800 MPa级高强钢焊接接头组织及力学性能

采用焊条电弧焊和气体保护焊两种方法，分别对具有良好抗焊接裂纹敏感性的800 MPa级船体用钢对接接头进行两种工艺的焊接，并对其焊接接头进行显微组织分析和力学性能试验. 结果表明，两种焊接方法焊缝组织主要为交织分布的板条马氏体、贝氏体，以及一定量的针状铁素体，板条间有残余奥氏体，SMAW(焊条电弧焊)焊缝宏观金相可见明显氧化夹杂；两种焊接方法所得焊接接头具有相似的硬度分布，抗拉强度相当，且均断在母材，但SMAW侧弯试验件出现0.5 mm裂纹；?50 ℃下SMAW接头冲击韧性低于GMAW(气体保护焊)接头，SMAW断口由河流花样的准解离小刻面和少量的韧窝组成的撕裂棱构成，属于韧-脆混合断裂，GMAW断口由小且深的韧窝构成，属于典型的韧性断裂.

Study on the welding joint microstructure and mechanical properties of 800 MPa grade high stress steel

The welding of 800 MPa grade high stress steel with good resistance to welding crack was carried out by SMAW and GMAW. The microstructure analysis and mechanical properties of the welded joint were finished. The results show that under the two welding methods, the weld structure is mainly covered with interwoven lath martensite and lath bainite, as well as a certain amount of acicular ferrite, between the lath is some residual austenite, and the oxidative inclusions were obviously found in SMAW weld Macroscopic metallographic; The welding joints obtained by the two welding methods have similar hardness distribution, the tensile strength is equivalent, and both are broken in the base material, but the side bending test pieces of SMAW appeared 0.5 mm cracking; The impact toughness of the SMAW joint is lower than that of the GMAW joint at ?50 ℃. The SMAW fracture is composed of the quasi-dissociation of the facies and a small number of dimples, which belongs to the ductile-brittle fracture. And the GMAW fracture is composed of small and deep dimples, belonging to the typical ductile fracture.