CN104805451A - Heat processing technology for improving impact energy of 20CrNiMo alloy steel - Google Patents
Heat processing technology for improving impact energy of 20CrNiMo alloy steel Download PDFInfo
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- CN104805451A CN104805451A CN201510148395.4A CN201510148395A CN104805451A CN 104805451 A CN104805451 A CN 104805451A CN 201510148395 A CN201510148395 A CN 201510148395A CN 104805451 A CN104805451 A CN 104805451A
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Abstract
The invention provides a heat processing technology for improving the impact energy of 20CrNiMo alloy steel. The technology includes the following steps: I, performing carburizing treatment to the 20CrNiMo alloy steel until the depth of a carburizing layer reaches 1.4 mm to 1.7 mm; II, performing primary quenching; III, performing primary tempering, V, performing secondary quenching; IV, performing secondary tempering. According to the invention, through improving the heat processing technology of the 20CrNiMo alloy steel, the problem that other excellent performances of the 20CrNiMo alloy steel cannot be fully exerted due to lower impact energy is solved, the material usability is better, and the application range is wider.
Description
Technical field
The invention belongs to mechanical material technical field of heat treatment, be specifically related to a kind of thermal treatment process improving 20CrNiMo steel alloy ballistic work.
Background technology
20CrNiMo steel alloy is the trade mark of a kind of structural alloy steel that CNS " GB/T 3077-1999 " specifies, unified digital code: A50202.
Point out in GB, the thermal treatment process of 20CrNiMo steel alloy is specific as follows: forging temperature 1177 DEG C ~ 1232 DEG C; Normalizing temperature: 899 DEG C ~ 954 DEG C; Hardness: 187HBW; Carburizing temperature: 899 DEG C ~ 927 DEG C; Quenching temperature: 850 DEG C, refrigerant: oil; Tempering temperature: 200 DEG C, refrigerant: air.The mechanical property obtained is as follows: Impact energy Ak v:>=47J; Notched bar impact strength α kv:>=59J/cm
2.
Because the hardening capacity of 20CrNiMo steel alloy is higher, without temper brittleness, weldability is fairly good, forms the tendency of cold cracking very little, machinability and cold strain plasticity good.Generally use under modified or carburizing and quenching state, be usually used in manufacturing the gear in small and medium-sized car, the engine of tractor and transmission system, as the gear turn over sub-IC engine link rod porthole cross section forging of steam turbine.Also carburizing part, cyaniding part that 12CrNi3 steel making requirement heart portion performance is higher can be replaced, as tooth pawl and the cone body of the tooth-wheel bit of oil drilling and metallurgical surface mines.
Through making thorough investigation and study to Mechanical Industry of China for a long time, following the tracks of, and the research learning to all kinds of national standard, specification handbook, find that the thermal treatment process generally adopted at present is: 930 DEG C of carburizings, case depth 1.8mm ~ 2.2mm, 860 DEG C of oil quenchings, 200 DEG C of tempering.But find in the production and application process of reality, when 20CrNiMo steel alloy after carburizing and quenching process uses as important spare part, but often there is phenomenon of rupture because its center toughness is poor, Impact energy Ak u is lower, usually about 60J is only had, have a strong impact on product to use, and very ill effect is caused to market.
Owing to containing a small amount of Mo element in 20CrNiMo alloy steel material, improve the anti-tempered performance of material; Again because Mn content is higher, making the top of austenite isothermal transformation diagram toward moving to right, making supercooled austenite more stable, thus making its hardening capacity fine; Especially under the condition of equal tensile strength and yield strength, the carbon equivalent Cev of this material only has 0.6, has good welding property, is that other steel capital cannot be when, and under the prerequisite obtaining equal mechanical property and welding property, the economic performance of this material is also very excellent.The overall evaluation, 20CrNiMo steel alloy over-all properties is better, and ballistic work is lower only.
