CN104694872A - Gas nitriding method for 55 SiCr steel bearing spring - Google Patents
Gas nitriding method for 55 SiCr steel bearing spring Download PDFInfo
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- CN104694872A CN104694872A CN201310654829.9A CN201310654829A CN104694872A CN 104694872 A CN104694872 A CN 104694872A CN 201310654829 A CN201310654829 A CN 201310654829A CN 104694872 A CN104694872 A CN 104694872A
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Abstract
The invention discloses a gas nitriding method for a 55 SiCr steel bearing spring. The gas nitriding method comprises the following steps: stress annealing: a step of subjecting a cold-rolled and molded bearing spring to stress annealing; shot blasting: a step of subjecting the bearing spring having undergone stress annealing to shot blasting; nitriding: a step of filling a nitriding furnace with the bearing spring having undergone shot blasting and carrying out nitriding, wherein nitriding gas is pure ammonia gas, the decomposition rate of ammonia gas is 40 to 50%, nitriding temperature is 370 to 390 DEG C and nitridation time is 12 to 18 h; and denitriding: a step of stopping supply of ammonia gas after completion of nitriding, allowing the bearing spring to remain in the nitriding furnace, maintaining the temperature in the nitriding furnace for 2 to 3 h and carrying out denitriding on the bearing spring having undergone nitriding. The method provided by the invention can realize low-temperature rapid gas nitriding of the 55 SiCr steel bearing spring and enables appropriate residual compressive stress to be maintained on the surface layer of the spring in a certain depth range.
Description
Technical field
The present invention relates to the nitriding method of automotive suspension spring, particularly relate to the nitriding method of 55SiCr steel bearing spring.
Background technology
55SiCr(SUP12) be a kind of spring steel material of high-quality, the tensile strength of steel wire reaches more than 1700MPa, and the design stress of spring can reach more than 1100MPa, has been widely used as high-grade car bearing spring steel at present.Domestic rarely have scientific and technical personnel to carry out the research of gas nitriding aspect to spring steel 55SiCr at present; its topmost reason is that the temperature of conventional nitriding is too high; and 55SiCr spring steel adopts average tempering; microstructure after its normalized tempering is the mixed structure of tempered martensite and tempering troostite; after long nitriding insulation; the tissue of spring steel changes, though workpiece surface defines strengthening layer after nitrogenize, the overall performance of spring steel have dropped.In addition, for the gas nitriding of routine, after nitriding, workpiece surface generally all can form nitride white layer (bright layer), bright layer has important effect for raising workpiece surface hardness and corrosion resistance nature, but for spring in the process of bearing reciprocal repeated load for a long time, the hard and crisp bright layer in surface is easy to crack and cause spring breakage to be lost efficacy.Therefore, wish that spring steel nitriding rear surface does not generate bright layer.
Spring steel low temperature gas nitriding can be good at avoiding produced problem in conventional gas nitriding, by the control of ammonia decomposition in nitriding process and in the nitriding later stage steel part moved back to nitrogen process thus control bright layer thickness and even make surface not generate bright layer.How improving infiltration rate for low temperature gas nitriding is the problem needing solution badly, and spring steel autologous tissue structure and performance requriements nitriding temperature can not higher than 400 DEG C, nitriding temperature is the important factor affecting nitrogen Elements Diffusion speed, nitriding temperature be 300 DEG C and 500 DEG C time micropore diffusion coefficient be respectively 3.50 × 10
-10cm
2/ s, 2.15 × 10
-8cm
2/ s.In theory, when the nitriding speed of 300 DEG C is only 500 DEG C infiltration rate about 1/100.We know that nitrogen-atoms has less diffusion activation energy at crystal boundary and fault location, and its size is only about 0.6 of micropore diffusion intensity of activation, and the crystal boundary that workpiece surface produces after viscous deformation and defect will significantly improve the permeating speed of nitrogen-atoms.For 300 DEG C of nitridings, nitrogen-atoms is 2.06 × 10 along the spread coefficient of crystal boundary
-7cm
2/ s, dot matrix spread coefficient also large order of magnitude during than 500 DEG C.Therefore steel piece surface is through viscous deformation process in advance, refining grain size, increases defect concentration, greatly can improve nitriding speed, realizes nitriding under low temperature environment.
