CN103147020A - Low-temperature tempered martensite ultrahigh-strength steel - Google Patents
Low-temperature tempered martensite ultrahigh-strength steel Download PDFInfo
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- CN103147020A CN103147020A CN2013100906488A CN201310090648A CN103147020A CN 103147020 A CN103147020 A CN 103147020A CN 2013100906488 A CN2013100906488 A CN 2013100906488A CN 201310090648 A CN201310090648 A CN 201310090648A CN 103147020 A CN103147020 A CN 103147020A
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Abstract
The invention discloses low-temperature tempered martensite ultrahigh-strength steel and belongs to the technical field of alloy steel. The low-temperature tempered martensite ultrahigh-strength steel is suitable for parts bearing impact load, in particular for the parts bearing high-speed collision. The low-temperature tempered martensite ultrahigh-strength steel comprises the following chemical components in percentage by weight: 0.35%-0.45% of C, 3%-6% of Ni, 2%-5% of Co, 1.5%-2.5% of Si, 1.5%-2.5% of Mn, 0.5%-1.25% of Cr, 0.5%-2.0% of Mo, 0.01%-0.05% of Nb, 0.01%-0.03% of Ti, not more than 0.005% of S, not more than 0.005% of P, not more than 20ppm of O, not more than 20ppm of N, and the balance being Fe. The low-temperature tempered martensite ultrahigh-strength steel has the advantages of high strength, good fracture toughness, low yield ratio and good economical effect.
Description
Technical field
The invention belongs to the steel alloy technical field, a kind of low-temperaturetempering martensite ultrahigh-strength steel particularly is provided.Be applicable to the to withstand shocks component of load particularly bear the parts of high velocity impact.The component material of the load that withstands shocks must have high intensity and toughness, also requires to have high strain-hardening index, to improve the Adiabatic Shear drag of material.This material also will have low yield tensile ratio, makes it keep lower yield strength when high-caliber tensile strength, to reduce the tendency of material cleavage fracture.
Background technology
Contain the martensite ultrahigh-strength steel of C after solution hardening obtains martensite, internal stress is larger, and this moment, the toughness of material was low, generally will could use through tempering.And the martensitic stucture that the martensite ultrahigh-strength steel that does not contain C obtains after solution hardening is softer, and undercapacity generally will generate the dispersion-strengthened second-phase through tempering and could improve intensity.The martensite ultrahigh-strength steel is broadly divided into two classes according to tempering temperature: 1. low-temperaturetempering, and tempering temperature is generally at 200～300 ° of C; 2. high tempering, tempering temperature is general 〉=450 ° of C.Table 1 is main component and the mechanical property of some common martensite ultrahigh-strength steel.
Main component and the mechanical property of some common martensite ultrahigh-strength steel of table 1
As seen from Table 1, the main drawback of low-temperaturetempering martensite ultrahigh-strength steel 4340 and 300M etc. is that fracture toughness property is lower.And high tempering martensite ultrahigh-strength steel, yield tensile ratio as serial in 18Ni and 14Co-10Ni series (HY180, AF1410, AerMet100) is higher and contain more noble element Co, and their production cost is improved, and is unfavorable for being widely used.And the lower HP9-4-20 of Co content and G90 etc., low cross-intensity can not adapt to the strength of materials is required higher parts.
In addition, above-mentioned two large class martensite ultrahigh-strength steel have significant difference on composition.Generally do not contain Co in the low-temperaturetempering steel, the content of Cr and Mo is lower, contains a small amount of Ni, Si and Mn.And in high temper steel, great majority contain a large amount of Ni and Co, and the content of Cr and Mo is apparently higher than the low-temperaturetempering steel, but Si and Mn content are extremely low.
Summary of the invention
The object of the present invention is to provide a kind of low-temperaturetempering martensite ultrahigh-strength steel, have the advantages such as the low and production cost of superelevation tensile strength and high fracture toughness property, yield tensile ratio is lower.