Therefore, need a kind of thermal treatment process improving 20CrNiMo steel alloy ballistic work of research and development badly, make 20CrNiMo steel alloy obtain good ballistic work, finally make the overall mechanical properties of alloy steel material greatly improve, play better applicable performance, have use range widely.
Summary of the invention
Technical problem to be solved by this invention is for above-mentioned the deficiencies in the prior art, provides a kind of thermal treatment process improving 20CrNiMo steel alloy ballistic work.The present invention, by improving the thermal treatment process of 20CrNiMo steel alloy, solves the problem causing other superperformances of 20CrNiMo steel alloy to play one's part to the full because ballistic work is lower, and make the applicable performance of this material better, use range is wider.
For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of thermal treatment process improving 20CrNiMo steel alloy ballistic work, is characterized in that, this technique comprises the following steps:
Step one, carburizing: be carry out carburizing treatment, till case depth is 1.4mm ~ 1.7mm under the condition of 930 DEG C in temperature by 20CrNiMo steel alloy;
Step 2, primary quenching: the 20CrNiMo steel alloy after carburizing in step one is cooled to 870 DEG C ~ 890 DEG C are oil quenching after being incubated 2.5h under the condition of 0.8% ~ 0.9% at carbon potential;
Step 3, a tempering: the 20CrNiMo steel alloy after primary quenching in step 2 is warming up to 590 DEG C ~ 610 DEG C, air cooling after insulation 3h;
Step 4, secondary quenching: the 20CrNiMo steel alloy after a tempering in step 3 is warming up to 830 DEG C ~ 850 DEG C are oil quenching after being incubated 3h under the condition of 0.8% ~ 0.9% at carbon potential;
Step 5, double tempering: the 20CrNiMo steel alloy after secondary quenching in step 4 is warming up to 190 DEG C ~ 210 DEG C, air cooling after insulation 4h.
Above-mentioned a kind of thermal treatment process improving 20CrNiMo steel alloy ballistic work, is characterized in that, the steel alloy of 20CrNiMo described in step one is the steel alloy after esr process.
The present invention compared with prior art has the following advantages:
1, the present invention is under the principle not affecting other mechanical properties of 20CrNiMo steel alloy completely, now through carrying out careful analysis to the links of prior heat treatment, repeatedly prove, test, by changing metallographic structure under differing temps, time, media environment, then the sample of the different states obtained is tested, contrasts, optimized, make it can obtain good structure property in each link heat treated, thus obtain finally good performance.
2, the present invention is by improving the thermal treatment process of 20CrNiMo, thus obtain good ballistic work, the overall mechanical properties of 20CrNiMo is finally made greatly to improve, make the applicable performance of this material better, use range is wider, this is the breakthrough reform in low-carbon alloy steel thermal treatment process technology aspect, and an important milestone of Ye Shi China material science and technology aspect, compensate for the gap for a long time with developed country in material heat treatment.The present invention is under the prerequisite meeting hardening capacity, tensile strength, yield strength, shock resistance and good welding property, and this material advantage in economic benefit is very large, and the economic results in society brought are huge.The present invention is through finding the analysis of each heat treatment link:
(1) esr low-carbon micro steel-alloy principle of strengthening and toughening: the harmful element content such as sulphur, phosphorus being reduced steel by esr, improve purity, in former performance basis, add microalloy element simultaneously, form tiny infusible compound, pinning effect is played to crystal boundary, thus crystal grain thinning, reach the object of highly malleablized process.
(2) the present invention is through twice quenching, and tissue attenuates, and this is because original austenite grain is by refinement, because material is when heating quenching, the nucleation sites of crystal grain is mainly at crystal boundary, and crystal grain is more tiny, and crystal boundary is more, namely nucleation site is more, again because secondary quenching temperature is lower, grain growth is comparatively slow, after quenching, the actual die of material is more tiny, is conducive to the intensity and the impelling strength that improve material.
(3) the Qa temperature of the present invention is lower, and under identical soaking time, make materials microstructure be martensite and ferrite, soft or hard two-phase exists simultaneously, is conducive to the raising of material impact toughness.
