CN100519814C - Non-hardened and tempered steel plate with high yield strength - Google Patents
Non-hardened and tempered steel plate with high yield strength Download PDFInfo
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- CN100519814C CN100519814C CNB2006100925741A CN200610092574A CN100519814C CN 100519814 C CN100519814 C CN 100519814C CN B2006100925741 A CNB2006100925741 A CN B2006100925741A CN 200610092574 A CN200610092574 A CN 200610092574A CN 100519814 C CN100519814 C CN 100519814C
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Abstract
This invention relates a high yield strength and non-hardened and lempered steel plate. It contains (mass percentages): C: 0.01-0.08%, Si: 0.05-0.5%, Mn: 0.5-2.5 %, Al: 0.01-0.07%, Cr: 0.05-1.5%, Mo: 0.05-1%, Ti: 0.005-0.03 %, B: 0.0005-0.003% and N: 0.002-0.008%. Its histology is of bainite with its island shaped martensite being limited (based area rate) lower than 1% (or %).
Description
Technical field
The present invention relates to a kind of steel plate of non-quenching and tempering type, particularly the steel plate that has useful high-yield strength as macrostructure thing purposes such as building construction or bridges.
Background technology
Steel plate for using as aforesaid macrostructure thing purposes except high strength, also requires high tenacity.In order to make the steel plate that satisfies these characteristics, in general after calendering, carry out the modifier treatment of Q-tempering.But, in this method, owing to after calendering, need heating treatment step once more, so the duration is elongated, and cost raises.So, expect to have the method for making of omitting once more heat treated and realizing the steel plate that the shortening of duration and cost reduce, as the technology that presents significant development in recent years the control calendering is arranged.In this technology, temperature when rolling by suitably controlling or draft etc. make the crystal grain miniaturization, are being guaranteed the intensity and the toughness of steel when rolling.In general this kind steel is known as non-hardened and tempered steel.
But the steel plate that the macrostructure thing that uses for the starting material as bridge etc. is used also requires high-yield strengthization.So conducts such as the inventor have improved the toughness of mother metal, and improve the non-quenched and tempered steel plate of yield strength, proposed the technology that the spy opens 2004-No. 149839 communiques.In this technology, by the one-tenth to steel in the middle of being grouped into particularly Nb and the solid solution capacity of B control closely, just can realize the high tenacityization and the high-yield strengthization of steel plate to a certain extent.But, utilize described look-ahead technique the yield strength that can realize be about 450～500MPa, expect further high-yield strengthization.
Summary of the invention
Given this present invention plants situation and finishes, and its purpose is, provides yield strength high non-quenched and tempered steel plate.
The inventor etc. open the technology of 2004-No. 149839 communiques for described spy, turn to purpose with the further high-yield strength that realizes steel plate, further investigate repeatedly.Found that,, and the metal structure of steel plate is made as the bainite of the generation that suppresses the island martensite body, then can further improve the yield strength of steel plate, thereby finish the present invention if the one-tenth of regulation steel is grouped into closely.
Promptly, so-called non-quenched and tempered steel plate of the present invention is meant, % represents with quality, contain: C:0.01～0.08%, Si:0.05～0.5%, Mn:0.5～2.5%, Al:0.01～0.07%, Cr:0.05～1.5%, Mo:0.05～1%, Ti:0.005～0.03%, B:0.0005～0.003% and N:0.002～0.008%, metal structure is for to represent to be suppressed at the bainite that (comprises 0%) below 1% with the island martensite body with area occupation ratio.
In addition, as other element, preferably contain from by
(1)Nb：0.005～0.03％
(2)V：0.005～0.05％
(3)Cu：0.05～3％
(4)Ni：0.05～3％
(5) element of selecting in a group that Zr:0.0005～0.005%, Mg:0.0003～0.005%, Ca:0.0005～0.005% and REM:0.0003～0.003% constitutes more than a kind etc.And remainder is Fe and unavoidable impurities.
