CN102676931A - Composite micro-alloy medium and high carbon steel - Google Patents
Composite micro-alloy medium and high carbon steel Download PDFInfo
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- CN102676931A CN102676931A CN2012101880404A CN201210188040A CN102676931A CN 102676931 A CN102676931 A CN 102676931A CN 2012101880404 A CN2012101880404 A CN 2012101880404A CN 201210188040 A CN201210188040 A CN 201210188040A CN 102676931 A CN102676931 A CN 102676931A
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Abstract
The invention relates to medium and high carbon steel, which comprises the following components in percentage by weight: 0.51-0.54 percent of C, 0.65-0.69 percent of Mn, 0.40-0.58 percent of Si, 0.03-0.07 percent of Nb, 0.1-0.13 percent of V, 0.20-0.3 percent of Cr, less than or equal to 0.020 percent of P, less than or equal to 0.015 percent of S and the balance of Fe, and is prepared through the following manufacturing process consisting of the following steps of: (1) preparing the raw materials according to the weight ratio of the components of a casting finished product; (2) selectively smelting in a 0.75 t intermediate frequency coreless induction electric furnace, heating to 1,100-1,180 DEG C, preserving heat for 1 hour and then performing forge forming; (3) normalizing a steel blank obtained by the step (2) at 850-900 DEG C and preserving heat for 1 hour, then performing air cooling or water spray cooling to room temperature, guaranteeing that the cooling speed is controlled within a range of 6-12 DEG C/s, and making sure that room temperature structures are ferrite and pearlite. The Nb and V-containing medium and high carbon steel material has the mechanical properties of high strength and high toughness.
Description
Technical field
The present invention relates to the medium and high carbon steel material, particularly a kind of design of Nb medium and high carbon steel composition and working method thereof of containing.
Background technology
There are some problems aborning in traditional thermal treatment medium and high carbon steel, mainly comprises: tread and wheel rim crystal grain are thick and inhomogeneous, are prone to produce bainite and the hard phase constitution of martensite, and ferrite content is very few, and the pearlitic grain distribution of sizes is unequal.Finally cause the inaccessible standard-required of its performance in the industrial production.
Single interpolation Nb or V or Ti element can combine with [C], [N] to generate carbide, nitride and carbonitride in steel, and these compounds at high temperature dissolve, and separate out grain growth and the precipitation strength effect of suppressing of playing at low temperatures.Its tissue is a ferritic---perlite, the ys under the state of cooling is considerably beyond 500MPa.Directly handle and high-intensity combination early stage; Consequently carbon equivalent reduces; And the intensity of steel and toughness improve greatly, and have significant cost advantage, make this type steel become the substitute products of the expensive quenching/tempered steel of cost; Induce one to annotate day and become, obtained application comprising under many occasions of trolley part.Traditional micro-alloying technology is own through being used for the organizational controls of rolled plate product; Nb is the first excellent element in these products, and Nb adds in the steel as microalloy element, mainly still plays precipitation strength and refined crystalline strengthening effect; Separate out 900～1000 degrees centigrade of forms with NbC or Nb (NC); Because it is higher that it separates out temperature, therefore can stop growing up of austenite matrix, thus crystal grain thinning.Precipitation strength is one of the most weak schedule of reinforcement of rising yield tensile ratio, and refined crystalline strengthening is the schedule of reinforcement that unique embrittlement vector is a negative value.Therefore the Nb element is good strengthening element, but its weakness also clearly, because Nb is solid-solubilized in the hardening capacity that can improve steel in the ferritic strongly; Therefore in the low-carbon (LC) steel of big specification, use less; Because occur abnormal structure (B, M) easily, such as in reinforcing bar, large diameter reinforcing bar generally is partial to use V alloyization; The processing range of Nb alloying is very narrow, in industrial production, is difficult for realizing.And, although the microalloyed steel of quality adjustment condition is competitive aspect intensity, yet, to compare with quenching/tempered steel, when being tempered to same hardness, its toughness is on the low side.
Except that the introduction of above-mentioned single interpolation micro alloying element, also do not see the research report to the compound interpolation micro alloying element of medium and high carbon steel.
Summary of the invention
The present invention provides the composition design of the medium and high carbon steel of compound interpolation Nb and V microalloy element, and has combined suitable thermal treatment process through a large amount of experiments, and realization organizes size tiny and be evenly distributed, and has higher-strength and flexible product.
The present invention has adopted following technical scheme: a kind of medium and high carbon steel, and its component percentages is: C:0.51-0.54 %, Mn:0.65-0.69%, Si:0.40-0.58%; Nb:0.03-0.07%, V:0.1-0.13%, Cr:0.20-0.3%; P :≤0.020%, S :≤0.015%, surplus is Fe.
