3Cr2W8V钢气门模具热处理新工艺

近年来,国内研究出不少热作模具钢,但是由于供货困难和价格较贵等方面的原因,在气门生产厂家的应用还不很普遍。而3Cr2W8V钢制造的气门模具（图 1）,因具有较高的耐热疲劳性和热弹性,所以现阶段用于气成型的模具材料,仍然以3Cr2W8V钢为主。 气门模具的工作条件恶劣,每分钟要经10多次激冷激热的变化,而且承受较大的冲击力。因此要提高3Cr2W8V气门模具的寿命,防止其早期开裂,必须在热处理工艺方面加强探索。     

热处理工艺对20Cr1Mo1V1紧固件性能的影响

我国电力工业正进入世界先进水平的行列，对锅炉使用的材料，提出了更高的要求，螺栓钢是锅炉装置中阀门及法兰的接合面所用的关键材料之一，本试验对紧固件用钢20CrMo1V1进行了一系列热处理试验，并用扫描电镜和透射电镜对其断口及组织进行了观察，采用电解萃取的方法用X光衍射仪对碳化物进行了确定，从而找出了最佳热处理工艺。     

2Cr12NiMo1W1V钢螺栓表面裂纹分析

2Cr12NiMo1W1V钢螺栓在调制后发现其表面存在多条轴向裂纹。通过对裂纹进行宏观观察、断口宏观及微观分析、化学成分分析、硬度检查以及金相分析等,并结合实际生产工艺,最终确定了螺栓的开裂原因。分析结果表明:2Cr12NiMo1W1V钢螺栓开裂主要是因为其表面存在锻造折叠缺陷,缺陷处形成裂纹源区,淬火时在淬火应力的作用下,由折叠缺陷进一步扩展形成裂纹。     

2Cr12NiMo1W1V钢补焊焊缝氮化层性能分析

2Cr12NiMo1W1V钢在汽轮机行业应用于阀杆、阀碟、扩散器等零部件时,常因小缺陷而报废。通过在2Cr12NiMo1W1V试板上模拟同质焊补试验和渗氮试验,研究了焊缝金属氮化层的性能,表明焊缝金属的氮化层硬度、深度和脆性均能够满足使用要求,说明该试验结果具有工程应用价值,为此类缺陷的修复提供参考依据。     

气门凹模热处理工艺的改进

本文介绍了3Cr2W8V气门凹模在生产中经过二次改进的过程和三种不同热处理工艺后模具的性能；阐述了模具在生产中出现的问题及解决办法。     

省煤器蛇形管撑架用1Cr20Ni14Si2扁钢压制开裂的原因分析

本文对陕西精密合金股份有限责任公司供货的 4mm× 6 0mm扁钢的原材料 1Cr2 0Ni14Si2进行了试验 ,发现在生产过程中 ,由于该扁钢横弯力学性能较差 ,造成在冲压过程中局部变形过大 ,导致压制开裂。本文就开裂的原因进行了分析 ,并提出了改进方法。     

汽轮机焊接转子接头残余应力研究二:带有弹性槽的30Cr2Ni4MoV模拟件热处理前后残余应力变化

在测试25Cr2Ni2MoV钢核电转子模拟件外圆、内圆、剖面处热处理前后的残余应力分布的基础上,进一步研究了弹性槽对根部打底焊缝处残余应力的影响,测量了盖面焊缝下方4～5层焊道处残余应力的分布。结果表明,弹性槽对缓解根部应力有显著作用,盖面焊缝下方4～5层焊道处存在超过屈服极限的纵向拉应力;热处理后,残余应力大大降低,且保持较好的应力状态。相关测量工作肯定了实际生产工艺对控制残余应力的有效性。     

用铝高速钢加工高温合金(GH698)

介绍了铝高速钢加工高温合金的切削特点,并对磨损机理进行分析,给出合理的刀具几何参数。     

高温氧化对30Cr1Mo1V钢蠕变-疲劳裂纹扩展速率的影响

在室温、540℃和650℃下,分别研究了空气或氩气气氛中氧化对30Cr1Mo1V钢蠕变-疲劳裂纹扩展速率的影响.结果表明:在高温下,在空气中和加载频率较低时,30Cr1Mo1V钢的裂纹扩展速率均明显增加.在加载过程中引入保载时间,空气中30Cr1Mo1V钢的裂纹扩展速率明显高于惰性环境中,说明氧化影响着疲劳裂纹扩展行为.在惰性气氛中,裂纹扩展速率随保载时间的延长而增大.在空气中,当保载时间超过60 s时,裂纹扩展速率随时间呈线性比例增大,表明此时裂纹扩展行为与时间因素相关.     