According to the present invention, be grouped into by the one-tenth of regulation steel closely, and the metal structure of steel plate is made as the bainite of the generation that has suppressed the island martensite body, do not carry out the yet high steel plate of modifier treatment yield strength even just can provide.
Description of drawings
Fig. 1 is the MA growing amount in the steel of steel of the expression member condition that satisfies steel of the present invention and the chart of yield strength relation.
Fig. 2 be expression for the steel of the member condition that satisfies steel of the present invention, the chart of the MA growing amount when changing the speed of cooling after the hot rolling.
Embodiment
The inventor etc. open the technology of being put down in writing in 2004-No. 149839 communiques for described spy, turn to purpose with the further high-yield strength that realizes steel plate, study.The result shows, if the one-tenth of regulation steel is grouped into closely, and the metal structure of steel plate is made as bainite, then can becomes high strength (TS), if reduce the island martensite scale of construction that in this bainite structure, generates, then can realize high-yield strengthization (high YSization).At first, describe finishing fact of the present invention.
The inventor etc. are made as bainite by the metal structure with steel plate, have modulated some tensile strength (TS) and have been the steel plate of par, have measured the yield strength (YS) of each steel plate.Consequently, even TS is the steel plate of par, deviation is arranged also aspect YS.So the inventor etc. study the factor of YS of domination steel plate, find that the rate that exists of the YS of steel plate and the island martensite body in the bainite structure (following sometimes the island martensite body is called MA) has relation.Use accompanying drawing that this situation is described.
Fig. 1 is the chart of the relation of MA growing amount in the steel of steel of the expression member condition that satisfies steel of the present invention and yield strength.The variation of YS when Fig. 1 has represented to change MA growing amount in the steel, the metal structure in the steel is bainite, generating in this bainite structure has the island martensite body.And the TS of some A is 701MPa, and the TS of some B is 668MPa, and the TS of some C is 618MPa, and TS we can say and is par (60 キ ロ molten steel of JIS specification are flat).
Observe Fig. 1 and can find that when the MA growing amount in the steel reduced, YS had the tendency of raising, if particularly the MA growing amount reaches below 1%, then YS just reaches more than the 500MPa.On the other hand, the YS that generates the steel plate of a lot of island martensite bodies in bainite structure reduces.The inventor etc. think that the reason that YS reduces is that owing to the periphery at the island martensite body, dislocation is imported with high-density, so this dislocation reduces YS.
As mentioned above, in order to improve the yield strength of non-quenched and tempered steel plate, as long as reduce the MA growing amount in the bainite structure.Below with the present invention is described in detail.
At first, the metal structure to steel plate of the present invention describes.The metal structure of steel plate of the present invention is that the generation of island martensite body (MA) is suppressed in extremely low-level bainite.By forming this kind bainite structure, just can obtain the steel plate of high strength (TS).Promptly, so-called metal structure of the present invention is meant the tissue based on following bainite, promptly, metal structure integral body is being represented with area occupation ratio be made as under 100% the situation, tissue (for example ferrite) beyond the bainite is represented to be suppressed to less than 20% with area occupation ratio, and the area occupation ratio of bainite is (preferred more than 90%) more than 80%.
Like this, among the present invention, the generation by the MA in the middle of the inhibition metal structure just can prevent to import dislocation to high-density at the periphery of MA, thereby can improve the YS of steel plate.In addition, by suppressing the generation of MA, can also improve the toughness of mother metal.
Be made as 100% o'clock at the area with metal structure integral body, described MA (island martensite body) is made as below 1%, and is preferred below 0.8%, more preferably below 0.5%.
The metal structure of steel plate is after sample being carried out the corrosion of nitric acid ethanol, observes with opticmicroscope, calculates the area occupation ratio that metal structure integral body is made as 100% o'clock bainite.The observation multiplying power is made as 100 times and gets final product.The observation place of metal structure is when the thickness with steel plate is made as t, is located at the position of degree of depth t/4.Look-out station is made as 3, calculates the area occupation ratio of bainite structure after average.