Concrete ME of the present invention comprises following step:
1) components by weight according to casting finished products disposes raw material:
2) be chosen at melting in the 0.75 t intermediate frequency coreless induction furnace, be heated to 1100 ~ 1180 ℃ and be incubated 1 hour after, forging molding;
3) with step 2) obtain steel billet after 850-900 ℃ of normalizing is incubated 1 hour, carry out air cooling or water spray and be cooled to room temperature, guarantee that speed of cooling is controlled in the scope of 6-12 ℃/s, guarantee that room temperature texture is ferritic and perlite.
The effect of each alloying element is following among the present invention:
C: guarantee the hardening capacity of steel, improve intensity, hardness and the wear resistance of steel, require mainly to consist of perlite in the tissue of steel alloy, the best content design of C is in 0.51 ~ 0.54% scope, and at this moment, the proportioning of perlite soft or hard phase is optimum, and performance is best.
Mn: improve the intensity and the toughness of steel, Mn has stronger solid solution strengthening effect, can reduce the transformation temperature of steel, alleviates austenite to pearlitic velocity of transformation, improves the hardening capacity of steel, and can crystal grain thinning, improves intensity and toughness.But improve Mn content and will improve pearlitic volume(tric)fraction, reduce the toughness of steel, for ensureing the better strength and toughness proportioning, design Mn composition range is 0.65-0.69%.
Si: solid solubility is bigger in steel, remarkable reinforced ferrite, and its solid solution strengthening effect is higher than Mn, and the increase of Si can improve ferritic volume(tric)fraction in the steel, and crystal grain is attenuated, and helps improving the toughness of steel, and design Si composition range is 0.40-0.58%.
Nb and V:Nb and V all are micro alloying elements, and compound interpolation micro alloying element V-Nb is owing to there is compound action can control the ability of austenite grain size and precipitation strength.The present invention has selected the set of dispense ratio of corresponding N b and V through a large amount of experiments, makes the Nb and the V that add help grain-size control and improve intensity, Nb, and (C, N) the final dissolving of phase can produce the common precipitating reinforcing effect of V and Nb to V in process of cooling.The steel that perhaps contains V with straight carbon steel is compared, and the steel that adds the V+Nb of said ratio has kept very tiny austenite grain size.The microalloying precipitate that has disperse to distribute in the ferritic in the microalloyed steel that obtains, its shape characteristic is austenitic alternate degradation production, and tiny alternate disperse distribution phase is arranged in the V+Nb steel.
About austenitizing temperature, through experiment, the hardness of cooled steel alloy is influenced by austenitizing temperature to a great extent, and when austenitizing temperature was 1100 ~ 1180 ℃, hardness had only small fluctuation over time.The V+Nb steel is after long-time insulation cooling, and the variation of its hardness shows: the trend that hardness depends on temperature reduces.
About speed of cooling, guarantee that speed of cooling is controlled in the scope of 6-12 ℃/s, be ferritic and perlite to guarantee room temperature texture.When cooling rate was lower than 6 ℃/s, the high speed wheel hardness of steel of the design's composition was low excessively, can not satisfy the safety in production requirement; When cooling rate is higher than 12 ℃/s, be prone to mixed crystal phenomenon in the tissue, ratio of ferrite is not enough, and toughness properties is unstable.
The composition of the medium and high carbon steel of compound interpolation Nb of the present invention and V microalloy element design, and combine suitable thermal treatment process, thus realize organizing size tiny and be evenly distributed and obtain the evenly tiny ferrite network and the tissue of pearlite colony.Under the condition of proof strength, improved the toughness of steel.Therefore; The mechanical property that the medium and high carbon steel material of Nb of containing of the present invention and V has HS, H.T. cooperates, and through the medium and high carbon steel that the present invention obtains, tensile strength is 760-980MPa; Ys is 480-590MPa; Elongation after fracture is 18-28%, and low temperature (20 ℃) ballistic works (Akv) are 16-222J, and room temperature can obtain the uniform formation that ratio of ferrite is 11-23%.
Embodiment
Embodiment 1:
The composition percentage composition of this kind microalloy medium carbon steel is: C:0.51 %, and Mn:0.65%, Si:0.40%, Nb:0.03%, V:0.1%, Cr:0.20%, P :≤0.020%, S :≤0.015%, surplus is Fe.