According to purpose of the present invention, we concrete solution are in conjunction with the composition characteristic of low-temperaturetempering and high tempering martensite ultrahigh-strength steel, to increase the content of Ni and Co on the basis of low-temperaturetempering steel, adjust the amount of Si and Mn, and compound Nb and the Ti of adding controls grain-size.Its concrete chemical composition (wt.%) is:
C: 0.35-0.45%, Ni:3-6%, Co:2-5%, Si:1.5-2.5%, Mn:1.5-2.5%, Cr:0.5-1.25%, Mo:0.5-2.0%, Nb:0.01-0.05%, Ti:0.01-0.03% requires: S≤0.005% simultaneously, P≤0.005%, O≤20ppm, N≤20ppm, all the other are Fe.
The foundation of Chemical Composition design is as follows in steel of the present invention:
C is one of main strengthening element of steel, the ε-carbide that distributes in conjunction with the formation disperse with Fe, Mo, Cr etc. under low tempered condition.But too much C can cause twin crystal martensite to form, and causes fracture toughness property and impelling strength to reduce, and makes the welding property variation.C content is at least 0.35%, and the upper limit is no more than 0.45%.
Ni can change the character of helical dislocation core in lath martensite, thereby improves the mobility of dislocation, improves the toughness of matrix.Ni and Cr, Mo can guarantee the necessary hardening capacity of steel simultaneously.But Ni content too much causes strength degradation.Ni content is at least 3.0%, and the upper limit is no more than 6.0%.
Cr, Mo Main Function are the hardening capacity that increases steel, and Mo can also improve the toughness of steel in addition.Cr content 0.5～1.25%, Mo content is comparatively suitable in 0.5～2.0% scope.
Ti, Nb form high (Ti, Nb) C phase of thermostability, distribute in the crystal boundary disperse, and the pinning crystal boundary prevents alloy grain coarsening in high-temperature homogenization and solution treatment.Ti content 0.01～0.03%, Nb content is comparatively suitable in 0.01～0.05% scope.
Si can delay ε-carbide to Fe
3C changes, and can stop ε-Carbide Coarsening, can improve intensity and alleviate the temper brittleness of alloy, makes the alloy can tempering in wider scope, causes at most toughness to descend but add.The content of Si is at least 1.5%, and the upper limit is no more than 2.5%.
Mn can promote residual austenite to generate, and can put forward heavy alloyed toughness, but cause the reduction of intensity, and Mn can carry heavy alloyed wear resisting property in addition.Mn content is comparatively suitable in 1.5～2.5% scopes.
The Main Function of Co is the solubleness that reduces C, promotes Carbide Precipitation.Co can also increase the dislocation desity of matrix, prevents that dislocation from replying in tempering, therefore improves intensity.But Co price, its add-on are comparatively suitable in 2～5% scopes.
Simultaneously, in order to obtain good combination of strength and toughness, must strictly control impurity content, its S and P all are no more than 20ppm lower than 0.005%, O and N.
Steel of the present invention adopts vacuum induction furnace smelting.After melting, the steel ingot processing that should homogenize under 1200 ° of C, carry out hot-work subsequently in 1160 ~ 850 ° of C scopes, and after hot-work, softening processing the under 680 ° of C, discharge internal stress.Final heat treating regime is 940 ~ 960 ° of C solution treatment, then carries out tempering in 200 ~ 350 ° of C scopes.
According to above-mentioned chemical composition and the prepared steel of the present invention of production method, not only have higher tensile strength and fracture toughness property, but also have lower yield tensile ratio, and good dynamic properties.Specific performance is: tensile strength R
m〉=1950MPa, R
P0..2〉=1540MPa, K
1c〉=80MPam, R
P0..2/
R
m≤ 0.83.
Compared with prior art, the present invention not only intensity is high, and fracture toughness property is good, and yield tensile ratio is low, and economical effectiveness is better.
Embodiment
According to the chemical composition scope of design, smelt 4 stove steel of the present invention on the 25kg vacuum induction furnace, their chemical composition and mechanical property are as shown in table 2 and table 3.Wherein, table 2 is the Chemical Composition (wt.%) of the embodiment of the present invention, and table 3 is the mechanical property of the embodiment of the present invention.