The area occupation ratio of MA is after sample being carried out LePera (レ ペ ラ-) corrosion, observes with opticmicroscope, calculates the area occupation ratio that metal structure integral body is made as 100% o'clock MA.The observation multiplying power is made as 1000 times and gets final product.The observation place of metal structure is when the thickness with steel plate is made as t, is located at the position of degree of depth t/4.Look-out station is made as 3, calculates the area occupation ratio of MA after average.
Below, the one-tenth of steel plate of the present invention is grouped into describes.Significantly, steel plate of the present invention is represented with quality %, is contained: C:0.01～0.08%, Si:0.05～0.5%, Mn:0.5～2.5%, Al:0.01～0.07%, Cr:0.05～1.5%, Mo:0.05～1%, Ti:0.005～0.03%, B:0.0005～0.003% and N:0.002～0.008%.Stipulate the reasons are as follows of this kind scope.
C：0.01～0.08％
C is the intensity (TS and YS) in order to ensure mother metal and crucial element must contain 0.01% at least.Preferred more than 0.015%, more preferably more than 0.025%.But, when surpassing 0.08%, then because the diffusion quantitative change of C is many, C denseization partly easily when austenite phase transformation, so the growing amount of MA increases, and can't improve YS.In addition, when the hot rolling postcooling, do not generate bainite, and generate martensite easily, can't obtain gratifying base metal tenacity.Based on this kind situation, among the present invention, C content is made as below 0.08%.Preferred below 0.07%, more preferably below 0.055%.
Si：0.05～0.5％
Si suppresses the growing amount of MA and the element that improves yield strength.Si also is useful element as reductor in addition.In order to bring into play this kind effect effectively, need contain more than 0.05%.Preferred more than 0.1%.But when surpassing 0.5% and contain too much sometimes, then owing to can reduce base metal tenacity, so the upper limit is made as 0.5%.More preferably below 0.4%, further preferred below 0.3%.
Mn：0.5～2.5％
Mn improves hardenability and the element that helps the high strength (high TSization and high YSization) of steel plate.In addition, shown in aftermentioned among the present invention,, therefore can promote bainitic transformation to suppress the diffusion of C by improving hardenability owing to after hot rolling, quicken cooling.Thus, just can suppress denseization of C, suppress the generation of MA, thereby can further improve the yield strength of steel plate.Mn also has the bainite miniaturization is improved the element of the effect of base metal tenacity in addition.In order to bring into play this kind effect effectively, need contain the Mn more than 0.5%.Preferred more than 1%, more preferably more than 1.2%.But when Mn content too much surpasses 2.5%, then, base metal tenacity is worsened significantly, therefore should be suppressed at below 2.5% because hardenability becomes too high.Preferred below 2.25%.
Al：0.01～0.07％
Al is useful element as reductor.In addition, Al by with B and usefulness, and the effect of the hardenability when having acceleration cooling after further raising utilizes the calendering that B obtains.By improving hardenability, just can be the same with described Mn, suppress the generation of MA, further improve the yield strength of steel plate.In order to bring into play this kind effect effectively, need contain more than 0.01%.Preferred more than 0.020%.But when containing too much sometimes above 0.07%, then alumina type non-metallic inclusion amount increases, and cleanliness factor reduces, and base metal tenacity worsens.More preferably be made as below 0.06%.
Cr：0.05～1.5％
Cr improves hardenability and the element that improves the intensity (TS and YS) of steel plate.In addition, identical by improving hardenability with described Mn, can reduce the growing amount of MA, help high-yield strengthization.In addition, still promote the miniaturization of bainite, help the element of the raising of base metal tenacity.In order to bring into play this kind effect effectively, need contain more than 0.05%.Preferred more than 0.4%, more preferably more than 0.7%.But, when surpassing 1.5%, then since the easy variation of anti-weld crack of the HAZ portion when particularly carrying out big heat input welding therefore be made as below 1.5%.Preferred below 1.2%.