Shot-peening is a kind of widely used material surface Cold-forming process, spring steel surface significantly can promote nitriding speed through shot peening in advance, mainly because spring steel surface creates a large amount of viscous deformation after shot peening, the defects such as the crystal boundary produced by viscous deformation, dislocation and room, as the rapid passage of nitrogen Elements Diffusion, significantly improve the permeating speed of nitrogen-atoms.Therefore spring steel not only can improve the fatigue lifetime of spring but also can improve the speed of spring steel gas nitriding after shot-peening, but just particularly important for the control of shot peening strength.Shot peening strength is low, and cause spring steel internal compressive stress not on the one hand thus the fatigue lifetime of reduction spring, low strength shot-peening is also little to temperature gas nitriding permeating speed castering action on the other hand; Though excessive shot-peening can accelerate nitriding speed, reduce surfaceness, skin-material is sustained damage, instead can reduce fatigue lifetime.Therefore shot peening strength is reasonably controlled most important to the fatigue lifetime and low temperature gas nitriding speed that promote spring.
Summary of the invention
Technical problem to be solved by this invention is the gas nitriding process providing a kind of 55SiCr steel bearing spring, the method can not only realize the low temperature Quick-Nitriding of 55SiCr steel bearing spring, and can keep suitable residual compressive stress within the scope of the certain depth of spring top layer simultaneously.
The technical solution adopted in the present invention is: the gas nitriding process of 55SiCr steel bearing spring, comprises the following steps:
Stress annealing step: the bearing spring after cold rolling forming is carried out stress annealing;
Bead blasting step: shot peening is carried out to the bearing spring after stress annealing;
Nitridation steps: loaded in nitriding furnace by the bearing spring after shot peening and carry out Nitrizing Treatment, wherein, nitriding gas is pure ammonia, and the rate of decomposition of ammonia is 40% ~ 50%, and nitriding temperature is 370 ~ 390 DEG C, and nitridation time is 12 ~ 18 hours.
Move back nitrogen step: after nitriding terminates, stop ammonia supply, make bearing spring nitriding furnace inside holding 2 ~ 3 hours; Undertaken moving back nitrogen process by completing the bearing spring after nitridation steps.
Invention increases the receptivity of workpiece surface to activated nitrogen atom, accelerate the permeating speed of nitrogen-atoms, reduce nitriding temperature, make workpiece surface generate uniform diffusion layer organization, workpiece surface hardness is greater than 660HV
0.025, exceed substrate 120HV
0.025, after low temperature gas nitriding, the performance of 55SiCr steel bearing spring is improved.
Accompanying drawing explanation
Fig. 1 is the schema of a gas nitriding process embodiment of 55SiCr steel bearing spring of the present invention;
Fig. 2 is the infiltration layer microstructure (× 100) through the process of 390 DEG C × 12h low temperature gas nitriding;
Fig. 3 is the infiltration layer microstructure (× 1000) through the process of 390 DEG C × 12h low temperature gas nitriding;
Fig. 4 is the infiltration layer microstructure (× 1000) of 55SiCr steel bearing spring after 390 DEG C × 12h nitriding without shot peening;
Fig. 5 is nitrided layer hardness distribution curve after the process of 390 DEG C × 12h low temperature gas nitriding.
Embodiment
Refer to Fig. 1.The gas nitriding process of 55SiCr steel bearing spring, comprises the following steps:
Stress annealing step: the bearing spring after cold rolling forming is carried out stress annealing; The temperature of stress annealing is 370 ~ 390 DEG C, and the time is 1 ~ 3 hour.
Bead blasting step: shot peening is carried out to the bearing spring after stress annealing.Single shot-peening or secondary shot-peening can be adopted, bullet material is steel wire cut pill, bullet diameter is between 0.8 ~ 1mm, the jet velocity of bullet is 75 ~ 80m/s, shower nozzle is 150 ~ 300mm apart from the distance on the surface of workpiece, the time of single shot-peening is 60 ~ 90 seconds, A Erman-A test piece camber 0.40 ~ 0.55mm.
Nitridation steps: loaded in nitriding furnace by the bearing spring after shot peening and carry out Nitrizing Treatment, batch is 1/3 ~ 1/2 of total retort volume.Wherein, nitriding gas is pure ammonia, and the rate of decomposition of ammonia is 40% ~ 50%, and nitriding temperature is 370 DEG C ~ 390 DEG C, and nitridation time is 12 ~ 18 hours.
Move back nitrogen step: after nitriding terminates, stop ammonia supply, make bearing spring nitriding furnace inside holding 2 ~ 3 hours; Being undertaken moving back nitrogen process by completing the bearing spring after nitridation steps, material surface can be avoided to generate bright layer by moving back nitrogen process.
Invention increases the receptivity of workpiece surface to activated nitrogen atom, accelerate the permeating speed of nitrogen-atoms, reduce nitriding temperature, make workpiece surface generate uniform diffusion layer organization, workpiece surface hardness is greater than 660HV
0.025, exceed substrate 120HV
0.025, after low temperature gas nitriding, the performance of 55SiCr steel bearing spring is improved.
