Hardness, microstructure and residual stresses induced on the engineered steel surface have a significant effect on the manufacturing process and the life time of the components. In the present work, these are analysed on laser-treated layer obtained on 100Cr6 bearing steel surface involving different thermal processing conditions. Prior to laser surface hardening treatment, the steel was spheroidized and hardened and tempered with resulting microstructure comprising of globular carbides in the matrix of martensite and retained austenite. A 20-mm wide diode laser beam was employed with a fixed peak laser power in both continuous wave and pulsed wave modes. Additionally, the treatment was carried out with an arrangement to induce fluid contact beneath the workpiece to enhance the heat transfer coefficient. Results indicated maximum improvement in hardness (1050–1100 HV) and compressive residual stress (−630 ± 20 MPa) with retention of core properties on treated surface processed with pulsed-wave mode under fluid contact owing to formation of refined microstructure constituting refined globular carbides (alloy nano-carbides) and retained austenite in martensite matrix. The extent of increase in compressive residual stress and treated layer microhardness was found to depend on the extent of martensite refinement and alloy nano-carbides dispersed in the matrix. Sliding wear tests conducted in both unlubricated and lubricated conditions indicated gradual improvement in wear resistance of the treated surface with increase in cooling rate governed by the thermal processing condition employed with conventionally hardened and tempered one being lowest and laser processed with pulsed wave mode under fluid contact being highest. Apparently, the laser treated surface processed with pulsed-wave mode under fluid contact exhibited reduction in friction coefficient with retention of core properties as compared to untreated counterpart.

在工程钢表面上引起的硬度，微观结构和残余应力对零件的制造过程和使用寿命有重要影响。在本工作中，将对涉及不同热处理条件的在100Cr6轴承钢表面上获得的激光处理层进行分析。在进行激光表面硬化处理之前，对钢进行球化，硬化和回火处理，得到的显微组织包括在马氏体和残余奥氏体中的球状碳化物。在连续波和脉冲波模式下，使用20毫米宽的二极管激光束，并具有固定的峰值激光功率。另外，该处理以使流体在工件下方接触以提高热传递系数的布置进行。结果表明，由于形成了细化的球状碳化物而形成了细化的微观结构，在流体接触下以脉冲波模式处理的被处理表面上，保留了核心特性，从而最大程度地提高了硬度（1050–1100 HV）和压缩残余应力（-630±20 MPa） （合金纳米碳化物）和残留奥氏体在马氏体基体中。发现压缩残余应力和处理层显微硬度的增加程度取决于马氏体细化程度和分散在基体中的合金纳米碳化物的程度。在非润滑和润滑条件下进行的滑动磨损测试表明，随着冷却速率的增加，处理过的表面的耐磨性逐渐提高，这取决于热处理条件，其中常规淬火和回火的热处理条件最低，并且在流体接触下以脉冲波模式进行激光加工最高。显然，与未处理的对应物相比，在流体接触下以脉冲波模式处理的激光处理表面表现出摩擦系数的减小，并保留了芯的性质。