Kluczyński Janusz, Jasik Katarzyna, Łuszczek Jakub, Pokropek Jakub
Institute of Robots and Machine Design, Faculty of Mechanical Engineering, Military University of Technology, 00-908 Warsaw, Poland.
Materials (Basel). 2025 Aug 1;18(15):3623. doi: 10.3390/ma18153623.
This article provides a comprehensive overview of recent studies concerning laser heat treatment (LHT) of structural and tool steels, with particular attention to the 21NiCrMo2 steel used for carburized gear wheels. Analysis includes the influence of critical laser processing conditions-including power output, motion speed, spot size, and focusing distance-on surface microhardness, hardening depth, and microstructure development. The findings indicate that the energy density is the dominant factor that affects the outcomes of LHT. Optimal results, in the form of a high surface microhardness and a sufficient depth of hardening, were achieved within the energy density range of 80-130 J/mm, allowing for martensitic transformation while avoiding defects such as melting or cracking. At densities below 50 J/mm, incomplete hardening occurred with minimal microhardness improvement. On the contrary, densities exceeding 150-180 J/mm caused surface overheating and degradation. For carburized 21NiCrMo2 steel, the most effective parameters included 450-1050 W laser power, 1.7-2.5 mm/s scanning speed, and 2.0-2.3 mm beam diameter. The review confirms that process control through energy-based parameters allows for reliable prediction and optimization of LHT for industrial applications, particularly in components exposed to cyclic loads.
本文全面概述了近期关于结构钢和工具钢激光热处理（LHT）的研究，特别关注用于渗碳齿轮的21NiCrMo2钢。分析包括关键激光加工条件（包括功率输出、运动速度、光斑尺寸和聚焦距离）对表面显微硬度、硬化深度和微观结构发展的影响。研究结果表明，能量密度是影响激光热处理结果的主导因素。在80 - 130 J/mm的能量密度范围内可实现最佳结果，即高表面显微硬度和足够的硬化深度，能实现马氏体转变同时避免诸如熔化或开裂等缺陷。在密度低于50 J/mm时，会发生不完全硬化，显微硬度提高极少。相反，密度超过150 - 180 J/mm会导致表面过热和性能退化。对于渗碳的21NiCrMo2钢，最有效的参数包括450 - 1050 W激光功率、1.7 - 2.5 mm/s扫描速度和2.0 - 2.3 mm光束直径。该综述证实，通过基于能量的参数进行过程控制能够可靠地预测和优化激光热处理在工业应用中的效果，特别是在承受循环载荷的部件中。