The low temperature gas nitriding of the 55SiCr steel bearing spring that the present invention proposes and common spring surface carry out low temperature gas nitriding after shot-peening or nanometer process following difference:
The first, the present invention is the low temperature gas nitriding treatment process being specifically applied to this special rolling-mill section of 55SiCr;
The second, in the present invention before low temperature nitriding through the normal procedure that shot peening is in advance spring Production Flow Chart, instead of extra processing is carried out to spring surface;
Three, the various process parameters in the present invention such as shot peening strength, nitriding temperature and nitriding time etc. are for designed by this special steel grade of 55SiCr spring steel, both can obtain certain thickness strengthening layer through low temperature gas nitriding rear spring surface, and there is sizeable stress simultaneously within the scope of the following certain depth in top layer.
Below in conjunction with two specific embodiments, the present invention is described in further detail.Fig. 2 ~ Fig. 4 is the accompanying drawing in embodiment 1.
Embodiment 1
The composition of 55SiCr spring steel is as shown in the table (wt%):
After wire rod 55SiCr spring steel (wire diameter is 12.2mm) cold rolling forming, to represent hour through 385 DEG C × 1.5h(h) stress relief annealing.Send into shotblasting machine subsequently and carry out shot-peening, adopt " horizontal type rotation " secondary shot peening, the single shot-peening time is 60s, shot-peening total time is 120s, bullet is the steel wire cut pill of diameter between 0.8 ~ 1mm, and jet velocity is 75m/s, and shower nozzle is 250mm apart from the distance on the surface of workpiece, shot-peening fraction of coverage is 200%, A Erman-A test piece camber 0.50mm.
Surface-brightening spring after shot-peening is directly loaded nitriding furnace, batch is 1/3 of retort volume, nitriding adopts pure ammonia atmosphere, adopts staged to heat up for holding workpiece temperature is synchronous with in-furnace temperature before reaching nitriding temperature, and temperature often raises 100 DEG C and is incubated half an hour.Nitriding temperature is 390 DEG C, and ammonia decomposition is 50%, and nitriding is incubated 12 hours, and nitriding insulation terminates the supply of rear stopping ammonia, then is incubated 3 hours, after be down to room temperature with stove.As a comparison, Nitrizing Treatment is carried out by same nitridation process effects on surface without the spring steel of shot peening.
Alloying layer thickness finally through shot peening sample reaches 120 μm, and surface microhardness reaches 663.7HV
0.025, exceed the nearly 120HV of substrate
0.025, reach 0.492% (wt) apart from the nitrogen element content at 20 μm, surface place, the dominant phase composite of nitrided case is a large amount of nitrogenous α-Fe phase, γ '-Fe
4n phase, CrN phase and a small amount of Fe
3o
4phase.Workpiece surface does not generate bright layer, and metallographicobservation display infiltration layer has uniform weave construction, and nitrided case is made up of diffusion layer and transition layer, and the metal nitride highly dispersed that diffusion layer is mainly in black is distributed in nitrogenize martensite.Without the spring steel of shot peening, almost do not form strengthening layer in nitrogenize rear surface, surface hardness does not promote.
Embodiment 2
Carry out shot peening to the 55SiCr spring steel of same sample ingredient, adopt single shot-peening, shot-peening fraction of coverage is 100%, and shot-peening total time is 60 seconds, and A Erman-A test piece camber 0.40mm, other shot-peening parameters are with embodiment 1.Shot peening strength comparatively embodiment 1 declines to some extent.
Carry out low temperature gas nitriding according to the technique in embodiment 1, nitriding temperature is 370 DEG C, lower than embodiment 1 20 DEG C.
The alloying layer thickness of final sample is about 60 μm, and surface hardness is 597.4HV
0.025, exceed substrate 50HV
0.025left and right, the nitrogen content apart from 20 μm, surface place is 0.259% (wt), and the dominant phase of nitrided case is identical with embodiment 1.
Claims (7)
- The gas nitriding process of 1.55SiCr steel bearing spring, is characterized in that, comprising:Stress annealing step: the bearing spring after cold rolling forming is carried out stress annealing;Bead blasting step: shot peening is carried out to the bearing spring after stress annealing;Nitridation steps: loaded in nitriding furnace by the bearing spring after shot peening and carry out Nitrizing Treatment, wherein, nitriding gas is pure ammonia, and the rate of decomposition of ammonia is 40% ~ 50%, and nitriding temperature is 370 DEG C ~ 390 DEG C, and nitridation time is 12 ~ 18 hours.Move back nitrogen step: after nitriding terminates, stop ammonia supply, make bearing spring nitriding furnace inside holding 2 ~ 3 hours; Undertaken moving back nitrogen process by completing the bearing spring after nitridation steps.
