钨钼钇共渗强化层的回火硬度及红硬性

利用双层辉光等离子渗金属技术,在Q235钢表面分别进行钨钼钇共渗与钨钼共渗,形成均匀致密合金扩散层;共渗后,将两种试样分别在960℃、980℃、1020℃下进行8h渗碳及淬火,并在200℃低温回火1h。之后将两者在1 020℃渗碳及淬火,并分别进行200～700℃回火。采用显微硬度仪检测其表面硬度,采用光学显微镜、SEM及EDS分别对渗层进行金相组织及成分分析。结果表明:其回火特征与冶金高速钢类似,在500℃时出现"二次硬化"现象,回火硬度达到峰值,且前者高于后者。将经过1 020℃渗碳淬火后的两种试样在600℃下保温1h后空冷,重复4次后,前者与后者的表面硬度最大值分别达到750 HV0.05、650HV0.05。

Tempering Hardness and Red-hardness of Strengthen-layer after Plasma W-Mo-Y Surface Alloying Process

A uniform dense alloying-diffusion-layer on the surface of Q235 steel was formed by the double glow plasma W-Mo-Y surface alloying process and W-Mo surface alloying process respectively in order to form.Then they were conducted low temperature tempering process at 200 ℃ for 1 h after carburizing and quenching process at 960 ℃,980 ℃ and 1 020 ℃ for 8 h respectively.Afterwards two surface alloys were carburized and quenched at 1 020 ℃,and then tempered at 200~700 ℃ respectively.The micro-hardness and its distribution,microstructure and content distribution of alloying layer were analyzed respectively by microhardness tester,metalloscope,SEM and EDS.The results is showed as follows: the tempering behavior of the layers is the same as that of the metallurgy high speed steel.The secondary hardening occures at 500 ℃,when the tempering hardness reaches the maximum,higher than that of W-Mo surface alloy.When two surface alloys that are conducted by carburizing and quenching process at 1 020 ℃ are air cooled after thermal insulating at 600℃ for 1 h,their maximum hardness values become 750 HV0.05 and 650 HV0.05 respectively after being repeated for 4 times.