核电阀门旁轴送丝激光熔覆司太立合金工艺研究

Research on Laser Cladding Process of Stellite Alloy for Nuclear Power Valves with Side-Axial Wire Feeding

摘要: 针对核级阀门密封面原位修复需求，本文采用旁轴送丝激光熔覆工艺在A42AP钢表面制备Stellite 6合金熔覆层，系统研究扫描速度对熔覆层成形质量及力学性能的影响规律。通过着色渗透检测、截面金相分析与显微硬度测试，评价不同热输入条件下的熔覆层缺陷敏感性、几何精度及截面硬度分布特征。结果表明：三种扫描速度下均可获得表面成形良好、无裂纹未熔合等缺陷的熔覆层；随扫描速度提升，线能量密度降低导致熔池存在时间缩短，熔覆层厚度由3190 ± 57 μm递减至1632 ± 85 μm，且厚度波动幅度增大；熔覆层硬度均显著高于基体，但随扫描速度增加呈下降趋势且均匀性劣化，高速扫描下热输入不足导致的层间重熔不充分及冷却速率过快，是硬度离散度增大的主要原因。

Abstract: To meet the in-situ repair requirements of nuclear valve sealing surfaces, Stellite 6 alloy coating is deposited on A42AP steel substrates via side-axial wire-feeding laser cladding. The effects of scanning speed on forming quality and mechanical properties are systematically investigated. Defect sensitivity, geometric accuracy, and cross-sectional hardness distribution are evaluated through dye penetrant testing, metallographic analysis, and microhardness measurements. Results indicate that no cracks or lack of fusion are found in the coatings without under all three scanning speeds. As the scanning speed increases, the linear energy density decreases, leading to a shortened molten pool duration. Consequently, the thickness of the cladding layer decreases from 3190 ± 57 μm to 1632 ± 85 μm. The hardness of the cladding layer is significantly higher than that of the substrate, but it tends to decrease and its uniformity deteriorates with increasing scanning speed. The insufficient heat input during high-speed scanning leads to inadequate interlayer remelting and an excessively fast cooling rate, which are the main reasons for the increased hardness dispersion.