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RPC钢是一种具有超细的贝氏体组织和较好力学性能的新一代钢铁材料。激光焊接有很快的加热和冷却速度 ,热作用范围窄 ,在合适的工艺条件下可避免RPC钢HAZ的软化 ,激光焊接是高质量焊接RPC钢的方法之一。本文利用 4kWYAG激光对RPC钢焊接接头组织进行了实验研究 ,分析了在激光焊接工艺条件下焊接接头组织及其变化规律。实验结果表明 ,RPC钢激光焊接接头的主要组织是由板条状的贝氏体铁素体板条和板条间呈方向性分布的岛状的M -A组元组成的粒状贝氏体 ;随着热输入的增大 ,M -A组元的平均宽度、总量增大 ,M -A组元单位长度的数量减少 ,长条形M -A组元比例下降 ,而方块形M -A组元比例上升 ;焊接接头显微硬度随热输入的增大而减小 ,均高于母材 ,未出现明显的软化区。
RPC steel is a new generation of steel with ultra-fine bainitic structure and good mechanical properties. Laser welding has very fast heating and cooling rates, a narrow thermal range, and avoids the softening of the HAZ of RPC steel under appropriate process conditions. Laser welding is one of the most popular methods for welding RPC steel. In this paper, 4kWYAG laser was used to study the microstructure of the welded joints of RPC steel. The microstructure of the welded joints and its variation under the laser welding process were analyzed. The experimental results show that the main microstructure of laser welded joints of RPC steel is granular bainite consisting of lath - shaped bainitic ferrite lath and island - shaped M - A component distributed between the laths. With the increase of heat input, the average width and total amount of M-A component increased, the number of M-A component unit length decreased, the proportion of long M-A component decreased, while M-A The proportion of components increased; the microhardness of welded joints decreased with the increase of heat input, both higher than the base metal, no obvious softening zone did not appear.