CN100363513C - Heat treatment process for large microalloyed medium carbon steel engine crankshaft - Google Patents
Heat treatment process for large microalloyed medium carbon steel engine crankshaft Download PDFInfo
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- CN100363513C CN100363513C CNB2005100469049A CN200510046904A CN100363513C CN 100363513 C CN100363513 C CN 100363513C CN B2005100469049 A CNB2005100469049 A CN B2005100469049A CN 200510046904 A CN200510046904 A CN 200510046904A CN 100363513 C CN100363513 C CN 100363513C
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Abstract
The present invention is heat treatment process for large engine crankshaft of microalloyed medium carbon steel. The heat treatment process has the forging afterheat utilized, increased normalizing treatment at 860-900 deg.c for 110-180 min, and subsequent fast cooling at 40-60 deg.c/min, slow cooling to 300 deg.c, discharging and stress ageing treatment. The present invention performs secondary phase change treatment of crankshaft after forging through normalizing with the forging afterheat and the controlled cooling, and can improve the metallurgical structure after forging, fine metallurgical structure crystal grain, raise plasticity and toughness and obtain ideal comprehensive mechanical performance.
Description
Technical field
What the present invention relates to is the heat treating method Technology of large microalloyed medium carbon steel engine crankshaft forging.
Background technology
Domestic non-hardened and tempered steel bent axle is because plasticity and toughness properties are relatively poor, its major part can only be applied on the parts such as the connecting rod, bent axle of light truck and car, and application being arranged at the comings B that also has only DongFeng Automobile Co., Ltd aspect the big-block engine bent axle, C Series Crankshaft product, the thermal treatment of controlled chilling method was made after this bent axle product adopted and forges.Its processing method is also only controlled intensity and hardness number, its intensity is σ b 〉=800Mpa, hardness is HB235-280, other technical indicator can't be controlled especially, its unit elongation is δ 5 〉=10-13%, grain fineness number is 0 grade individually, and majority is lower than 3 grades, and this and the desired σ b 〉=800Mpa of the user of producer, σ s 〉=500Mpa, δ 5 〉=16%, ψ 〉=35%, hardness are that HB241-295, grain fineness number are narrower than 5 grades technical requirement and differ greatly.
As the bent axle steel, its most basic condition is to reach desirable strength and toughness reguirements.And existing non-hardened and tempered steel bent axle heat treating method exists crystal grain thick, the technology disadvantage of plasticity and poor toughness.Analyze after deliberation and find that forging and final forging temperature height, speed of cooling are to cause the major cause of above-mentioned technology disadvantage slowly.Forging the back air cooling handles, its metallographic structure is the mixed structure that waits axle ferrite and lamellar pearlite of separating out along austenite grain boundary, raising with the Forge Heating temperature, austenite crystal is grown up, just analysing ferrite content behind the air cooling reduces, perlite effect size increases, and in the Heating temperature more than 1200 ℃, this variation is particularly remarkable.The increase of perlite relative quantity is the major cause that hardness increases, and the toughness main reasons for decrease is the thick and ferrite relative quantity minimizing of crystal grain.If forging temperature is controlled at below 1200 ℃, for the big-block engine bent axle, it is complex-shaped, has not only increased the difficulty of forging molding, and also sharply descends die life, and it is very difficult to cut edge, and causing can't ordinary production.
Summary of the invention
The goal of the invention of patent application of the present invention is to provide a kind of heat treatment process for large microalloyed medium carbon steel engine crankshaft, the non-hardened and tempered steel bent axle that this thermal treatment process of process is handled is except that meeting intensity and hardness technical indicator, also to reach refinement metallographic structure crystal grain, improve the requirement of the moulding of non-hardened and tempered steel, toughness index simultaneously, make it be suitable for using as the big-block engine bent axle.The heat treatment process for large microalloyed medium carbon steel engine crankshaft of patent of the present invention, the major technique content of its technical scheme is: will forge back bent axle controlled chilling to 500-700 ℃ of temperature, carrying out normalizing treatment is heated to 860-900 ℃ of temperature and is incubated 110-180 minute, with 40-60 ℃/minute speed of cooling make its temperature reduce to 500-700 ℃ thereafter, be cooled to 300 ℃ with the speed of cooling that is no more than 15 ℃/minute then and come out of the stove, enter the stress ageging treatment process.
Heat treatment process for large microalloyed medium carbon steel engine crankshaft technical scheme of the present invention, utilize forging back waste heat to carry out normalizing and controlled chilling again, implement the second-order phase transition processing to forging the back bent axle, improve and forge the back metallographic structure, control ferrite and pearlitic relative content, refinement metallographic structure crystal grain, improve its plasticity and toughness index, and can obtain comparatively ideal comprehensive mechanical performance, fully satisfied the demand of user to product.
Embodiment
Below will elaborate to technical scheme of the present invention.