Mo：0.05～1％
Mo is the element that improves hardenability, and is identical with described Cr, helps to improve the intensity (TS and YS) of steel plate, also helps high YSization in addition.Contain simultaneously with B by making it, the hardenability in the time of just can controlling the cooling after the calendering is with the intensity (TS) and the flexible balance optimizing of mother metal.In order to bring into play this kind effect, need contain more than 0.05%.Preferred lower value is 0.10%.But, when containing too much sometimes, then because the anti-weld crack variation of HAZ portion, therefore with 1% as the upper limit.Preferred below 0.8%, more preferably below 0.5%.
Ti：0.005～0.03％
Ti is a useful element aspect N in steel fixing easily and N chemical combination and form nitride, finally can increase solid solution B or solid solution Nb.Consequently, can improve hardenability and improve the intensity (TS and YS) of steel plate.In addition, Ti is also the same with described Mn, can suppress the generation of MA and helps further high-yield strengthization.In addition, Ti also plays thickization that suppresses the γ particle, prevents the effect of the deterioration of base metal tenacity.In order to bring into play this kind effect effectively, need contain more than 0.005%.Preferred more than 0.01%.But, when containing too much sometimes, then can cause the reduction of base metal tenacity on the contrary above 0.03%, therefore be made as below 0.03%.Preferred below 0.02%.
B：0.0005～0.003％
B is the element that improves hardenability, improves the intensity (TS and YS) of steel plate.In addition,, the growing amount of MA can be reduced, yield strength can be further improved as described Mn by improving hardenability.In addition, contain simultaneously with Mo by making it, the hardenability in the time of can controlling the acceleration cooling after the calendering is with the intensity (TS) and the flexible balance optimizing of mother metal.In order to bring into play this kind effect effectively, B need contain more than 0.0005%.Preferred more than 0.001%.But when containing too much sometimes above 0.003%, then owing to the base metal tenacity variation, so B content should be suppressed at below 0.003%.Preferred below 0.0025%.
N：0.002～0.008％
Performance effective function aspect N and Al or the Ti chemical combination and form nitride, the improving of the base metal tenacity that causes in miniaturization by tissue.In order to bring into play this kind effect effectively, need contain more than 0.002%.Preferred more than 0.003%.But when containing N too much, then owing to the toughness variation of welding metal, the hardenability of mother metal reduces, so N content need be controlled at below 0.008%.Preferred below 0.007%, more preferably below 0.006%.Recommendation makes N content the least possible.
Steel plate of the present invention is the steel plate that contains described composition, in addition, as required, also can contain other element.For example, can contain from by
(1)Nb：0.005～0.03％
(2)V：0.005～0.05％
(3)Cu：0.05～3％
(4)Ni：0.05～3％
(5) element of selecting in a group that Zr:0.0005～0.005%, Mg:0.0003～0.005%, Ca:0.0005～0.005% and REM:0.0003～0.003% constitutes more than a kind.In addition, though also can contain other element, as a rule, remainder is essentially Fe and unavoidable impurities (for example P or S etc.).And as unavoidable impurities, P that is allowed and the amount of S for example are P:0.020% following (comprising 0%), S:0.010% following (comprising 0%).
Nb：0.005～0.03％
Nb is by containing jointly with Mo, B, and the element of the hardenability when improving acceleration cooling after the calendering, can improve the intensity (TS and YS) of steel plate.In addition,, the growing amount of MA can be reduced, therefore high-yield strengthization can be realized owing to be accompanied by the improvement of hardenability.In addition, contain simultaneously with B by making it, the hardenability in the time of can controlling the acceleration cooling after the calendering is with the intensity (TS) and the flexible balance optimizing of mother metal.In order to bring into play this kind effect effectively, recommend to contain more than 0.005%.More preferably more than 0.01%.But when surpassing 0.03% and contain too much sometimes, then because thickization of bainite, base metal tenacity reduces on the contrary, so the upper limit is made as 0.03% and gets final product.More preferably below 0.025%.
