激光强化参数对40Cr钢表面组织及摩擦性能影响的研究

采用CO2横流式激光器对40Cr材料进行表面强化处理研究;使用S-360型扫描电镜观察激光硬化区金相组织及成分并观察金属表面磨损形貌;采用CHX-1超显微硬度计测量激光强化区断面的显微硬度;然后在MPX-2000盘销式摩擦磨损实验机上进行干摩擦和油润滑实验。结果表明:激光参数对表面硬度和硬化层深度有很大影响,较大的功率可使奥氏体转变充分而获得更多的马氏体,激光扫描速度越快,功率越大,显微硬度越高,硬化层越深;少量针状马氏体组织化引起表层强化,经激光硬化的表面其耐磨性可大大提高;40Cr在干摩擦条件下的平均磨损量是润滑时的5倍,40Cr和20MnSiV的磨损主要以磨粒磨损为主,同时也有粘着磨损。

Study on Effect of Laser Parameters on Surface Hardening Microstructure and Wear of 40Cr Steel

Transformation hardening on 40Cr steel surface with CO_2 laser was investigated.The microstructures and phase compositions as well as wear surface of laser transformation hardening zone were investigated with S-360 scanning electron microscope.Microhardness of laser hardening zone were measured with CHX-1 microhardness tester and dry wear and oil lubrication experiments were done in pin-on-disc fretted wear machine of MPX-2000 model.Experimental results show that the surface hardness and harden depth of material is greatly influences by laser processing parameters.The surface austenite phase is transformed in martensite phase under more laser power.The more hardness and depth are obtained under more laser power and more quickly scan speed conditions.Surface hardness is caused by needle martensite microstructures.The laser treated surface wear resistance is greatly improved,and average wear ratio of 40Cr steel under dry friction condition is 5 times under oil lubrication condition.Surface wear of 40Cr and 20MnSiV steel is caused by abrasive and adherence.