The heat-treatment technology method of the large microalloyed medium carbon steel engine crankshaft of patent application of the present invention, its operational path is: controlled chilling → alignment and destressing ageing treatment after forging → forging back controlled chilling → normalizing → normalizing.In the present embodiment, be that example describes with S38MnSiV and two kinds of materials of 48MnV.Its forging temperature should be at 1200 ℃ more than-1240 ℃, hang behind the finish-forging to enter and forge controlled chilling chamber, back controlled chilling, its speed of cooling is about 25 ℃-30 ℃/minute, it is cooled to 500-700 ℃ of temperature range, reenter the normalizing furnace normalizing treatment and be heated to 860-900 ℃, be incubated 110-180 minute and carry out the second-order phase transition processing, hang again after the normalizing treatment to enter and forge controlled chilling chamber, back, force cooling in the pneumatics mode, after with speed of cooling 40-60 ℃/minute bent axle being cooled to 500-700 ℃, be cooled to about 300 ℃ of air coolings of coming out of the stove with speed of cooling relatively slowly again, its speed of cooling preferably is no more than 15 ℃/minute, enters destressing ageing treatment process process thereafter.
Its hardness contrast form is before and after the destressing timeliness:
| Number of times | Technology | Hardness (HB) | |||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||
| 1 | Timeliness not after the normalizing | 240 | 237 | 242 | 250 | 241 | 255 | 248 | 256 | 242 | 235 |
| Timeliness | 255 | 245 | 266 | 262 | 253 | 260 | 248 | 248 | 250 | 258 | |
| 2 | Timeliness not after the normalizing | 245 | 246 | 255 | 244 | 235 | 257 | 255 | 246 | 237 | 242 |
| Timeliness | 257 | 260 | 248 | 250 | 246 | 252 | 257 | 253 | 250 | 246 | |
Through 540～560 ℃ of ageing treatment, promote separating out of matrix strengthening compounds such as V, N.Hardness number does not reduce substantially, and ascendant trend is slightly arranged on the contrary.
The contrast situation of each mechanical behavior value of three kinds of methods of waste heat normalizing controlled chilling thermal treatment process after direct controlled chilling thermal treatment process, the forging common normalizing heat treatment technique in back and the forging after below will relatively forging by form.
| Material | State | σb (N/mm 2) | σs (N/mm 2) | δ 5 (％) | ψ (％) | ak (J/ Cm 2) | Hardness (HB) | Grain fineness number |
| S38M nSiV | Forge directly controlled chilling of back | 851～ 921 | 554～ 618 | 10～ 14 | 22 ～ 34 | 14～ 21 | 249～ 262 | 3～ 4.5 |
| 48Mn V | 908～ 933 | 594～ 617 | 9～ 12 | 12 ～ 23 | 8～ 26 | 256～ 271 | 3～ 4.5 | |
| S38M nSiV | Common normalizing treatment | 755～ 848 | 490～ 586 | 18～ 25 | 29 ～ 58 | 37～ 115 | 232～ 254 | 6.5～ 7 |
| 48Mn V | 730～ 864 | 478～ 489 | 18～ 19 | 51 ～ 55 | 11～ 50 | 255 | 6～ 6.5 | |
| S38M nSiV | Waste heat normalizing controlled chilling | 813～ 916 | 506～ 633 | 16～ 21 | 39 ～ 55 | 33～ 80 | 235～ 302 | 7～ 8.5 |
| 48Mn V | 776～ 860 | 490～ 560 | 16～ 19 | 35 ～ 55 | 29～ 66 | 235～ 290 | 7～ 8.5 |
Through contrast as can be known, the crankshaft strength of S38MnSiV material and plasticity and toughness and stability all are better than the 48MnV crankshaft material on the one hand, show on the other hand: first kind of processing method, its metallographic structure crystal grain is thick, just analyse ferrite content and reduce, perlite effect size increases, and hardness, intensity index are all higher, but plasticity and toughness are lower, far do not reach customer need; Second kind of processing method, its metallographic structure crystal grain is tiny, and it is more just to analyse ferrite content, and perlite effect size is less, and its plasticity and toughness are too high, but hardness, intensity index are all lower, do not reach customer need; The third processing method, i.e. present patent application processing method, its metallographic structure crystal grain is tiny, because its speed of cooling is fast, it is moderate just to analyse ferrite, perlite effect moderate dimensions, hardness number is higher, and its comprehensive mechanical performance is relatively good, finishes and has satisfied customer need.
