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标题：Microstructure and Hardness of Cold Forged 42CrMo4 Steel Hollow Component with the Outer Flange
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作者：Mirosław Szala ; Grzegorz Winiarski ; Tomasz Adam Bulzak 等
期刊名称：Advances in Science and Technology Research Journal
印刷版ISSN：2080-4075
电子版ISSN：2299-8624
出版年度：2022
卷号：16
期号：4
页码：201-210
DOI：10.12913/22998624/152790
语种：English
出版社：Society of Polish Mechanical Engineers and Technicians
摘要：For decades, steel has been a crucial structural material. Mainly low-alloy steel grade ISO 42CrMo4 is utilized for manufacturing forgings. This paper investigates the microstructure and hardness development of the 42CrMo4 steel hollow component with an outer flange. The component has been formed via cold forging in combination with extrusion and upsetting technologies. Prior to forming, the workpiece was annealed to obtain hardness at the level of 181±9 HV0.3. The FEM analysis reveals the areas that undergo higher stress and strain. The flow lines macrostructure and microstructure of hollow parts were investigated using light optical microscopy (LOM) and scanning electron microscopy (SEM) equipped with EDS. Vickers hardness allows identifying the work hardening of the crucial element areas. The microstructure consists of ferrite matrix and semi-globular carbides. Laboratory studies confirm appropriate flow lines arrangement, which corresponds well to those shown by FEM computer simulations. The highest hardness at the level of 293±7 HV0.3 was identified in the flange area, where the material shows a higher distribution of effective strain revealed by FEM. Cold metal forming results in work-hardening of the steel. The work hardening ranges up to 1.62 of the initial 42CrMo4 steel hardness. The metal forming process did not affect the microstructural uniformity of the flanged hollow part. The final outer flange component presents high quality and is free from plastic deformation nonuniformities.
关键词：microstructure;hardness;strain hardening;steel;extrusion;metal forming;upsetting;FEM