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借助X射线衍射、显微组织、维氏硬度和切环残余应力分析研究了304不锈钢壳各道次变薄拉深制件的组织结构与性能。结果表明:随着304不锈钢壳变形变薄量的增加,直壁形变诱发α’马氏体转变量增加,变薄拉深后最终α’马氏体相占主导地位,无hcp结构ε马氏体的形成;显微组织呈现出晶粒越细长,板条状马氏体越多,在第三道变薄拉深后板条马氏体呈现一定的方向性,晶粒被拉长为纤维状组织;硬度从323.7 HV增加到400.8 HV;从落料拉深到第一道变薄拉深制件直壁的残余应力降低了48.5%,但后续的第二道和第三道变薄拉深后,其残余应力增幅分别为23%、16.7%。随着拉深成形的进行,304不锈钢壳强度增加,塑性降低,切向残余应力也逐渐增大,可能出现掉底、纵向开裂等缺陷,因此工艺设计时应严格控制变形量和拉深道次。
The microstructure and properties of 304 stainless steel shell were studied by X-ray diffraction, microstructure, Vickers hardness and shear stress analysis. The results show that the α ’martensitic transformation induced by straight wall deformation increases with the increase of deformation and thinning of 304 stainless steel shell, and the final α’ martensite phase dominates after thinning and deep drawing without hcp structure The formation of the body; the microstructure shows the more slender grains, the lath martensite more, after the third thinning deepened lath Martensite shows a certain direction, the grain is elongated Fibrous structure; the hardness increased from 323.7 HV to 400.8 HV; the residual stress of the straight wall from the blanking depth to the first thinned part decreased by 48.5%, but the subsequent second and third thinning After drawing, the residual stress increases were 23%, 16.7%. With the development of deep drawing, the strength of 304 stainless steel shell increases, the plasticity decreases, the tangential residual stress also gradually increases, there may be defects such as falling bottom and longitudinal cracking, so the process design should strictly control the deformation and drawing times .