正火预热处理对42CrMo曲轴钢调质后的组织与性能影响

利用金相显微观察及力学性能分析,研究调质处理、正火+调质热处理对42CrMo曲轴钢组织与性能的影响。结果表明,经过860℃淬火+580℃回火处理后,曲轴钢基体组织为回火索氏体,但轴颈心部区域白色铁素体数量较多且晶粒粗大、分布不均。其力学性能为抗拉强度997～1211 MPa,屈服强度990～1204 MPa,伸长率11%～13%,断面收缩率40%～48%,冲击功72～90 J。而在调质热处理前增加一次(880℃空冷)正火预处理后,42CrMo曲轴钢的显微组织更趋均匀化,其力学性能为抗拉强度1100～1220 MPa,屈服强度1107～1188 MPa,伸长率13%～15%,断面收缩率50%～56%,冲击功83-91 J。因此,880℃空冷正火预处理+860℃淬火与580℃高温回火是42CrMo曲轴钢优化的热处理工艺。     

原始组织对690 MPa级海工钢亚温淬火后强韧性的影响

 为了稳定亚温淬火工艺与工业化生产,通过力学性能分析及显微组织观察,对比了正火+亚温淬火+回火、在线淬火+亚温淬火+回火、离线淬火+亚温淬火+回火3种热处理工艺对690 MPa级海洋工程用钢板组织性能的影响。结果表明,采用离线淬火+亚温淬火+回火工艺结果最理想,能够大幅度提高钢板的低温冲击性能和伸长率。同时,还能够获得较低的屈强比,断口形貌全部为韧窝,呈明显的韧性断裂,而且随着亚温保温时间的增加,强度逐渐提高,当保温时间达到30 min以后,强度及条片状铁素体基本不发生变化;采用直接淬火态+亚温淬火+回火虽然可以保证高强度低屈强比,但是冲击功表现较为离散,稳定性欠佳,断口形貌为混合型,以韧性断裂为主;采用正火态+亚温淬火+回火工艺效果最差,尤其是不能保证钢板低温韧性,断口形貌全部为解理,呈明显的脆性断裂,其中片条状铁素体形貌是决定优良低温冲击性能的关键因素。     

热处理工艺对海洋工程用高强度耐低温H型钢组织及性能影响

摘要：以热轧耐低温H型钢为研究对象,采用光学显微镜、扫描电镜、透射电镜分析和力学性能测试等手段,研究了完全淬火和亚温淬火对试验钢微观组织和力学性能的演变规律。结果表明,试验型钢经780℃亚温淬火+600℃回火处理后,形成回火索氏体+铁素体的网状组织;试验型钢900℃淬火+600℃回火处理后,转变得到具有马氏体位向的回火索氏体,碳化物分布更加细小均匀,位错密度下降。2种热处理工艺制备H型钢综合力学性能优良,屈服强度均达到500MPa以上,900℃淬火+600℃回火处理后钢的屈服强度和抗拉强度更高。-40℃低温冲击韧性比热轧状态下出现大幅度提高,随着淬火温度升高冲击功更加稳定。     

150 mm超厚水电站用钢07MnCrMoVR的组织性能

对150 mm超厚07MnCrMoVR水电钢的组织性能进行了研究,采用光学显微镜、扫描电子显微镜对试验钢的微观形貌进行了观察,采用拉伸试验机和低温冲击韧性试验机对试验钢力学性能进行了检验。结果表明:试验钢经第一次完全淬火和第二次两相区亚温临界淬火后近表面组织转变为板条马氏体和未熔铁素体相间出现,厚度1/4处和厚度1/2处组织转变为贝氏体+铁素体组织,高温回火后近表面转变为回火索氏体组织,厚度1/4处和厚度1/2处组织转变为回火贝氏体+铁素体+大量碳化物。     

150mm超厚水电站用钢07MnCrMoVR的组织性能

摘要：对150mm超厚07MnCrMoVR水电钢的组织性能进行了研究，采用光学显微镜、扫描电子显微镜对试验钢的微观形貌进行了观察，采用拉伸试验机和低温冲击韧性试验机对试验钢力学性能进行了检验。结果表明：试验钢经第一次完全淬火和第二次两相区亚温临界淬火后近表面组织转变为板条马氏体和未熔铁素体相间出现，厚度1/4处和厚度1/2处组织转变为贝氏体+铁素体组织，高温回火后近表面转变为回火索氏体组织，厚度1/4处和厚度1/2处组织转变为回火贝氏体+铁素体+大量碳化物。     