(4) the present invention carries out twice quenching to 20CrNiMo, the carbide rank of material can be reduced, because carbide is brittlement phase, carbide portion can be made during secondary quenching to dissolve, and spread outside intracrystalline, depths, top layer and surface, make the distribution of carbon be tending towards even, The method avoids material is reduce carbide rank and the oxidation and decarbonization that produces of normalizing and distortion again, thus improves the toughness of material.Crystal grain thinning, exceeds 3 ~ 4 grades than originally, reach 12 grades.
(5) the present invention is found by research, cementation zone is darker, impelling strength is lower, because cementation zone itself belongs to brittlement phase, therefore, case depth innovation is 1.4mm ~ 1.7mm (conventional depth is 1.8mm ~ 2.2mm) by the present invention, thus the toughness of 20CrNiMo alloy steel material is significantly improved.
In sum, the present invention is by carrying out esr Metallurgical processing again to the 20CrNiMo low-carbon alloy steel in existing GB, again through twice quenching, finally make the crystal grain refinement more of 20CrNiMo steel alloy, organize more even, performance is more stable, overall mechanical properties improves greatly, make the applicable performance of this material better, use range is wider, economic performance is also very remarkable, this is the breakthrough reform in low-carbon alloy steel thermal treatment process technology aspect, in the machinery industry of our country, esr and secondary quenching technology is adopted also to be beyond example to 20CrNiMo, this will be an important milestone of China's material science and technology aspect, compensate for the gap for a long time with developed country in material heat treatment.
Below in conjunction with drawings and Examples, the present invention is described in further detail.
Accompanying drawing explanation
Fig. 1 is the microstructure figure of the 20CrNiMo steel alloy after the embodiment of the present invention 1 thermal treatment.
Fig. 2 is the microstructure figure of the 20CrNiMo steel alloy after comparative example 1 thermal treatment.
Fig. 3 is the core organization chart of the 20CrNiMo steel alloy after the embodiment of the present invention 1 thermal treatment.
Fig. 4 is the core organization chart of the 20CrNiMo steel alloy after comparative example 1 thermal treatment.
Fig. 5 is the metallographic structure grain fineness number figure of the 20CrNiMo steel alloy after the embodiment of the present invention 1 thermal treatment.
Fig. 6 is the metallographic structure grain fineness number figure of the 20CrNiMo steel alloy after comparative example 1 thermal treatment.
Embodiment
Embodiment 1
The thermal treatment process that the present embodiment improves 20CrNiMo steel alloy ballistic work comprises the following steps:
Step one, carburizing: be carry out carburizing treatment, till case depth is 1.5mm under the condition of 930 DEG C in temperature by the 20CrNiMo steel alloy after esr process;
Step 2, primary quenching: the 20CrNiMo steel alloy after carburizing in step one is cooled to 880 DEG C are oil quenching after being incubated 2.5h under the condition of 0.85% at carbon potential;
Step 3, a tempering: the 20CrNiMo steel alloy after primary quenching in step 2 is warming up to 600 DEG C, air cooling after insulation 3h;
Step 4, secondary quenching: the 20CrNiMo steel alloy after a tempering in step 3 is warming up to 840 DEG C are oil quenching after being incubated 3h under the condition of 0.85% at carbon potential;
Step 5, double tempering: the 20CrNiMo steel alloy after secondary quenching in step 4 is warming up to 200 DEG C, air cooling after insulation 4h.
