42CrMo4钢板冷弯曲中断裂原因分析

利用金相显微镜和扫描电镜等分析方法,对42CrMo4钢板冷弯曲中断裂原因进行分析。结果表明,断裂钢板内部存在严重的组织缺陷,钢板局部区域存在马氏体组织、孔洞、严重的组织偏析和较大尺寸的钛颗粒夹杂,这些因素导致该区域组织应力和脆性较大,成为钢板内部的裂纹源,在弯曲成形过程中的拉应力作用下产生裂纹,并不断扩展导致钢板断裂。     

Influence of Normal Load, Sliding Speed and Ambient Temperature on Wear Resistance of ZG42CrMo

 Abstract： To investigate the wear resistance of ZG42CrMo in industrial application, the wear behaviors under different normal loads, sliding speeds and ambient temperatures were simulated by an MMU-5G abrasion tester to acquire the friction coefficients and wear rates, with the morphology of worn surface observed by scanning electron microscopy (SEM) and chemical composition of worn surface and debris analyzed by X-ray energy dispersive spectroscopy (EDS). Combine with the theory of tribology, finally the regular of environmental factors′ influence on material wear behaviors is determined. The results show that the increase of load decreases wear resistance significantly, when the pressure reaches a certain extent, severe spalling occurs on the worn surface; the changes of speed result in the changes of size of abrasive debris, and then effect the wear behaviors, in the increasing process of speed, the wear rate increases firstly and then decreases; the rise of temperature causes changes in wear mechanism, bring forth oxidation film on the worn surface, which leads to significant improvement of the wear resistance of materials under high temperature compared to that under low temperature.     

42CrMo表面裂纹的分析与改进

针对采用矩形坯轧制棒材42CrMo生产中出现的表面裂纹缺陷,通过对棒材表面裂纹和棒材质量的分析,认为是铸坯表面裂纹导致棒材表面裂纹缺陷的产生,并且裂纹的产生是由于连铸工艺参数的不合理引起的。通过对连铸工艺的改进,合理优化结晶器电磁搅拌参数、二冷配水和拉坯速度,消除了铸坯表面裂纹,从而解决了棒材表面裂纹的缺陷。     

非金属夹杂物对天然气油井用35CrMo钢耐蚀性的影响

天然气井油管悬挂器用 3 5CrMo钢的腐蚀失效分析和含CO2 、水、盐介质的盐雾试验表明 ,3 5CrMo钢表面的非金属夹杂附近形成的电化学腐蚀坑是应力腐蚀裂纹源     

42CrMo钢曲轴锻件表面裂纹形成机理分析和工艺改进

对865℃1.5 h油淬+640℃4 h回火、水冷的42CrMo钢(/%:0.43C,0.77Mn,0.24Si,0.014P,0.007S,1.08Cr,0.17Mo,0.01Cu)曲轴锻件表面裂纹形成进行了分析。结果表明,曲轴锻件表面裂纹为淬火裂纹,回火时间不足(4 h)和锻件存在较严重的带状组织(3级)是该曲轴产生淬火裂纹的主要原因。通过将回火时间延长至5 h,控制带状组织≤2级,曲轴调质后未发现裂纹,产品合格率达100%。     

42CrMo钢的贝氏体组织相变

采用金相法研究了经950℃奥氏体化的0．41C-1．OCr-0．23Mo(42rMo)钢在550～380℃盐浴等温处理时贝氏体组织转变。观察结果表明，42CrMo钢550～510。c等温处理的组织为无碳贝氏体(粗大条片状贝氏体铁素体 残留奥氏体组成的整合组织) 马氏体，470℃等温处理为羽毛状上贝氏体 黑色针状下贝氏体 马氏体组织，380℃为黑色针状下贝氏体 马氏体组织；上贝氏体在奥氏体晶界形核，随等温处理的温度降低，下贝氏体在奥氏体晶内形核。     