用亚温淬火改善35CrMo钢的氢脆敏感性

本文研究了亚温淬火工艺对35CrMo钢力学性能和抗氢脆性能的影响。试验结果表明,当亚温淬温度高于790℃,即钢中残留的铁素体量低于11.2％时,经高温回火的35CrMo钢的抗拉强度、屈服强度以及常温冲击韧性都有明显的提高,钢的氢脆敏感性得到改善。文中分析了性能改善的原因,初步认为亚温淬火细化了晶粒和组织,是各项性能获得改善的主要原因。     

铌对低温钢组织及性能的影响

通过金相组织观察、低温冲击试验和拉伸试验及拉伸断口形貌观察,研究了铌对正火+调质处理低温钢组织及性能的影响。结果表明:铸态下随着试样中铌含量的增加,组织中珠光体片间距逐渐减小,经过930℃正火+900℃淬火+630℃回火热处理后,铌质量分数为0.039%的试样组织及综合性能最佳,组织为回火索氏体,-20、-40℃夏比冲击功分别达到44.4和28.4J,抗拉强度和屈服强度分别为995和885MPa,断后伸长率达到17.0%。     

调整热处理工艺保证25MnV钢石油套管质量

针对25MnV钢石油套管调质处理后冲击韧性偏低且不稳定的问题,进行了改进的亚温淬火工艺试验,生产应用结果表明,与常规热处理相比,亚温淬火后的25MnV钢可得到板条马氏体之间分布有条状铁素体的复相组织,在不降低强度的前提下,明显提高冲击韧性,抑制高温回火脆性。     

正火预处理对调质26CrMoV钢φ195mm棒材横向-20℃冲击功的改善

对直径为 φ195 mm 的Ti-V微合金化26CrMoV 钢(/% ：0.27C,0.45Mn,0.25Si,0.006P,;0.004S, 0.97Cr,0.78Mo,0.002Ti,0.043V)热轧棒材取样后在热处理试验室分别按880 ℃淬火+645℃回火和925℃正火+880℃淬火+645℃回火两种工艺进行热处理。通过检测其皮下25.4 mm处力学性能,发现两种热处理工艺试样的屈服及抗拉强度相近,淬火+回火处理的-20 ℃横向冲击为46 ~47 J 而正火+淬火+回火处理的-20 ℃横向冲击功为79~86 J,改善效果明显。对比观察发现经正火预处理后钢的回火索氏体及铁素体组织更加均匀、细小。     

1Cr17Ni2钢的高温回火脆性

研究了亚温淬火对１Ｃｒ１７Ｎｉ２钢高温回火脆性的影响。结果表明，亚温淬火能有效地抑制该钢的高温回火脆性。经亚温淬火后，钢的脆性转化温度降低，韧性得到改善，断口形貌由准解理型变为韧窝型，合金元素向基体和δ铁素体中的富集程度增大，在改善钢的韧性的同时仍保持较高的强度水平。     

Induction Hardening of Spur Gearwheels Made from 42CrMo4 Hardening and Tempering Steel by Employing Spray Cooling

As a rule, induction surface hardening is carried out industrially by employing polymer solutions since these ensure a more homogeneous quench than immersion cooling in water. Besides reproducing the quenching process, the intention here is to minimise the hardening defects and the distortions arising from the heat treatment. Polymer solutions also have a few disadvantages which include, among others, poor environmental compatibility and handleability. Quenching by means of spray cooling provides an effective alternative. The purpose of the current investigation is to substitute the polymer solution by a water‐air spray in induction hardening equipment for surface hardening spur gearwheels made of 42CrMo4 hardening and tempering steel. The suitability of spray cooling was assessed by means of hardness measurements, residual stress conditions, distortion measurements and by metallographic examinations. Based on the analyses currently carried out, it was possible to show that the two‐phase spray cooling represents an alternative quenching method which produces comparable component properties.     

Cr含量对G18CrMo2-6钢组织和性能的影响

通过热处理试验、微观组织表征和力学性能检测,对比研究了在不同Cr含量的情况下,G18CrMo2-6钢微观组织形貌、力学性能的变化.结果表明,随着合金元素Cr含量增加,同一温度退火热处理后G18CrMo2-6钢中铁素体体积分数减少,贝氏体增多,从而导致材料强度升高;但是Cr含量的增加还会导致该类材料退火产生的贝氏体中马氏...     