30Cr1Mo1V转子钢的蠕变特性

对30Cr1Mo1V转子钢在540℃和565℃下进行了有中断的蠕变试验研究，应力范围为240-320MPa，得到了蠕变过程中损伤因子和蠕变寿命分数之间的关系。通过蠕变试验后试样维氏硬度的检测和蠕变过程中硬度对蠕变断裂性能的影响分析，提出了蠕变断裂Larson-Miller公式的硬度修正公式，并对其有效性进行了检验。结果表明：在Larson-Miller参数值大于18000时，修正值与实际值比较一致；而在小于该值时相差较大。此外，还研究了损伤和Larson-Miller数之间的关系。     

15Cr1Mo1V锻件套管热处理生产中常见问题的处理方法

主要针对汽轮机中１５Ｃｒ１Ｍｏ１Ｖ锻件管在热处理生产中出现的各种机械不合格现象进行了分析,提出了解决这些问题的具体措施,并应用于生产中,实践这些措施是正确、有效的。     

长期服役后高中压转子30Cr1Mo1V钢的性能研究

通过室温拉伸、高温拉伸和冲击等试验研究了经过长期服役后的高中压转子30Cr1Mo1V钢不同位置的性能变化,并分析了转子强度和韧性变化的原因.结果表明：转子服役温度高的部位碳化物的形貌、分布和大小均发生变化,贝氏体和铁素体中的碳化物析出、聚集或长大,而原奥氏体晶界和贝氏体与铁素体边界处碳化物析出增多,碳化物颗粒变得粗大;不同位置的拉伸性能差别不大,服役温度最高位置的拉伸强度最低,冲击韧性下降;不同部位总冲击能量的降低主要表现为裂纹形成能的降低,而裂纹扩展能区别很小;高中压转子30Cr1Mo1V钢服役时高温位置的韧脆性转变温度（FATT50）比低温位置明显升高.     

21/4Cr-1Mo钢焊后产生焊接裂纹的原因分析及其返修措施

针对 2 1 /4Cr-1Mo钢焊接后产生裂纹的原因进行了分析 ,结果表明 ,产生裂纹的主要原因是氢浓度过高而引起的氢致延迟裂纹 ,并根据实际的产品特点提出了合适的返修措施     

Effects of hydrogen on the interfacial reaction between Ti6Al4V alloy melt and Al2O3 ceramic shell

Effects of hydrogen on the interfacial reaction between Ti6Al4V (Ti64) alloy melt and Al₂O₃ ceramic shell were studied by arc-melting in H₂/Ar gaseous mixture. The thickness of interfacial reaction layer between Ti64 alloy melt and Al₂O₃ ceramic shell without hydrogenation is 80 μm. But the thickness of reaction layer can be reduced to 10 μm at a hydrogen partial pressure of 20 kPa, which is better than the thickness of interface layer between Ti64 alloy and widely used Y₂O₃ shells. At Ti64 casting surface, the content of β-soft ductile phase is increased and the width of both reaction zone and transition zone are reduced with the increase of hydrogen partial pressure, thus reduces the hardness and the element diffusion distance. Therefore, Hydrogen can effectively control the interfacial reaction in the process of titanium alloy investment casting, and Al₂O₃ ceramic will be a kind of very promising shell material.     

Effect of hydrogen on diffusion bonding of commercially pure titanium and hydrogenated Ti6Al4V alloys

The diffusion bonding of commercially pure titanium and hydrogenated Ti6Al4V alloys was carried out, and the effect of hydrogen was investigated by SEM, XRD, TEM and TG/DSC. The β_H phase increased with the hydrogen content increasing in hydrogenated alloys, and the δ titanium hydride and α′ martensite were found in high hydrogen content. The TG curves of hydrogenated alloys descended between 600 °C and 950 °C, and the DSC curves represented a large endothermic peak correspondingly. Moreover, some voids were observed at the diffusion bonding interface. The amount of voids decreased and diffusion bonding quality improved gradually with the increase of hydrogen content, which was attributed to the increase of soft β_H phase and release speed of hydrogen as well as the occurrence of more dehydrogenation reaction.     

Effect of hydrogen on the microstructure and mechanical properties of high temperature deformation of Ti6Al4V additive manufactured

The additive manufactured Ti6Al4V-xH titanium alloy was compressed at 600°C–750 °C on a Gleeble 3800 testing machine, and the compression rates were 1s⁻¹ and 0.01s⁻¹, respectively. The experimental results show that with the increase of hydrogen content, the flow stress of the alloy decreases firstly and then increases gradually. When the hydrogen content is 0.27 wt%, the flow stress of titanium alloy is the smallest. EBSD and TEM analysis were carried out and show that the α lamellar microstructure became larger at 0.27H, the corresponding flow stress also decreased, and slip bands appeared in the alloy. Dislocation slip was an important deformation mechanism of the alloy. When the hydrogen content continued to increase, the α phase in the alloy gradually decreased, and α″ appeared at 0.81H. Therefore, adding appropriate hydrogen can reduce the alloy flow stress and improve the performance of titanium alloy during hot deformation.     

30Cr2Ni4MoV低压转子焊补区域在役检查及结果评估

介绍了某600MW汽轮机低压转子靠背轮焊补区域服役8年间的在役检查情况.通过连续7次在役检查,对该区域的性能进行了评估.检查结果表明,焊补区域组织正常,各项性能满足设计要求,转子可以继续正常服役.