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采用15kW高功率激光复合焊接船用低合金高强钢T型接头构件。测定了接头截面的显微硬度,通过光学显微镜、扫描电镜和透射电镜分析了焊缝微观组织。结果表明:焊接接头没有气孔、裂纹等缺陷;焊缝和热影响区显微硬度均高于母材,焊缝显微硬度最高为290HV;焊缝组织主要为细条状的粒状贝氏体和少量的M-A组元。贝氏体铁素体为细条状的铁素体,晶粒细小,晶界密度高。Cu、Ti等微合金元素形成的碳化物沉淀强化相分布于贝氏体铁素体内。细条状的粒状贝氏体组织的晶粒细化及其微合金碳化物(Cu,Ti)xCy的沉淀强化使得焊缝强度高于母材。
Using 15kW high-power laser composite welding low-alloy high-strength steel T-joint components. The microhardness of the joint section was measured. The microstructure of the weld seam was analyzed by optical microscope, scanning electron microscope and transmission electron microscope. The results show that the welded joints have no defects such as pores and cracks. The microhardness of the weld and the heat affected zone are higher than that of the base metal. The highest microhardness of the weld is 290 HV. The microstructure of the weld is mainly granular granular bainite and small amount MA component. Bainitic ferrite is a thin strip of ferrite, fine grain, high grain boundary density. Cu, Ti and other micro-alloying elements formed carbide precipitation strengthening phase distributed in the bainitic ferrite. Grain refinement of the fine-grained granular bainite and the precipitation strengthening of its microalloyed carbides (Cu, Ti) xCy make the weld strength higher than the base metal.