纯钛空化水喷丸表面强化及空蚀损伤

Water Cavitation Peening-induced Surface Hardening and Cavitation Damage of Pure Titanium

采用空化水喷丸技术对工业纯钛表面进行强化处理,研究表面强化机理及空蚀过程。通过显微硬度仪、光学显微镜对空化水喷丸后试样的表面硬度、显微组织、表面形貌和表面粗糙度进行分析。结果表明:具有密排六方结构的纯钛经过水喷丸处理后,试样表面强化层有大量的变形孪晶和次生孪晶。试样表面硬度最大可提高118HV0.2,而表面粗糙度Ra仅为2.1μm,这说明空化水喷丸对纯钛表面的强化效果显著,而且表面损伤较小。在30MPa水喷丸压力下,纯钛水喷丸最佳时间为80min,强化效果最好。水喷丸后试样的强化表面可分为A、B和C 3个区域。A区表面空蚀最严重,空蚀坑小而密集,B区和C区因受到二次射流的作用,空蚀坑具有明显的方向性。

Water cavitation peening（WCP） was used to strengthen the surface of pure titanium.The mechanism of the WCP treatment and cavitation erosion process on pure titanium surface was investigated. The surface hardness, microstructure, morphologies and surface roughness of the test specimens enhanced by WCP were analyzed by optical microscope and microhardness tester. The results indicate that twin plays an important role in the plastic deformation of hexagonal closepacked （HCP） structured metal materials. The surface hardness can be improved 118 HV0.2, while the surface roughness is only 2.1 μm, which indicate that the surface hardening effect of WCP is obvious and the damage to the surface is very small. The best strengthening effect can be obtained when the WCP pressure is 30 MPa, and the optimal time of WCP for titanium is 80 min. The strengthening morphologies of WCP can be separated into three regions： A,B and C. The damage in region A is the most serious, and the cavitation is small and dense. The cavitations of regions B and C on the surface have inevitable directional properties due to the effect of the secondary jet.