.006 | 0.0004 | 0.001 | 0.004 | REM:0.004,B:0.001 | 0.004 | ??0 |
????11 | ?0.13 | ?0.25 | 1.10 | 0.005 | 0.004 | 0.04 | 0.006 | 0.006 | 0.004 | 0.001 | 0.004 | REM:0.004 | 0.004 | ??0 |
Compared steel | ????12 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.0008 | 0.02 | 0.005 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????13 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.006 | 0.02 | 0.005 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????14 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.003 | 0.005 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????15 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.06 | 0.005 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????16 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.0008 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????17 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.012 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????18 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.003 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????19 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.033 | 0.002 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????20 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.009 | 0.0001 | 0.003 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????21 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.009 | 0.002 | 0.0007 | 0.005 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????22 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.009 | 0.002 | 0.003 | 0.0007 | Ni:0.6,Cu:0.6,Ca:0.002 | 0.002 | ??1.2 |
????23 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.009 | 0.002 | 0.003 | 0.005 | Ni:2.0,Cu:0.8,Mo:0.3 | 0 | ??3.1 |
????24 | ?0.10 | ?0.20 | 1.59 | 0.004 | 0.001 | 0.02 | 0.005 | 0.009 | 0.002 | 0.003 | 0.005 | Ca:0.02,REM:0.01,Zr:0.01 | 0.022 | ??0 |
Analyze Mg with chemical analysis
Table 2
Classification | Steel | Thickness of slab (mm) | The manufacture method of plate
1) | Pinning particulate quantity
2)(individual/square millimeter)
| The quantity of IGF phase transformation nucleus
3)(individual/square millimeter)
| The underlying metal quality
4) | Welding conditions
5) | The CTOD of CGHAZ
6) |
????YS ???(MPa) | ??TS ??(MPa) | RAZ (%) | vTrs (℃) | Welding heat input (kJ/mm) | CTOD is in-10 ℃ (mm) | CTOD is in-30 ℃ (mm) |
Steel of the present invention | ????1 | ????76.2 | ????DQ-T | ????30000 | ????30 | ??550 | ??610 | ??60 | ??-75 | ????10.0 | ????0.9 | ????0.6 |
????2 | ????76.2 | ????DQ-T | ????20000 | ????30 | ??560 | ??640 | ??65 | ??-80 | ????3.5 | ????0.8 | ????0.7 |
????3 | ????38.1 | ????DQ-T | ????40000 | ????20 | ??510 | ??570 | ??70 | ??-80 | ????5.0 | ????1.0 | ????0.9 |
????4 | ????76.2 | ????DQ-T | ????40000 | ????25 | ??560 | ??630 | ??60 | ??-90 | ????3.5 | ????0.9 | ????0.5 |
????5 | ????76.2 | ????DQ-T | ????50000 | ????20 | ??570 | ??680 | ??65 | ??-70 | ????4.5 | ????0.7 | ????0.5 |
????6 | ????76.2 | ????ACC | ????100000 | ????40 | ??530 | ??650 | ??60 | ??-70 | ????3.5 | ????0.8 | ????0.6 |
????7 | ????50.8 | ????ACC | ????80000 | ????30 | ??530 | ??670 | ??60 | ??-70 | ????3.5 | ????0.8 | ????0.5 |
????8 | ????76.2 | ????DQ-T | ????15000 | ????15 | ??520 | ??600 | ??65 | ??-80 | ????3.5 | ????0.8 | ????0.6 |
????9 | ????76.2 | ????DQ-T | ????20000 | ????20 | ??520 | ??590 | ??60 | ??-60 | ????3.5 | ????1.1 | ????0.8 |
????10 | ????76.2 | ????ACC | ????15000 | ????15 | ??510 | ??580 | ??65 | ??-60 | ????3.5 | ????0.9 | ????0.7 |
????11 | ????76.2 | ????ACC | ????15000 | ????15 | ??510 | ??580 | ??65 | ??-60 | ????3.5 | ????0.9 | ????0.5 |
Compared steel | ????12 | ????76.2 | ????ACC | ????80000 | ????8 | ??530 | ??670 | ??60 | ??-70 | ????3.5 | ????0.15 | ????0.05 |
????13 | ????76.2 | ????ACC | ????80000 | ????30 | ??530 | ??670 | ??40 | ??-40 | ????3.5 | ????0.15 | ????0.05 |
????14 | ????76.2 | ????ACC | ????80000 | ????30 | ??450 | ??580 | ??60 | ??-40 | ????3.5 | ????0.9 | ????0.4 |
????15 | ????76.2 | ????ACC | ????80000 | ????30 | ??560 | ??680 | ??50 | ??-60 | ????3.5 | ????0.1 | ????0.03 |
????16 | ????76.2 | ????ACC | ????7000 | ????30 | ??530 | ??670 | ??60 | ??-70 | ????3.5 | ????0.1 | ????0.05 |
????17 | ????76.2 | ????ACC | ????90000 | ????7 | ??530 | ??670 | ??60 | ??-70 | ????3.5 | ????0.1 | ????0.05 |
????18 | ????76.2 | ????ACC | ????8000 | ????30 | ??520 | ??670 | ??60 | ??-60 | ????3.5 | ????0.07 | ????0.05 |
????19 | ????76.2 | ????ACC | ????80000 | ????30 | ??550 | ??680 | ??50 | ??-30 | ????3.5 | ????0.1 | ????0.03 |
????20 | ????76.2 | ????ACC | ????6000 | ????6 | ??530 | ??670 | ??60 | ??-70 | ????3.5 | ????0.05 | ????0.01 |
????21 | ????76.2 | ????ACC | ????7000 | ????7 | ??530 | ??670 | ??60 | ??-70 | ????3.5 | ????0.05 | ????0.02 |
????22 | ????76.2 | ????ACC | ????7000 | ????30 | ??520 | ??670 | ??60 | ??-60 | ????3.5 | ????0.13 | ????0.08 |
????23 | ????76.2 | ????ACC | ????80000 | ????30 | ??580 | ??720 | ??50 | ??-50 | ????3.5 | ????0.02 | ????0.01 |
????24 | ????76.2 | ????ACC | ????80000 | ????5 | ??530 | ??670 | ??65 | ??-60 | ????3.5 | ????0.05 | ????0.01 |
Table 2 is annotated
1) DQ: direct quenching, ACC: quicken cooling, T: tempering, CR: controlled rolling
2) wrap the TiN particle of the 0.01-0.5 micron of the oxide compound of forming by Mg and Al in
3) there is and contains the 0.5-10 micron particle that is not less than 0.3 quality %Mn in the complex form with oxide compound and sulfide
4) at the central position of thickness of slab test YS, TS and vTrs; RAZ is the mean value of 3 samples
5) weld by the multilayer of union-melt weld, V groove
6) obey BS7448, do not have PWHT, the Schwellenwert of 3 samples of expression, CGHAZ is the abbreviation of coarse-grain HAZ, cuts tired otch on the welded bonds on the I groove side