Laser Surface Hardening of Austenitic Stainless Steel

摘要

For the purpose of studying the possibilities of increasing the wear resistance, keeping a high level of corrosion strength, austenitic stainless steel specimens mainly containing 19.2percentCr and 9.4percentNi were two-step surface alloyed using added materials (AMs) with hard particles of carbides (WC), nitrides (TiN), and borides (TiB_2). The simultaneous melting of AM and surface layer was performed by a CO_2 continuous wave laser on a numerically controlled X-Y table. On these specimens, the microstructural characteristics, microhardness, and depth of the molten zone were determined, which allowed definition of the AM with the best hardening effect. The research continued by two-step laser surface alloying of the same base material with different effective AM quantities. The specimens were processed by continuous wave laser radiation, by multiple-pass with 35percent overlap. The alloyed layers were described by light optical microscopy, x-ray diffractometry, flash spectrometry, and hardness measurement The conditions to obtain compact surface layers with 2.5 to 3 times higher hardness than the base material were determined.