The chemical composition of table 2 embodiment (wt.%)
Continued 2
The mechanical property of table 3 embodiment
Steel ingot of the present invention through 1200 ° of C, homogenized in 6 hours process after, be cooled at 1160 ° of C and come out of the stove, One-time forging is to 35mm * 35mm square rod, forge rod cooling in air after, put into stove and anneal at once, annealing schedule is 680 ° of C, 8 hours, then air cooling.Cut the blank of mechanical property sample after annealing from square rod.The sample blank is through after roughing, and oil cooling after 950 ° of C are incubated 1 hour is afterwards at 2 hours air coolings of 250 ° of C insulations.All samples are refined to final size again after low-temperaturetempering.All samples carry out Mechanics Performance Testing in room temperature, and result is as shown in table 3.
Contrast table 3 and table 1 as can be known, the present invention compares with low-temperaturetempering ultrahigh-strength steel 4340,300M, PremoMet and D6AC, tensile strength and yield tensile ratio are suitable, and plane fracture toughness is higher; G50 compares with the low-temperaturetempering ultrahigh-strength steel, and plane fracture toughness is lower, but intensity is higher; 30CrMnSiN2A compares with the low-temperaturetempering ultrahigh-strength steel, and plane fracture toughness is suitable, and intensity obviously improves.Steel of the present invention is compared with the high tempering ultrahigh-strength steel in table 1, and the consumption of the noble elements such as Co and Ni significantly reduces, and yield tensile ratio significantly reduces.This shows, steel of the present invention has better cost performance, and more excellent comprehensive mechanical property has the prospect of promoting the use of.
Claims (1)
1. a low-temperaturetempering martensite ultrahigh-strength steel, is characterized in that, chemical component weight percentage ratio is: C: 0.35-0.45%, Ni:3-6%, Co:2-5%, Si:1.5-2.5%, Mn:1.5-2.5%, Cr:0.5-1.25%, Mo:0.5-2.0%, Nb:0.01-0.05%, Ti:0.01-0.03% requires: S≤0.005% simultaneously, P≤0.005%, O≤20ppm, N≤20ppm, all the other are Fe.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110036128A (en) * | 2016-12-05 | 2019-07-19 | 日本制铁株式会社 | High-strength steel sheet |
| CN112143960A (en) * | 2019-06-28 | 2020-12-29 | 宝山钢铁股份有限公司 | Steel plate with ultrahigh strength and low yield ratio and manufacturing method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1075172A (en) * | 1993-01-13 | 1993-08-11 | 冶金工业部钢铁研究总院 | High-strength and high-toughness steel |
| JP2000017388A (en) * | 1998-04-30 | 2000-01-18 | Sumitomo Electric Ind Ltd | Oil tempered steel wire for spring |
| CN101270453A (en) * | 2008-05-21 | 2008-09-24 | 钢铁研究总院 | Ultrahigh-strength thermal forming martensitic steel |
| CN102212760A (en) * | 2011-06-10 | 2011-10-12 | 钢铁研究总院 | Steel with high toughness and ultrahigh strength |
-
2013
- 2013-03-20 CN CN2013100906488A patent/CN103147020A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1075172A (en) * | 1993-01-13 | 1993-08-11 | 冶金工业部钢铁研究总院 | High-strength and high-toughness steel |
| JP2000017388A (en) * | 1998-04-30 | 2000-01-18 | Sumitomo Electric Ind Ltd | Oil tempered steel wire for spring |
| CN101270453A (en) * | 2008-05-21 | 2008-09-24 | 钢铁研究总院 | Ultrahigh-strength thermal forming martensitic steel |
| CN102212760A (en) * | 2011-06-10 | 2011-10-12 | 钢铁研究总院 | Steel with high toughness and ultrahigh strength |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110036128A (en) * | 2016-12-05 | 2019-07-19 | 日本制铁株式会社 | High-strength steel sheet |
| CN112143960A (en) * | 2019-06-28 | 2020-12-29 | 宝山钢铁股份有限公司 | Steel plate with ultrahigh strength and low yield ratio and manufacturing method thereof |
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Application publication date: 20130612 |