H13钢自保护膏剂稀土渗硼工艺优化

目前鲜见针对H13钢铁稀土渗硼的工艺优化研究。为此,采用自保护膏剂对H13钢进行稀土渗硼试验,运用正交试验法考察了渗硼时间、渗硼温度、稀土含量对渗层厚度、显微组织、显微硬度的影响,从而优选渗硼工艺。结果表明:渗层厚度随着稀土含量的增大先增加后减少,渗硼温度和渗硼时间的增加均可提高渗层厚度。由此得到最优的稀土渗硼工艺参数为:渗硼温度950℃、渗硼时间4 h、稀土含量4%,在此最优工艺下稀土渗硼层厚度达92.1μm,比无稀土渗硼提高约70%;其中,稀土渗硼的高硬度层(大于800 HV)厚度达75μm,比无稀土渗硼提高约1倍,并且显微组织更为致密均匀,渗硼层与基体结合更为紧密。

Optimization on Rare Earth Self-Protective Pasty Boronizing Process for H13 Steel

The experiment of rare earth boronizing for H13 steel was carried out by using the self-protective paste. In the experiment,orthogonal test method was used to explore the effect of boronizing time,temperature and rare earth content on the thickness,microstructure and microhardness of the layer,and the boronizing process was optimized. Results showed that the thickness of the layer increased and then decreased with the increase of rare earth content,and the increase of boronizing temperature and boronizing time could increase the thickness of the layer.The optimal process parameters of the rare earth boronizing were as follows: boronizing temperature 950 ℃,boronizing time 4 h,rare earth content 4%. The rare earth boronized layer had a thickness of 92.1 μm,which was about 70% higher than that of rare earth-free boronizing.The rare earth boronized high hardness layer( greater than 800 HV) had a thickness of 75 μm,which was about 1 time higher than that of rare earth-free boronizing. Moreover,the microstructure was denser and uniform,and the boronized layer was more closely bonded to the matrix.