水射流喷丸对渗碳钢表层组织与裂纹扩展性能的影响

Effect of water jet peening on microstructure and crack propagation of carburized steel

对低碳钢渗碳淬火试样进行表面水喷丸处理,研究水喷丸对渗层表面组织结构及其疲劳裂纹扩展速率的影响。结果表明:添加细玻璃丸的水喷丸处理能显著细化表层亚结构,提高小角度晶界密度,并为渗层带来有效的残余压应力。在300 MPa水压及600 mm/min扫描速率工艺下,可实现100μm左右深度,最高达1244 MPa的残余压应力,其表面粗糙度Ra=0.195μm。疲劳裂纹速率试验结果显示,经过水喷丸处理后裂纹扩展速率da/d N有增加的趋势,这主要是因为表面压应力形成,增加了心部拉应力,且表层的变形强化降低了裂纹尖端塑性区。

Effect of water jet peening on microstructure and fatigue crack growth rate of carburized layer was studied by water jet peening on the surface of carburized and quenched low carbon steel.The results show that water jet peening with fine glass beads can significantly refine the surface substructure and increase the density of small angle grain boundaries,and also brings effective residual compressive stress to the carburized layer.Under the condition of 300 MPa water pressure and 600 mm/min scanning rate,the residual compressive stress with a depth of about 100μm and a maximum of 1244 MPa can be achieved and the corresponding surface roughness Ra is 0.195μm.The results of fatigue crack rate test show that the crack growth rate da/d N has an increasing trend after water jet peening,which is mainly due to the formation of surface compressive stress and the increase of the tensile stress in the center,and the deformation strengthening of the surface layer reduces the plastic zone at the crack tip.