对42CrMo钢锻件白点缺陷的超声波探伤

介绍了对大型钢锻件的超声波检测情况,以及对检测中发现的白点缺陷进行了全面的验证分析。     

硅、锰对中碳CRMo低合金钢淬透性和耐磨性的影响

中碳CrMo低合金钢作为一种耐磨材料广泛应用于球磨机衬板,但因其淬透性有限,限制了其在大型衬板上的使用,通过研究硅,锰含量对中碳CrMo低合金钢淬透性的影响,发现适当设计硅,锰含量可使该钢种的耐磨性大大提高。     

三种耐蚀塑料模具钢的耐磨性和磨损机理

通过M200环-块磨损试验机和扫描电镜研究了具有良好耐腐蚀性能的3种塑料模具钢STAVAX (%:0.37C、13.40Cr、0.31V)、M330(%:0.36C、12.88Cr、0.15Mo)和N702(%:0.05C、16.30Cr、4.00Cu、4.00Ni、0.34Nb)的磨损性能和磨损表面形貌。结果表明,STAVAX、M330和N702钢在淬、回火后HRC值分别为55、53和44,磨痕宽度分别为2.61 mm、2.74 mm和7.41 mm。STAVAX和M330钢组织为基体+细球状碳化物,具有较高的耐磨性,而N702钢的基体相对较软,无第二相碳化物,在试验过程中其基体极易磨损,形成大量疲劳裂纹,易导致块状或片状剥落,耐磨性较低。     

风电齿圈用钢F42CrMo4探伤缺陷分析和工艺改进

F42CrMo4钢风电齿圈的生产工艺流程为热装铁水-100 t EAF-LF-VD-Φ500 mm CCM-缓冷-锻制成Φ2000～3900 mm环形锻件。对探伤不合格的风电齿圈缺陷部位运用超声波进行定位取样,分析表明,氧化铝类夹杂物以及铸坯疏松缺陷,是造成部分批次风电齿圈用F42CrMo4钢探伤不合格的主要原因。通过控制电弧炉终点碳≥0.15%,LF终点喂钙线0.50 kg/t,喂钙后软吹氩≥10 min,VD后氩气流量由2×25 L/min增加至2×30 L/min,控制钢水过热度10～18℃等工艺措施使钢中氮、氢和氧含量分别由原≤80×10^-6、≤1.5×10^-6和≤20×10^-6降低到≤75×10^-6、≤1.2×10^-6和≤15×10^-6,锻件探伤合格率提高到98.95%以上。     

Effects of the Process Parameters on the Microstructure and Properties of Nitrided 17-4PH Stainless Steel

The effects of process parameters on the microstructure, microhardness, and dry-sliding wear behavior of plasma nitrided 17-4PH stainless steel were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and wear testing. The results show that a wear-resistant nitrided layer was formed on the surface of direct current plasma nitrided 17-4PH martensitic stainless steel. The microstructure and thickness of the nitrided layer is dependent on the treatment temperature rather than process pressure. XRD indicated that a single α _N phase was formed during nitriding at 623 K (350 °C). When the temperature increased, the α _N phase disappeared and CrN transformed in the nitrided layer. The hardness measurement demonstrated that the hardness of the stainless substrate steel increased from 320 HV_0.1 in the untreated condition increasing to about 1275HV_0.1 after nitriding 623 K (350 °C)/600 pa/4 hours. The extremely high values of the microhardness achieved by the great misfit-induced stress fields associated with the plenty of dislocation group and stacking fault. Dry-sliding wear resistance was improved by DC plasma nitriding. The best wear-resistance performance of a nitrided sample was obtained after nitriding at 673 K (350 °C), when the single α _N-phase was produced and there were no CrN precipitates in the nitrided layer.     