Claims (1)
1. heat treatment process for large microalloyed medium carbon steel engine crankshaft, it is characterized in that its method is: will forge back bent axle controlled chilling to 500-700 ℃ of temperature, carrying out normalizing treatment is heated to 860-900 ℃ of temperature and is incubated 110-180 minute, with 40-60 ℃/minute speed of cooling make its temperature reduce to 500-700 ℃ thereafter, reduce to 300 ℃ with the speed of cooling that is no more than 15 ℃/minute then and come out of the stove, enter the stress ageging treatment process.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2005100469049A CN100363513C (en) | 2005-07-19 | 2005-07-19 | Heat treatment process for large microalloyed medium carbon steel engine crankshaft |
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| CNB2005100469049A CN100363513C (en) | 2005-07-19 | 2005-07-19 | Heat treatment process for large microalloyed medium carbon steel engine crankshaft |
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| CN1900328A CN1900328A (en) | 2007-01-24 |
| CN100363513C true CN100363513C (en) | 2008-01-23 |
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| CNB2005100469049A Expired - Fee Related CN100363513C (en) | 2005-07-19 | 2005-07-19 | Heat treatment process for large microalloyed medium carbon steel engine crankshaft |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102728772A (en) * | 2012-06-26 | 2012-10-17 | 江苏金源锻造股份有限公司 | Method for forging large ship crank shaft |
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| CN102329943B (en) * | 2010-07-12 | 2013-07-17 | 中国有色（沈阳）冶金机械有限公司 | Thermal treatment method for large electroslag smelting cast 42CrMo steel crankshaft |
| CN101921947B (en) * | 2010-08-12 | 2011-11-09 | 荆州环宇汽车零部件有限公司 | Nodular cast iron crankshaft waste heat air cooling and normalizing method |
| CN101921904B (en) * | 2010-08-12 | 2011-11-09 | 荆州环宇汽车零部件有限公司 | Spheroidal graphite cast iron crankshaft normalizing method without normalizing consumption |
| CN101921903B (en) * | 2010-08-12 | 2012-07-04 | 荆州环宇汽车零部件有限公司 | Method for obtaining high-pearlite high-tenacity nodular cast iron crankshaft |
| CN102728754A (en) * | 2011-04-07 | 2012-10-17 | 江铃汽车股份有限公司 | Reinforced control cooling method for non-tempered steel forging |
| CN103131825A (en) * | 2011-12-02 | 2013-06-05 | 天津市三焱电渣钢有限公司 | Quick heating quenching technique for electroslag smelting casting large section crankshaft |
| CN102605147A (en) * | 2012-03-30 | 2012-07-25 | 江苏凌飞锻造有限公司 | Method for carrying out normalizing heat treatment by using waste heat from forging of forged piece |
| CN104946873A (en) * | 2015-06-18 | 2015-09-30 | 秦皇岛开发区春光铸造机械有限公司 | After-forged heat treatment technology of LZ50 steel axle |
| CN107475501B (en) * | 2016-06-07 | 2019-02-12 | 江苏恒力制动器制造有限公司 | A kind of Micro Alloying brake camshaft and its manufacturing method |
| CN106987690A (en) * | 2017-05-19 | 2017-07-28 | 成都亨通兆业精密机械有限公司 | A kind of manufacturing process of forged steel crankshaft |
| CN110935838B (en) * | 2019-12-25 | 2021-05-04 | 常州常超模具有限公司 | Roller processing method suitable for improving forging penetration and shortening heat treatment period |
| CN113174470B (en) * | 2021-04-15 | 2022-03-08 | 山东钢铁股份有限公司 | F45MnVS steel continuous normalizing heat treatment method |
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| JP2002294340A (en) * | 2001-03-30 | 2002-10-09 | Honda Motor Co Ltd | Heat treatment method, heat treatment apparatus, and pallet used for heat treatment |
| CN1540004A (en) * | 2003-11-03 | 2004-10-27 | 中国重型汽车集团有限公司 | Therma processing method for crankshaft of high-power engine |
| KR20050027690A (en) * | 2003-09-16 | 2005-03-21 | 현대자동차주식회사 | A temperature control system in self tempering process of crank shaft and control method thereof |
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2005
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002294340A (en) * | 2001-03-30 | 2002-10-09 | Honda Motor Co Ltd | Heat treatment method, heat treatment apparatus, and pallet used for heat treatment |
| KR20050027690A (en) * | 2003-09-16 | 2005-03-21 | 현대자동차주식회사 | A temperature control system in self tempering process of crank shaft and control method thereof |
| CN1540004A (en) * | 2003-11-03 | 2004-10-27 | 中国重型汽车集团有限公司 | Therma processing method for crankshaft of high-power engine |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102728772A (en) * | 2012-06-26 | 2012-10-17 | 江苏金源锻造股份有限公司 | Method for forging large ship crank shaft |
| CN102728772B (en) * | 2012-06-26 | 2015-11-11 | 江苏金源锻造股份有限公司 | A kind of forging method of crankshaft used for large boat |
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| CN1900328A (en) | 2007-01-24 |
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Owner name: NO.518 INSTERNAL COMBUSTION ENGINE PARTS CO., LTD Free format text: FORMER OWNER: NO.518 INSTERNAL COMBUSTION ENGINE PARTS CO., LTD., LIAONING Effective date: 20070406 |
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Effective date of registration: 20070406 Address after: 118009 No. 97, North Ring Road, Liaoning, Dandong Applicant after: Liaoning 518 Internal-Combustion Engine Fittings Co., Ltd. Co-applicant after: Shanghai Diesel Engine Co., Ltd. Address before: 118009 No. 97, North Ring Road, Liaoning, Dandong Applicant before: Liaoning 518 Internal-Combustion Engine Fittings Co., Ltd. |
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