Laser Surface Hardening of Tool Steels—Experimental and Numerical Analysis
Laser Surface Hardening of Tool Steels—Experimental and Numerical Analysis作者机构：Manufacturing Technology Department Central Metallurgical R & D Institute Cairo Egypt Mechanical Engineering Department Faculty of Engineering Helwan University Helwan Egypt. Spare Parts Sector Egyptian Iron and Steel Company Helwan Egypt
出 版 物：《Journal of Surface Engineered Materials and Advanced Technology》 (表面工程材料与先进技术期刊（英文）)
年 卷 期：2013年第3卷第2期
页 面：146-153页
学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学]
主 题：High Speed Tool Steels Laser Surface Hardening Ashby and Easterling Heat Transfer Equations Design Expert Software Laser Processing Charts
摘 要：This research work is focused on both experimental and numerical analysis of laser surface hardening of AISI M2 high speed tool steel. Experimental analysis aims at clarifying effect of different laser processing parameters on properties and performance of laser surface treated specimens. Numerical analysis is concerned with analytical approaches that provide efficient tools for estimation of surface temperature, surface hardness and hardened depth as a function of laser surface hardening parameters. Results indicated that optimization of laser processing parameters including laser power, laser spot size and processing speed combination is of considerable importance for achieving maximum surface hardness and deepest hardened zone. In this concern, higher laser power, larger spot size and lower processing speed are more efficient. Hardened zone with 1.25 mm depth and 996 HV surface hardness was obtained using 1800 W laser power, 4 mm laser spot size and 0.5 m/min laser processing speed. The obtained maximum hardness of laser surface treated specimen is 23% higher than that of conventionally heat treated specimen. This in turn has resulted in 30% increase in wear resistance of laser surface treated specimen. Numerical analysis has been carried out for calculation of temperature gradient and cooling rate based on Ashby and Easterling equations. Then, surface hardness and hardened depth have been numerically estimated based on available Design-Expert software. Numerical results indicated that cooling rate of laser surface treated specimen is high enough to be beyond the nose of the CCT diagram of the used steel that in turn resulted in a hard/martensitic structure. Numerically estimated values of surface temperature, surface hardness and hardened depth as a function of laser processing parameters are in a good agreement with experimental results. Laser processing charts indicating expected values of surface temperature, surface hardness and hardened depth as a function of different wider range of laser processing parameters are proposed.
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