- 2. gas nitriding process as claimed in claim 1, it is characterized in that, in described stress annealing step, the temperature of stress annealing is 370 ~ 390 DEG C, and the time is 1 ~ 3 hour.
- 3. gas nitriding process as claimed in claim 1, is characterized in that, in described bead blasting step, employing be single shot-peening, bullet diameter is between 0.8 ~ 1mm, and the shot-peening time is 60 ~ 90 seconds.
- 4. gas nitriding process as claimed in claim 1, is characterized in that, in described bead blasting step, employing be secondary shot-peening, bullet diameter is between 0.8 ~ 1mm, and the single shot-peening time is 60 ~ 90 seconds.
- 5. the gas nitriding process as described in claim 3 or 4, is characterized in that, in described bead blasting step, the jet velocity of bullet is 75 ~ 80m/s, and shower nozzle is 150 ~ 300mm, A Erman-A test piece camber, 0.40 ~ 0.55mm apart from the distance on the surface of workpiece.
- 6. gas nitriding process as claimed in claim 1, it is characterized in that, in described nitridation steps, furnace temperature adopted staged to heat up before reaching nitriding temperature.
- 7. gas nitriding process as claimed in claim 1, it is characterized in that, in described nitridation steps, the batch of bearing spring is 1/3 ~ 1/2 of total retort volume.
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| CN201310654829.9A CN104694872B (en) | 2013-12-05 | 2013-12-05 | The gas nitriding process of 55SiCr steel bearing springs |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108554755A (en) * | 2018-06-16 | 2018-09-21 | 宁波明望汽车饰件有限公司 | A kind of auto parts machinery surface intensified technique |
| CN109457087A (en) * | 2018-12-26 | 2019-03-12 | 太原理工大学 | A kind of process preparing intermetallic compound coating in metal surface |
| CN109576631A (en) * | 2018-10-29 | 2019-04-05 | 山东建筑大学 | A kind of workpiece surface reinforcing new method |
| CN109652757A (en) * | 2018-12-28 | 2019-04-19 | 宁波合力模具科技股份有限公司 | A kind of high vacuum squeezes the surface recombination processing method of compression mod |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1159487A (en) * | 1996-03-09 | 1997-09-17 | 住友电气工业株式会社 | Spring having high nitrided properties and method for manufacturing the same |
| CN101642867A (en) * | 2009-07-30 | 2010-02-10 | 杭州钱江弹簧有限公司 | Technique for processing engine valve spring |
| CN102822557A (en) * | 2010-03-23 | 2012-12-12 | 中央发条株式会社 | Method for producing spring |
| JP2013050195A (en) * | 2011-08-31 | 2013-03-14 | Sumitomo Electric Ind Ltd | Spring steel wire and spring |
-
2013
- 2013-12-05 CN CN201310654829.9A patent/CN104694872B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1159487A (en) * | 1996-03-09 | 1997-09-17 | 住友电气工业株式会社 | Spring having high nitrided properties and method for manufacturing the same |
| CN101642867A (en) * | 2009-07-30 | 2010-02-10 | 杭州钱江弹簧有限公司 | Technique for processing engine valve spring |
| CN102822557A (en) * | 2010-03-23 | 2012-12-12 | 中央发条株式会社 | Method for producing spring |
| JP2013050195A (en) * | 2011-08-31 | 2013-03-14 | Sumitomo Electric Ind Ltd | Spring steel wire and spring |
Non-Patent Citations (3)
| Title |
|---|
| 杨伟明 等: ""螺旋弹簧的表面强化问题"", 《第十三届全国弹簧学术会、第十一届全国弹簧失效分析讨论会暨第七届海峡两岸弹簧专业研讨会论文集》 * |
| 火树鹏 编著: "《钢的气体氮化》", 30 November 1984, 机械工业出版社 * |
| 谢乐春 等: ""弹簧材料的几种实用喷丸技术的探讨"", 《第十三届全国弹簧学术会、第十一届全国弹簧失效分析讨论会暨第七届海峡两岸弹簧专业研讨会论文集》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108554755A (en) * | 2018-06-16 | 2018-09-21 | 宁波明望汽车饰件有限公司 | A kind of auto parts machinery surface intensified technique |
| CN109576631A (en) * | 2018-10-29 | 2019-04-05 | 山东建筑大学 | A kind of workpiece surface reinforcing new method |
| CN109457087A (en) * | 2018-12-26 | 2019-03-12 | 太原理工大学 | A kind of process preparing intermetallic compound coating in metal surface |
| CN109652757A (en) * | 2018-12-28 | 2019-04-19 | 宁波合力模具科技股份有限公司 | A kind of high vacuum squeezes the surface recombination processing method of compression mod |
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