离子碳氮共渗扩散期富化气浓度对渗层的影响

对18CrMnTi和20Cr2Ni钢进行了强渗／扩散时间为3：3的离子碳氮共渗试验,扩散阶段分别通入不同浓度的丙烷。通过光学显微镜和显微硬度计对扩散期不同丙烷浓度下渗层的金相组织和硬度分布进行了对比分析。结果表明,扩散期的丙烷浓度对渗层产生了显著影响。丙烷浓度太低,渗层表面严重脱碳,丙烷浓度太高,渗层表面将形成大量的碳氮化物,并在次表层出现硬度的低谷。     

塑料模具钢及真空碳氮共渗热处理

介绍了常用的塑料模具钢及其相应的热处理工艺,并试验了碳素钢及P20(3Cr2Mo)钢制塑料模具的真空碳氮共渗工艺.结果表明碳素钢及P20钢制塑料模具经真空碳氮共渗油淬火处理后,淬火硬度值可提高至62 HRC以上,耐磨性增加,有助于提高模具的使用寿命.     

Duplex Surface Treatment of Pre-Electroplating and Pulsed Nanocrystalline Plasma Electrolytic Carbonitriding of Mild Steel

Recently, new duplex surface treatments involving the use of pre-electroplating and pulsed plasma electrolytic nitrocarburizing (PPEN/C) have led to the possibility of using this material for applications usually typical for tool steels. In this work, we present results concerning the duplex treatment of pre-electroplating of Cr and PPEN/C of AISI 1020 mild steel. The samples were electroplated in a plating bath. After electroplating, the samples were nitrocarburized. The effects of time and applied voltage of PPEN/C process were discussed. The samples were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), and microhardness testing. Electroplated layers of up to 100 μm were obtained. The subsequent PPEN/C increased the surface hardness to 1200 HV_0.2 due to the formation of nitrides and carbides. Decreasing the size of nanocrystalline carbonitrides will lead to improvement of their wear resistance significantly.     

CrWMn钢制滚丝模热处理工艺改进

CrWMn钢制滚丝模采用碳氮共渗再进行螺纹渗硼的复合渗强化工艺后,滚丝模表面共渗层深度达0.3mm,共渗层表面硬度高于碳氮共渗强化表面硬度,取代了氰化盐浴渗碳工艺,保护了环境。新工艺已应用于工业生产,滚丝模平均使用寿命达到了120万件,取得了较好的经济效益和社会效益。     

航空发动机轴承钢高温碳氮共渗的渗层组织与性能

航空发动机轴承用Ｍ５０ＮｉＬ钢高温（９００～９２０℃）碳氮共渗,可获得均匀细小的淬火、回火组织,其疲劳裂纹扩展抗力和高温硬度显著高于Ｍ５０钢。分析认为,疲劳裂纹沿渗层的扩展行为与残余奥氏体的诱发裂纹闭合效应,残余压应力,以及渗层塑性、韧性对断裂机制的影响有关;渗层高温硬度的提高则是马氏体回火相析出发生改变的结果。     

钛铝基合金离子碳氮共渗及其耐磨性的研究

为提高TiAl基合金的耐磨性及抗高温氧化性,利用渗氮在TiAl基合金表面形成氮化物,以提高耐磨性;渗碳形成致密且与基体结合牢固的碳化物层,提高抗高温、抗氧化性;将二者结合,采用辉光离子碳氮共渗的方法,研究了渗层的相结构组成、不同工艺参数对TiAl基合金离子碳氮共渗后渗层厚度以及表面硬度和耐磨性的影响.结果表明:TiAl基合金共渗层是由碳氮化合物层与过渡层组成的复合相结构;随共渗温度的升高和时间的延长,渗层厚度增加;与未经共渗处理的试样相比,表面硬度及耐磨性显著提高.X射线衍射结果显示,渗层主要由TiC,TiN,AlTi3,Al2O3等组成.