超声冲击处理S30408表面硬度研究

Research on Surface Hardness of S30408 by Ultrasonic Impact Treatment

采用显微硬度测试以及纳米压痕技术测量超声冲击处理奥氏体不锈钢S30408硬度沿厚度方向的变化,分析超声冲击处理后材料表面力学性能的变化。结果表明:表面硬度和硬化层厚度的增加在冲击时间达到180 s后趋于平缓;处理后,S30408表层的弹性模量约为230 GPa,与未受处理影响区域相比,提高了28%;S30408沿厚度方向的纳米硬度值线性增大,弹性恢复系数线性降低;S30408表面产生剧烈的塑性变形,降低了微孔洞的数量,从而提高了材料的局部弹性模量,形成了梯度纳米结构表层;获得的表层纳米晶粒符合H-P关系,参数值为:H_(0)=212.16,K_(h)=1 827.5。

The microhardness test and nanoindentation technique were used to measure the change of hardness along the thickness direction of ultrasonic shock treated austenitic stainless steel S30408,and the change of surface mechanical properties after ultrasonic shock treatment was analyzed.The results showed that the increase in surface hardness and hardened layer thickness tended to be flat after the impact time reaches 180 s;after treatment,the elastic modulus of the surface layer of S30408 was about 230 GPa,which was 28%higher than that of the unaffected area.The nano hardness value of S30408 along the thickness direction increased linearly,and the elastic recovery coefficient linearly decreased.The obtained surface nanocrystalline grains conform to the H-P relationship,and the parameter values were:H_(0)=212.16,K_(h)=1827.5.