V：0.005～0.05％
V is the element that plays a role effectively for the intensity that improves mother metal (TS and YS).In order to bring into play this kind effect effectively, contain more than 0.005% and get final product.More preferably more than 0.01%.But when containing too much sometimes, then because big heat is imported the reduction of HAZ toughness, so the upper limit is made as 0.05%.Be limited to below 0.04% on preferred.
Cu：0.05～3％
Cu is the element that plays a role effectively in order to utilize solution strengthening and precipitation strength to improve the intensity (TS and YS) of mother metal.In order to bring into play this kind effect effectively, preferably contain more than 0.05%.More preferably more than 0.2%.But,, then, therefore be made as below 3% because big heat input HAZ toughness reduces when containing too much sometimes.More preferably below 1%, further preferred below 0.6%, preferred especially below 0.5%.
Ni：0.05～3％
Ni is the element that plays a role effectively in order to improve base metal tenacity.In order to bring into play this kind effect effectively, preferably contain more than 0.05%.More preferably more than 0.2%.But when surpassing 3% and when adding too much, then owing to be easy to generate pit, so the upper limit preferably is made as 3%.More preferably below 2%, further preferred below 1.5%.
The element of from constitute by Zr:0.0005～0.005%, Mg:0.0003～0.005%, Ca:0.0005～0.005%, REM:0.0003～0.003% one group, selecting more than a kind
Owing in old austenite particle, separate out ZrO during cooling after big heat input welding of Zr, Mg and Ca
2Or low melting point oxides such as MgO, CaO, as nuclear bainitic transformation takes place with it, therefore with the bainite miniaturization.Be to make the destruction path complicated thus, improve big heat input welded H AZ flexible element.On the other hand, Ca and REM and the S chemical combination that exists in steel and form sulfide are to be present in the element that plays a role effectively aspect the contraction of S segregation portion of thickness of slab central part and the toughness in improvement micro-ly.
In order to bring into play this kind effect effectively, preferably contain: the Zr of (preferred especially more than 0.001%), (preferred especially below 0.003%) below 0.005% more than 0.0005%; The Mg of (preferred especially more than 0.001%), (preferred especially below 0.004%) below 0.005% more than 0.0003%; The Ca of (preferred especially more than 0.001%), (preferred especially below 0.004%) below 0.005% more than 0.0005%; The REM of (preferred especially more than 0.001%), (preferred especially below 0.01%) below 0.003% more than 0.0003%.
P:0.020% following (comprising 0%)
P is the element that base metal tenacity is exerted an influence, and when surpassing 0.020%, then because base metal tenacity variation significantly, so the upper limit is made as 0.020%.More preferably be controlled at below 0.010%.
S:0.010% following (comprising 0%)
S is also identical with described P, is the element that base metal tenacity is exerted an influence, and when content surpasses 0.010%, then owing to generating thick sulfide base metal tenacity is worsened, and therefore the upper limit is made as 0.010%.More preferably be suppressed at below 0.005%.
Steel plate of the present invention for example can be made as followsly.That is, can after control is rolled rightly, make by quickening cooling rightly.
Heating temperature during control calendering (hot rolling) is made as about 1000～1150 ℃.If steel billet is heated to be more than 1000 ℃, then, can suppress the over-drastic miniaturization of austenite particle diameter owing to can make Nb and B solid solution, therefore can improve hardenability.Thus, can prevent denseization of the partial C that the diffusion by C causes, can suppress the generation of MA and realize high-yield strengthization.More preferably be heated to be more than 1050 ℃.But, when Heating temperature surpasses 1150 ℃, then owing to thickization of γ particle, the base metal tenacity variation, so Heating temperature is made as below 1150 ℃.More preferably below 1100 ℃.