H型钢轧制过程中表面氧化皮耐蚀性能研究

为研究H型钢表面氧化皮在轧制过程中的形貌变化及其对耐蚀性能的影响,利用扫描电镜(SEM)对其进行了观察,发现粗轧后氧化皮与基体的结合疏松。通过自然腐蚀电位、极化曲线和电化学阻抗等电化学测试方法,研究了H型钢表面氧化皮的耐腐蚀性能变化。结果表明:粗轧后样品由于残留氧化铁皮压入,破坏了氧化皮的致密结构,耐蚀性能下降,精轧后样品氧化皮对基体的保护作用较强,耐蚀性能提高。     

Effect of Rare Earth Elements on Erosion Resistance of Nitrocarburized Layers of 38CrMoAl Steel

Effect of rare earth elements (RE) on erosion resistance of nitrocarburized layer of 38CrMoAl steel was investigated. The results indicate that significant improvement occurs in erosion resistance of nitrocarburized 38CrMoAl steel by introducing RE during nitrocarburizing processing as compared with conventional nitrocarburizing processing. Results of mechanical testing show that both hardness and impact toughness of RE-nitrocarburizing layer of 38CrMoAl steel increase as compared with the conventional one. Optical microscopy reveals that there is improvement in the nitrocarburized layer attributed to the introduction of RE, which results in improvement in erosion resistance. Surface morphology observation of tested samples reveals that predominantly furrow-like peelings from plastic deformation are observed for RE nitrocarburizied 38CrMoAl steel, while the furrow-like peeling with initial cross crack and large grinding peelings were observed for conventionally nitrocarburized samples.     

Manufacturing Surface Hardened Components of 42CrMo4 by Water‐Air Spray Cooling

By employing integrated heat‐treatment using forging heat, a significant shortening of the process chain is attained for manufacturing precision forged components with considerable savings in time and energy. With the aid of water‐air spray cooling, surface hardening and tempering can be carried out without, at the same time, reheating the component following quenching. In this work, geometric models of splines and single cylinder crankshafts (both made of 1.7225) were surface hardened and tempered using a purpose‐built rotating spray unit. The obtained hardness, microstructures and their distortions were investigated. To optically and spatially detect the components, fringe and shadow projection systems were employed. In a second research topic, the influence of the spray parameters on the component's distortion was investigated. For both components; the splined shaft and the crankshaft geometries, it was possible to carry out successful surface heat‐treatments using these processes.     

Effects of Ultrasonic Nanocrystal Surface Modification on the Residual Stress,Microstructure, and Corrosion Resistance of 304 Stainless Steel Welds

Metallurgical and Materials Transactions A - In this study, ultrasonic nanocrystal surface modification (UNSM) of 304 stainless steel welds was carried out. UNSM effectively eliminates the tensile...     

稀土对B450NbRE钢耐大气腐蚀性能的影响

通过真空感应炉模拟实验,结合周期浸润腐蚀实验、电化学实验和X衍射分析,研究稀土对于B450NbRE钢耐大气腐蚀性能的影响作用.研究表明,微量的稀土具有改善B450NbRE钢耐大气腐蚀性能的作用.在本实验条件下,当稀土含量为0.0048%～0.0075%时,B450NbRE钢的耐大气腐蚀性能较为良好.稀土可以促进B450NbRE钢锈层中的Fe3O4和δ-FeOOH向γ-FeOOH的转化.     

42CrMo合金结构钢大方坯连铸工艺研究与应用

攀钢采用大方坯连铸工艺生产42CrMo合金结构钢取得明显效果。简介了它所采取的转炉冶炼、LF＋RH精炼、连铸的技术方案以及试验结果。生产实践证明,铸坯表面质量良好,成分偏析度可控制在0.96～1.03,中心疏松和中心偏析均不大于1.0级,w(T.O)≤15×10-6,w(H)≤1.8×10-6。     

韶钢转炉冶炼42CrMo钢的生产实践

韶钢通过设备改进及工艺优化,产品实现了从普通钢向特殊钢的转型,在42CrMo钢的冶炼过程中采取转炉高拉碳、精炼渣系优化、真空脱气等工艺措施,并在连铸工序对连铸参数进行控制,最终生产出性能等方面完全满足客户高质量要求的42CrMo钢.