Concrete ME of the present invention comprises following step:
According to the components by weight of casting finished products configuration raw material, melting be heated to 1100 ℃ and be incubated 1 hour after, behind the forging molding; Steel is heated to 850 ℃; Be incubated 1 hour with its abundant austenitizing, air cooling makes average cooling rate be controlled to be 6 ℃/s to room temperature through measuring monitoring afterwards.Through Mechanics Performance Testing, its ys is 480MPa, and tensile strength is 760MPa, and elongation after fracture is 22.0%, and low temperature (20 ℃) ballistic works (Akv) are 16.7J.
Embodiment 2:
The composition percentage composition of this kind microalloy medium carbon steel is: C:0.53 %, and Mn:0.66%, Si:0.45%, Nb:0.05%, V:0.11%, Cr:0.25%, P :≤0.020%, S :≤0.015%, surplus is Fe.
After smelting, forging, steel is heated to 900 ℃, be incubated 1 hour with its abundant austenitizing, air cooling makes average cooling rate be controlled to be 10 ℃/s to room temperature through measuring monitoring afterwards.Through Mechanics Performance Testing, its ys is 495MPa, and tensile strength is 845MPa, and elongation after fracture is 22.3%, and low temperature (20 ℃) ballistic works (Akv) are 19.0J.
Embodiment 3:
The composition percentage composition of this kind microalloy medium carbon steel is: C:0.54 %, and Mn:0.69%, Si:0.58%, Nb:0.07%, V:0.13%, Cr:0.3%, P :≤0.020%, S :≤0.015%, surplus is Fe.
After smelting, forging, steel is heated to 900 ℃, be incubated 1 hour with its abundant austenitizing, water spray is cooled to room temperature afterwards, makes average cooling rate be controlled to be 12 ℃/s through measuring monitoring.Through Mechanics Performance Testing, its ys is 530MPa, and tensile strength is 890MPa, and elongation after fracture is 21.1%, and low temperature (20 ℃) ballistic works (Akv) are 19.5J.
Claims (1)
1. a composite micro-alloyed medium and high carbon steel is characterized in that, its component percentages is: C:0.51-0.54 %; Mn:0.65-0.69%, Si:0.40-0.58%, Nb:0.03-0.07%; V:0.1-0.13%, Cr:0.20-0.3%, P :≤0.020%; S :≤0.015%, surplus is Fe, and makes through following ME:
1) components by weight according to casting finished products disposes raw material:
2) be chosen at melting in the 0.75 t intermediate frequency coreless induction furnace, be heated to 1100 ~ 1180 ℃ and be incubated 1 hour after, forging molding;
3) with step 2) obtain steel billet after 850-900 ℃ of normalizing is incubated 1 hour, carry out air cooling or water spray and be cooled to room temperature, guarantee that speed of cooling is controlled in the scope of 6-12 ℃/s, guarantee that room temperature texture is ferritic and perlite.
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| CN2012101880404A CN102676931A (en) | 2012-06-08 | 2012-06-08 | Composite micro-alloy medium and high carbon steel |
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| CN2012101880404A CN102676931A (en) | 2012-06-08 | 2012-06-08 | Composite micro-alloy medium and high carbon steel |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102676932A (en) * | 2012-06-13 | 2012-09-19 | 唐海峰 | Preparation method of high carbon steel in composite microalloy |
| CN102876867A (en) * | 2012-10-17 | 2013-01-16 | 夏雨 | Heat treatment method of medium-high carbon steel |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0813028A (en) * | 1994-06-30 | 1996-01-16 | Kawasaki Steel Corp | Production of precipitation hardening steel material having high tensile strength and high toughness |
| CN101492787A (en) * | 2009-03-05 | 2009-07-29 | 芜湖三联锻造有限公司 | Medium-high-carbon microalloy non-hardened and tempered steel and controlled forging and cooling process |
| CN101812631A (en) * | 2010-04-09 | 2010-08-25 | 中国石油天然气集团公司 | Steel for expandable casing for oil well and manufacturing method thereof |
-
2012
- 2012-06-08 CN CN2012101880404A patent/CN102676931A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0813028A (en) * | 1994-06-30 | 1996-01-16 | Kawasaki Steel Corp | Production of precipitation hardening steel material having high tensile strength and high toughness |
| CN101492787A (en) * | 2009-03-05 | 2009-07-29 | 芜湖三联锻造有限公司 | Medium-high-carbon microalloy non-hardened and tempered steel and controlled forging and cooling process |
| CN101812631A (en) * | 2010-04-09 | 2010-08-25 | 中国石油天然气集团公司 | Steel for expandable casing for oil well and manufacturing method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102676932A (en) * | 2012-06-13 | 2012-09-19 | 唐海峰 | Preparation method of high carbon steel in composite microalloy |
| CN102876867A (en) * | 2012-10-17 | 2013-01-16 | 夏雨 | Heat treatment method of medium-high carbon steel |
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Application publication date: 20120919 |