Effect of tempering on mechanical properties of 25Co15Ni11Cr2MoE steel

The change rule of mechanical properties and impact fracture morphologies of a high Co- Ni secondary hardening ultra- high strength 25Co15Ni11Cr2MoE steel tempered at 200-750?? after quenched was studied by mechanical properties test and microstructure analysis such as optical microscope(OM) and scanning electron microscope(SEM). The results show that experimental steel after quenching and tempering has a remarkable secondary hardening effect. After tempered at 400-495??, the hardness of experimental steel can reach and beyond the quenched hardness. In this range, tensile strength, yield strength and hardness of experimental steel increase with the tempering temperature increasing, tensile strength and hardness of experimental reach maximum (57. 3HRC and 2160MPa) after tempered at 470??, meanwhile, with the tempering temperature increasing, impact toughness of experimental steel decreases during the prophase, until reaches minimum at 430??, then increases gradually, and reaches maximum after tempered at 510??. The recommended optimum heat treatment process of 25Co15Ni11Cr2MoE steel is as follow: 950???1h oil quenching??(-73??)??1h rising back to room temperature in the air ??495???5h air cooling. At this time, the experimental steel has the best strength and toughness matching.     

Effect of quenching temperature on microstructure and fracture toughness of high carbon steel

The effect of quenching temperatures on microstructure and fracture toughness of high carbon steel was investigated. Plane strain fracture toughness was tested with compact tension specimen. Microstructure and fracture morphology of KIC samples after quenching and tempering treatment were examined by scanning electron microscope (SEM).The results show that the residual carbides of steel in hardened state decreasea with the quenching temperature increasing and totally disappear after quenched at 920??;the grain size grows up obviously when the quenching temperature is more than 960??. The microstructure in high temperature tempered state is composed of residual carbides, precipitated carbides and ferrite matrix;plasticity decreases monotonically; the fracture toughness gradually decreases in the range from 800?? to 960??,and then almost invariant; the fracture type of KIC specimens is gradually changed from cleavage fracture to intergranular fracture. The main reason for the changes of fracture toughness has close relationship with the plasticity.     

热处理工艺对2Cr11Mo1VNbN耐热钢组织和性能的影响

 为了解决2Cr11Mo1VNbN钢短时持久性能低的问题,采用OM、SEM、TEM等手段研究了不同淬火和回火工艺下超超临界叶片用2Cr11Mo1VNbN马氏体耐热钢的组织、室温力学性能及短时持久性能。结果表明,随着淬火温度的提升,强度和硬度增加,冲击吸收功在1 075 ℃后呈降低趋势;1 125 ℃淬火+660 ℃回火后,该钢的649 ℃+228 MPa的短时持久性能明显提升。回火温度高于660 ℃,强度和硬度降低,冲击吸收功增加,短时持久性能急速衰减。微观组织分析表明,提高淬火温度,合金中的一次粗大铌的碳化物更多地固溶到基体中,析出数量减少,固溶强化作用增加,强度和硬度增加,使合金的弱化区减少,提高了材料抵抗高温变形的能力,改善了合金的持久性能。     

Mn2钢低温韧性变化规律研究

对Mn2钢在不同热处理工艺、不同试验温度和不同试样状态下的冲击韧性进行了详细的分析,结果表明:CM690钢在900℃保温90 min水冷淬火,600℃保温90 min水冷回火,在保证钢材的强度满足要求的情况下,可获得良好的韧性;淬火水温超过30℃时,因钢的淬透能力下降,会强烈地降低钢的强度和韧性;钢中加入0.015%~0.025%的Ti,提高冲击韧性值35~40 J;对于CM490钢,若轧后空冷或堆冷,由于冷却速度较低,会获得铁素体+珠光体+贝氏体的混合组织,不利于提高钢材的韧性,而正火后其组织为铁素体+贝氏体,其冲击值比前两种状态高3~5倍。     

热处理工艺对40CrMnMo钢低温冲击韧性的影响

通过不同的热处理制度:800、820℃低温淬火+600℃回火,880℃+860℃两次淬火+600℃回火和860℃一次淬火+600℃回火,对40CrMnMo钢进行热处理试验,并研究了三种热处理工艺对40CrMnMo试验钢组织和性能的影响。结果表明,三种热处理工艺的试验钢抗拉强度相近(936～951 MPa),组织为回火马氏体+铁素体,采用800、820℃低温淬火+600℃回火热处理工艺,试验钢的冲击功最高(65～69J)。     

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On- line quenching and self tempering is the advanced technology in the production of large bars. Considering the latent heat of phase transformation and the changes of thermal physical properties of material with temperature, the temperature fields of online quenching and air cooling process after rolling of large diameter bars (more than 50mm in diameter) of 45 steel and 42CrMo with different specifications were simulated with the finite element software MSC. Marc. The critical cooling speeds of quenching were calculated to obtain the maximum depths of hardened layers of bars with different diameters and the related hardening time needed for forming maximum depth of hardened layer. The temperature fields of the bars after different quenching time were studied, meanwhile, the possibility of self- tempering was analyzed.