Embodiment 2
The thermal treatment process that the present embodiment improves 20CrNiMo steel alloy ballistic work comprises the following steps:
Step one, carburizing: be carry out carburizing treatment, till case depth is 1.7mm under the condition of 930 DEG C in temperature by the 20CrNiMo steel alloy after esr process;
Step 2, primary quenching: the 20CrNiMo steel alloy after carburizing in step one is cooled to 890 DEG C are oil quenching after being incubated 2.5h under the condition of 0.9% at carbon potential;
Step 3, a tempering: the 20CrNiMo steel alloy after primary quenching in step 2 is warming up to 610 DEG C, air cooling after insulation 3h;
Step 4, secondary quenching: the 20CrNiMo steel alloy after a tempering in step 3 is warming up to 850 DEG C are oil quenching after being incubated 3h under the condition of 0.9% at carbon potential;
Step 5, double tempering: the 20CrNiMo steel alloy after secondary quenching in step 4 is warming up to 210 DEG C, air cooling after insulation 4h.
Embodiment 3
The thermal treatment process that the present embodiment improves 20CrNiMo steel alloy ballistic work comprises the following steps:
Step one, carburizing: be carry out carburizing treatment, till case depth is 1.4mm under the condition of 930 DEG C in temperature by the 20CrNiMo steel alloy after esr process;
Step 2, primary quenching: the 20CrNiMo steel alloy after carburizing in step one is cooled to 870 DEG C are oil quenching after being incubated 2.5h under the condition of 0.8% at carbon potential;
Step 3, a tempering: the 20CrNiMo steel alloy after primary quenching in step 2 is warming up to 590 DEG C, air cooling after insulation 3h;
Step 4, secondary quenching: the 20CrNiMo steel alloy after a tempering in step 3 is warming up to 830 are oil quenching after being incubated 3h under the condition of 0.8% at carbon potential;
Step 5, double tempering: the 20CrNiMo steel alloy after secondary quenching in step 4 is warming up to 190 DEG C, air cooling after insulation 4h.
Comparative example 1
This comparative example adopts traditional thermal treatment process to 20CrNiMo steel alloy, concrete treating processes is: by 20CrNiMo steel alloy in 930 DEG C of carburizings, till case depth is 1.8mm ~ 2.2mm, be then cooled to 860 DEG C of oil quenchings, be warming up to 200 DEG C afterwards and carry out tempering.
For checking, the present invention can solve by improving thermal treatment process the problem causing other superperformances of 20CrNiMo to play one's part to the full because ballistic work is lower, make the applicable performance of this material better, use range is wider, therefore, in strict accordance with national standard " GJB150.18-86 " " military equipment environment method-shock test " and " GB/T229-2007 " " metallic substance Charpy pendulum impact test method ", the 20CrNiMo steel alloy after the embodiment of the present invention 1 and comparative example 1 process is tested.The concrete comparative analysis of test-results is as follows:
The quenching structure of the surface cementation layer that the 20CrNiMo steel alloy after comparative example 1 processes obtains is that needle type martensite adds angle massive carbide and a small amount of residual austenite (as shown in Figure 2), heart portion is lath martensite, grain fineness number is 8.5 grades (as shown in Figure 6), and the ballistic work in heart portion is about 60J (as shown in Figure 4).
The tiny needle type martensite of quenching structure of the surface cementation layer that the 20CrNiMo steel alloy after embodiment 1 processes obtains adds a small amount of residual austenite (as shown in Figure 1), heart portion is that tiny lath martensite adds a small amount of ferrite, grain fineness number is 12 grades (as shown in Figure 5), the ballistic work in heart portion remains on more than 175J (as shown in Figure 3) through stable testing repeatedly, is nearly 3 times of the ballistic work that traditional technology obtains.
In addition, learn after testing, the over-all properties such as hardening capacity, tensile strength, yield strength, welding property of the 20CrNiMo steel alloy after embodiment 1 processes compares ratio 1 and noticeable change does not occur.
As seen from the above comparison, the present invention is by improving the thermal treatment process of 20CrNiMo, thus obtain good ballistic work, the overall mechanical properties of 20CrNiMo is finally made greatly to improve, make the applicable performance of this material better, use range is wider, and this is the breakthrough reform in low-carbon alloy steel thermal treatment process technology aspect, an important milestone of Ye Shi China material science and technology aspect, compensate for the gap for a long time with developed country in material heat treatment.
