30CrMnSiNi2A钢在航空工业主要用于机翼大梁、起落架、连接螺栓等受力构件。本文采用5kWCO2激光焊接超高强度30CrMnSiNi2A钢，以获得性能优良的焊接接头，重点研究了该钢激光焊接接头的组织特征和力学性能。结果表明，焊缝中心区组织为等轴晶、近中心区组织为枝状晶、边缘区组织为粗大的柱状晶、熔合区组织为细长柱状晶和细小等轴晶，热影响区（H.A.Z）组织主要为板条马氏体、贝氏体和少量残余奥氏体；焊缝区主要由α-Fe、Ni-Cr-Fe、Fe-Cr、FeSi2以及MnSi等相组成；焊缝区的硬度最高值约为Hv524，H.A.Z硬度最高值约为Hv560，从H.A.Z到基材硬度明显下降；激光焊接焊缝中心区的残余应力较传统焊接要低，同时激光焊接产生亚稳残余奥氏体有效地改变焊缝和热影响区的综合性能；焊接接头的抗拉强度值约为800MPa，断口出现在靠近焊缝的母材区，焊后热处理的抗拉强度值约为1500MPa，断口均出现在近焊缝区，其断裂均为韧性断裂；焊接接头的冲击韧性平均冲击吸收功为57.65J/mm2；焊接接头的抗腐蚀性能明显比基材好。
关键词：30CrMnSiNi2A钢,激光焊接,组织,力学性能
Microstructure and mechanical properties of 30CrMnSiNi2A steel by laser welding
Abstract
30CrMnSiNi2A steel is mainly applied in wing beams, landing gear, connecting bolts and so on in the aviation industry. To obtain excellent welding joint, 30CrMnSiNi2A is welded by 5kWCO2 laser. Microstructure and mechanical properties are emphatically investigated . The experimental results indicate that microstructure of central welding zone, near central zone and edge zone is equiaxed crystal, dendrite crystal and rough cylindrical crystal, respectively. Microstructure of fusion zone is fine cylindrical and equiaxed crystal. Microstructure of heat-affected zone (H.A.Z) is mainly lath martensite, bainite and residual austenite. The phases of welding zone is mainly comprised of α-Fe, Ni-Cr-Fe,Fe-Cr,FeSi2 and MnSi .The highest hardness value of welding zone is Hv524 , the highest value hardness of H.A.Z is Hv560. The hardness decreases significantly from H.A.Z to substrate. The residual stress is lower than traditional welding, moreover, the comprehensive performance of weld zone and H.A.Z is effectively improved by metastable retained austenite. The tensile strength of welding joints is approximately 800MPa, the fracture appears in substrate near welding zone. However, the tensile strength of joints done by heat treatment is about 1500MPa, the fracture appears in near welding zone. The fracture of joints is all toughness fracture. The average impact absorbed energy of welded joints is about 57.65 J/mm2. The anti-corrosion of welded joints is significantly better than that of substrate.
Key words：30CrMnSiNi2A steel, laser welding，microstructure, mechanical properties
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