激光熔覆制备楔块高硬度层的工艺方法研究

Study on the Process of Wedge High Hardness Layer by Laser Cladding

摘要: 楔块是电梯安全钳中重要的零部件，实际工况要求楔块表面具有高硬度的特点。本文以Q235钢为基体，以含WC的镍基合金粉末为熔覆材料，采用激光熔覆技术制备了大面积的熔覆层。采用扫描电镜、能谱仪对熔覆层进行了微观组织的分析，测试了熔覆层、结合处以及基体的硬度。研究表明以Q235钢为基体时，在激光功率1200 W至2000 W之间，扫描速度在2 mm/s左右时能获得表面质量良好的熔覆层。由于涂层中不同部位的成分、温度分布及冷速不同，组织中析出了多种尺寸及形态的WC颗粒，基体组织梯度特征明显，实现了涂层与基体间的冶金结合。熔覆层表面硬度高达1100 HV以上。

Abstract: Wedge is an important part of elevator safety gear, the surface should have high hardness as the demand of working condition. Layers are prepared by laser cladding, and the matrix is Q235 steel, cladding powder is Ni base alloy with WC. The scanning electronic microscope and energy disper-sive spectrometer are applied to analyze microstructures and element of particle phase surface. The hardness of layer is also tested. It shows that when laser power is controlled at 1200 W to 2000 W and scanning speed is about 2 mm/s, good quality layer is manufactured. Because of the different composition, temperature and cooling rate, WC particles with various sizes and shapes are precipitated in the layer. The microstructure of the matrix shows an obvious gradient. The layer and matrix are metallurgically bonded. The hardness of layer is above 1100 HV.