Though for rolling condition as long as roll warmed-up steel billet with draught arbitrarily, yet preferably be made as 45～70% from 860 ℃ to the draught that roll end temp.Because by being suppressed at below 70% from 860 ℃ of draught of temperature province to the calendering end temp, just can prevent the over-drastic miniaturization that the recrystallization by the austenite particle causes or in the austenite particle, import too much distortion, so the hardenability improvement.Thus, just can prevent denseization of the partial C that the diffusion by C causes, can suppress the generation of MA and realize high-yield strengthization.In addition, when the draught in this temperature province becomes too much, then, can not become tissue, be difficult to guarantee strength of parent (TS), so the upper limit of draught preferably be made as 70% based on bainite because the processing phase transformation is promoted that ferrite is separated out.More preferably below 65%.But, when draught is too small, the base metal tenacity reduction owing to thickization of bainite structure, so draught is made as more than 45%.More preferably more than 50%.
Described so-called draught is meant, the difference of the thickness of slab under the thickness of slab under 860 ℃ and the calendering end temp is with respect to the ratio of the thickness of slab under 860 ℃.That is, the draught the temperature province from 860 ℃ to the calendering end temp can utilize following (1) formula to calculate.
Draught (%)=[thickness of slab under (thickness of slab under the thickness of slab under 860 ℃-calendering end temp)/860 ℃] * 100 ... (1)
The calendering end temp is made as 770～700 ℃ and gets final product.Owing to be made as more than 700 ℃ by rolling end temp, just can prevent from the austenite particle, to import too much distortion, so hardenability improved.Thus, just can prevent denseization of the partial C that the diffusion by C causes, can suppress the generation of MA and realize high-yield strengthization.In addition, if less than 700 ℃, then owing to ferrite transformation is separated out ferrite by promotion, so metal structure just can not become bainite, is difficult to guarantee strength of parent (TS).Thus, the calendering end temp is recommended to be made as more than 700 ℃.More preferably more than 710 ℃.And the upper limit of calendering end temp is made as 770 ℃.By finishing calendering below 770 ℃, just can promote the miniaturization of bainite structure, guarantee base metal tenacity.Preferred below 750 ℃.
Acceleration cooling after the control calendering is ℃ for example to carry out 3 ℃/ scope more than the sec from calendering end temp to 400.Because by quicken cooling after hot rolling, therefore denseization of the C that the diffusion of the C in the time of just can preventing by austenite phase transformation causes can suppress the generation of MA.Just can improve yield strength thus.If generate more MA, then strengthen speed of cooling and get final product.More preferably 5 ℃/more than the sec, further preferred 7 ℃/more than the sec.
Use accompanying drawing that this situation is described.Fig. 2 is the steel of expression for the member condition that satisfies steel of the present invention, Heating temperature with hot rolling the time is made as 1100 ℃, to be made as 60% from 860 ℃ of draught to the calendering end temp, the calendering end temp is made as under 720 ℃ the situation chart of the MA growing amount when changing the speed of cooling after the hot rolling.As can see from Figure 2, if the speed of cooling after the increase hot rolling, then the MA growing amount has the tendency of minimizing.
In the method for making of the present invention, can make the steel plate of all thickness, can be that 20～100mm (particularly realizes high-yield strength 25～80mm) times at thickness for example.
Steel plate of the present invention is for example very useful as the starting material that macrostructure things such as building construction or bridge are used.
[embodiment]
Below, to utilize embodiment that the present invention is described in more detail, yet following embodiment limit example of the present invention, in the scope that can be fit to aforementioned aim described later, also can change and implement, they all are contained in the technical scope of the present invention.
The steel (remainder is Fe and unavoidable impurities) that utilizes the one-tenth shown in the following table 1 of usual method melting to be grouped into, made steel billet after, be heated to be 1000～1150 ℃, under the temperature shown in the following table 2, finish calendering and made steel plate.At this moment, the draught the temperature province from 860 ℃ to the calendering end temp is made as 45～70%.Then, finish the back to 400 ℃, cool off with the speed of cooling shown in the following table 2 from calendering.In the following table 2, represent Heating temperature respectively, draught, calendering end temp the temperature province from 860 ℃ to the calendering end temp, finish the back to 400 ℃ the speed of cooling and the thickness of slab of steel plate from calendering.