The above is only preferred embodiment of the present invention, not imposes any restrictions the present invention.Every above embodiment is done according to invention technical spirit any simple modification, change and equivalence change, all still belong in the protection domain of technical solution of the present invention.
Claims (2)
1. improve a thermal treatment process for 20CrNiMo steel alloy ballistic work, it is characterized in that, this technique comprises the following steps:
Step one, carburizing: be carry out carburizing treatment, till case depth is 1.4mm ~ 1.7mm under the condition of 930 DEG C in temperature by 20CrNiMo steel alloy;
Step 2, primary quenching: the 20CrNiMo steel alloy after carburizing in step one is cooled to 870 DEG C ~ 890 DEG C are oil quenching after being incubated 2.5h under the condition of 0.8% ~ 0.9% at carbon potential;
Step 3, a tempering: the 20CrNiMo steel alloy after primary quenching in step 2 is warming up to 590 DEG C ~ 610 DEG C, air cooling after insulation 3h;
Step 4, secondary quenching: the 20CrNiMo steel alloy after a tempering in step 3 is warming up to 830 DEG C ~ 850 DEG C are oil quenching after being incubated 3h under the condition of 0.8% ~ 0.9% at carbon potential;
Step 5, double tempering: the 20CrNiMo steel alloy after secondary quenching in step 4 is warming up to 190 DEG C ~ 210 DEG C, air cooling after insulation 4h.
2. a kind of thermal treatment process improving 20CrNiMo steel alloy ballistic work according to claim 1, is characterized in that, the steel alloy of 20CrNiMo described in step one is the steel alloy after esr process.
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Cited By (5)
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| CN106048149A (en) * | 2016-07-16 | 2016-10-26 | 柳州科尔特锻造机械有限公司 | Heat treatment process of low-alloy steel |
| CN107385156A (en) * | 2017-06-29 | 2017-11-24 | 江南工业集团有限公司 | The Strengthening and Toughening composite heat treating method of 30CrMnSiA steel |
| CN112760457A (en) * | 2019-10-21 | 2021-05-07 | 中国科学院金属研究所 | Heat treatment method for improving laser melting deposition 12CrNi2 alloy steel product of strength and elongation |
| CN113249552A (en) * | 2021-05-26 | 2021-08-13 | 河南中原特钢装备制造有限公司 | Quenching and tempering heat treatment process for improving flaw detection clutter of 2Cr13 rotor |
| CN114481007A (en) * | 2022-01-22 | 2022-05-13 | 成都天马精密机械有限公司 | Heat treatment process for carburizing bearing steel |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106048149A (en) * | 2016-07-16 | 2016-10-26 | 柳州科尔特锻造机械有限公司 | Heat treatment process of low-alloy steel |
| CN107385156A (en) * | 2017-06-29 | 2017-11-24 | 江南工业集团有限公司 | The Strengthening and Toughening composite heat treating method of 30CrMnSiA steel |
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| CN112760457B (en) * | 2019-10-21 | 2022-05-31 | 中国科学院金属研究所 | Heat treatment method for improving laser melting deposition 12CrNi2 alloy steel product of strength and elongation |
| CN113249552A (en) * | 2021-05-26 | 2021-08-13 | 河南中原特钢装备制造有限公司 | Quenching and tempering heat treatment process for improving flaw detection clutter of 2Cr13 rotor |
| CN113249552B (en) * | 2021-05-26 | 2023-03-31 | 河南中原特钢装备制造有限公司 | Quenching and tempering heat treatment process for improving flaw detection clutter of 2Cr13 rotor |
| CN114481007A (en) * | 2022-01-22 | 2022-05-13 | 成都天马精密机械有限公司 | Heat treatment process for carburizing bearing steel |
| CN114481007B (en) * | 2022-01-22 | 2024-05-10 | 成都天马精密机械有限公司 | Carburizing bearing steel heat treatment process |
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Application publication date: 20150729 |