AISI316L奥氏体不锈钢在摸拟人体组织液中腐蚀疲劳裂纹萌生的初步研究

AISI316L奥氏体不锈钢是较常用的金属植入材料之一.但在临床应用中,由它制成的植入物特别是全髋关节,常因腐蚀疲劳破断而失效.本文对316L不锈钢在Hank’s溶液中的腐蚀疲劳裂纹萌生机理进行了初步研究.结果发现,在Hank’s溶液中,自然钝化的316L不锈钢在稳定钝化态下,裂纹的萌生是由交变应力引起的微观塑性变形和Hank’s溶液交互作用的结果;在有点蚀产生的非钝化态下,裂纹的萌生是点蚀和腐蚀疲劳相叠加的结果.316L不锈钢经离子氮化表面处理后,提高了在Hank’s溶液中的抗点蚀能力,但在外加腐蚀电位的苛刻条件下,困氮化层发生晶间腐蚀和脱落而加速了裂纹的萌生

PRELIMINARY STUDIES ON CFCI MECHANISM OF AISI 316L ASS IN HANK'S PHYSIOLOGICAL FLUID

AISI 316L austenitic stainless steel is one of metal implantation materials available. In clinic, 316L-made implants, especially total hip joints often fail in service due to corrosion fatigue fracture. This paper has preliminarily studied the corrosion fatigue crack initiation (CFCI) mechanism of 316L in Hank's solution. In stable passive state,the CFCI mechanism of 316L can be described as synergitic interaction between Hank's solution and micro-plastic deformation induced by alternating stress;in unstanle passive state,CFCI is accelerated by the superposition of corrosion fatigue and pitting. Ion nitriding surface treatment improves the pitting resistance of 316L in Hank's solution,but it facilitates crack initiation under crucial applied corrosion potential owing to the intergranular corrosion and exfoliation of the nitrided layer.