Fe314合金激光熔覆层的应力分布规律

研究熔覆层应力分布规律对控制裂纹萌生及提高抗疲劳和抗腐蚀等性能至关重要。利用Nd∶YAG固体激光器在45钢基体表面制备了厚度约5mm的Fe314激光熔覆层,利用X射线衍射应力测定仪对熔覆层表层不同位置及其沿深度方向的应力分布情况进行分析,利用金相显微镜观察熔覆层显微组织,利用维氏硬度计对熔覆层硬度分布规律进行分析。研究结果表明:平行激光扫描方向的熔覆层表面应力最大值出现在熔覆层边缘,约为290MPa;垂直激光扫描方向的表面应力最大值出现在熔覆层中心,约为230MPa,由中心向边缘递减,并逐渐由拉应力转变为压应力;深度方向上,平行激光扫描方向的应力随熔覆层深度增加先保持平稳后不断增大;垂直激光扫描方向的应力随熔覆层深度增加而增大;应力分布主要受热累积效应影响,熔覆层具有与热累积效应对应的金相结构,熔覆层硬度范围为380～450HV0.3,略高于基体。

The Law of Stress Distribution of the Laser Cladding Layer of Fe314 Alloy

Research on stress distribution of the laser cladding layer was important to control its crack initiation and improve its wearresistant and corrosionresistant properties. Laser cladding layer of Fe314 alloy with the thickness of 5 mm was prepared by YAG solid-state laser, the stress distribution at different cladding layer surface positions and along the depth of the cladding layer were analyzed using X-ray diffraction determination, the metallographic microstructure was observed using metallurgical microscope, and the hardness distribution was studied using Vickers hardness tester. The maximum stress along the direction of laser scanning on the surface was about 290 MPa near the edge. The stress perpendicular to the direction of laser scanning was in decline form the center to the edge, its maximum in the centre of the cladding layer surface was about 230 MPa, and it was found transferred from tensile stress to compressive stress. With increasing depth, the stress along to the direction of laser scanning was found stable first and then increased, and the stress perpendicular to the direction of laser scanning increased. The stress distribution was mainly influenced by thermal cumulative effect, the cladding layer had metallographic structure which is in accordance with thermal cumulative effect, and the hardness of the cladding layer was 380~450 HV_0.3, a little higher than the substrate.