To each steel plate of gained, calculated the area occupation ratio of MA according to following step.To each steel plate of gained, take sample from 1/4 position of thickness of slab, carry out the Lapera corrosion, with observation by light microscope (1000 times of multiplying powers).The field of view number is made as 3, calculates the area occupation ratio with respect to metal structure integral body.The results are shown in the following table 2.
To the metal structure (remainder) of each steel plate of gained, take sample in addition, carry out the corrosion of nitric acid ethanol, with observation by light microscope (100 times of multiplying powers) from 1/4 position of thickness of slab.The field of view number is made as 3, the results are shown in the following table 2.In the table 2, B is meant said bainite among the present invention, is meant when metal structure integral body is made as 100%, and bainite represents to generate tissue more than 80% with area occupation ratio.But,, also contain tissue beyond the bainite (for example ferrite etc.) not damage the degree of effect of the present invention.On the other hand, B+F is meant when metal structure integral body is made as 100%, and as the tissue beyond the bainite, ferrite represents to generate tissue more than 20% with area occupation ratio.Because ferrite is represented to generate more than 20% with area occupation ratio, therefore just can't guarantee intensity (TS and YS).
Then, each steel plate of gained is carried out stretching experiment and impact experiment, estimated mother metal characteristic [tensile strength (TS), 0.2% endurance (YS) and toughness] with following main points.
(1) stretching experiment: take the JIS4 experiment slice and carried out stretching experiment from thickness of slab 1/4 position of each steel plate.In the stretching experiment, tensile strength and 0.2% endurance have been measured.Respectively with tensile strength (TS) more than 570MPa, 0.2% endurance (YS) more than 500MPa as qualified.
(2) impact experiment: take the JIS4 experiment slice and carried out the pendulum impact experiment from thickness of slab 1/4 position of each steel plate, try to achieve the plastic fracture rate, calculated fracture and changed critical temperature.With fracture change critical temperature (vTrs) in the situation below-60 ℃ as qualified (base metal tenacity is good).
Can followingly investigate according to table 2.No.1～10 have high strength (TS) and have high-yield strength (YS) for satisfying the steel plate of the important document of defined among the present invention.And for impact characteristics (base metal tenacity), also very good.On the other hand, No.11～20 are low for steel plate, the especially yield strength (YS) of the important document of defined in the discontented unabridged version invention.
Claims (6)
1. a non-quenched and tempered steel plate is characterized in that % represents with quality, contains:
C：0.01～0.08％、
Si：0.05～0.5％、
Mn：0.5～2.5％、
Al：0.01～0.07％、
Cr：0.05～1.5％、
Mo：0.05～1％、
Ti：0.005～0.03％、
B：0.0005～0.003％、
N:0.002～0.008% and
Fe and unavoidable impurities,
Metal structure is for to represent to be suppressed at the bainite that (comprises 0%) below 1% with the island martensite body with area occupation ratio.
2. non-quenched and tempered steel plate according to claim 1 wherein, contains Nb:0.005～0.03%.
3. non-quenched and tempered steel plate according to claim 1 wherein, contains V:0.005～0.05%.
4. non-quenched and tempered steel plate according to claim 1 wherein, contains Cu:0.05～3%.
5. non-quenched and tempered steel plate according to claim 1 wherein, contains Ni:0.05～3%.
6. non-quenched and tempered steel plate according to claim 1, wherein, contain from by
Zr：0.0005～0.005％、
Mg：0.0003～0.005％、
Ca:0.0005～0.005% reaches
Select in one group that REM:0.0003～0.003% constitutes more than a kind.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100925741A CN100519814C (en) | 2006-06-16 | 2006-06-16 | Non-hardened and tempered steel plate with high yield strength |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100925741A CN100519814C (en) | 2006-06-16 | 2006-06-16 | Non-hardened and tempered steel plate with high yield strength |
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| Publication Number | Publication Date |
|---|---|
| CN101089218A CN101089218A (en) | 2007-12-19 |
| CN100519814C true CN100519814C (en) | 2009-07-29 |
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