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采用淹没式空化水射流方法对304不锈钢表面进行不同压力和时间的空化水射流处理,用扫描电子显微镜原位跟踪观察处理后的试样表面形貌,研究其空蚀损伤过程及空蚀机理,并对表层组织和304不锈钢变形机理进行了探讨。结果得出,根据损伤程度和作用机理的不同,空蚀损伤区从中心到外围可以分为射流冲击区、过渡区和紊流区三个区,其中射流冲击区损伤最严重,紊流区次之,过渡区最弱。当射流压力为35 MPa、处理40 min时,射流冲击区损伤速度加快,并且呈现明显的疲劳损伤特征,滑移带和晶界处疲劳裂纹萌生和扩展是导致该区损伤剥落的重要原因;在横截面金相组织中,过渡区和紊流区出现比射流冲击区更深的形变孪晶层,且紊流区形变孪晶层厚度达140μm;在本实验条件下304不锈钢变形方式为滑移为主,孪生为辅。试样在空化水射流的作用下有两种空蚀破坏机理,即交变载荷下疲劳破坏,以及塑性变形、颈缩和剥落导致的弧坑。
The submerged cavitation water jet method was used to treat the cavitation water jet of 304 stainless steel at different pressures and times. The surface morphology of the treated sample was observed with a scanning electron microscope in situ, and the cavitation damage and cavitation erosion were studied Mechanism, and the surface texture and 304 stainless steel deformation mechanism were discussed. The results show that, according to the degree of damage and the mechanism of action, cavitations damage zone from the center to the periphery can be divided into jet impact zone, transition zone and turbulence zone three areas, including jet impact zone damage the most serious, The transition zone is the weakest. When the jet pressure is 35 MPa and the treatment time is 40 min, the damage velocity in the jet impact zone accelerates, and shows obvious fatigue damage characteristics. The initiation and propagation of fatigue cracks at the slip band and grain boundary are the important reasons for the flaking of this zone. In the cross-section of the microstructure, the deformation zone and the turbulence zone appear deeper than the jet impact zone twinned layer, and turbulence zone deformation twin layer thickness of 140μm; 304 stainless steel in this experimental conditions for the deformation of the slip Lord, twin supplemented. Under the action of cavitating water jets, there are two kinds of cavitation damage mechanism, namely fatigue failure under alternating load, as well as craters caused by plastic deformation, necking and spalling.