20SiMn钢冲蚀和空蚀的失效行为研究

Failure Behavior of 20SiMn Steel in Erosion and Cavitation Erosion Processes

用CMS 12 0旋臂式真空冲蚀试验机和KS 6 0振动空蚀磁致伸缩仪对 2 0SiMn钢 90°攻角冲蚀和空蚀进行了试验研究 .结果表明 :2 0SiMn钢冲蚀分为孕育期、增重期和稳定期 3个阶段 ;空蚀由孕育期、急剧上升期、衰减期和稳定期 4个阶段组成 ;冲蚀、空蚀裂纹主要沿晶界萌生和扩展 ,失效机制是因局部微区机械力作用造成沿晶断裂和晶内蚀坑 ;晶粒脱落是空蚀的重要失效方式之一 .

Using a CMS 120 whirling arm vacuum erosion rig and KS 60 vibratory cavitation magnetostrictive instrument, tests on erosion at impact angle of 90 degrees and cavitation erosion for the 20SiMn (0 2%C 0 6%Si Mn) steel were carried out. The results show that the erosion process of the steel is divided into three stages incubation, mass increase and steady periods; and its cavitation erosion process consists of four stages incubation, accumulation, attenuation and stationary periods. Cracks principally initiate and propagate along crystal boundaries both in erosion and cavitation erosion processes, and the failure mechanisms are intergranular failure and etching pits in grain interior due to local microzone mechanical effect. Crystal grain's peeling off is one of the major failure modes in cavitation erosion process.