采用光纤激光器对1.5 mm厚TRIP590钢板进行对接焊,观察了接头的宏观形貌和显微组织,测试了其硬度和拉伸性能,分析了焊接速度(0.050,0.067,0.083 m·s-1)对焊缝成形、接头组织与力学性能的影响.结果表明:较低和较高的焊接速度均不利于焊缝成形,焊缝表面均有较大的凹陷,焊接速度对组织与性能影响不大;焊缝区和近焊缝热影响区组织主要为马氏体组织,该区硬度较高,约为母材的2倍;近母材侧热影响区组织主要为铁素体和马氏体组织,且距焊缝越远,马氏体组织越少,硬度也急剧下降;焊接接头的屈服强度和抗拉强度均稍高于母材的,塑性略低于母材的;接头均在母材区发生断裂,且为韧性断裂.
1.5 mm thick TRIP590 steel plates were butt welded by fiber lasers.Then the macro-morphology and microstructure of the joint was observed, the hardness and tensile properties were tested, and the influences of welding speed (0.050, 0.067, 0.083 m·s-1) on the weld seam formation and on the microstructure and mechanical properties of welded joint were analyzed.The results show that a relatively low and high welding speed was not good for the formation of weld seam and led to relatively large depressions on weld seam surface.The welding speed had little influence on the microstructure and properties.The microstructures of weld seam and heat affected zone near weld mainly consisted of martensite, resulting in relatively high hardness of the two zones, which was nearly twice as high as that of base metal.The microstructure of heat affected zone near base metal was mainly composed of martensite and ferrite, and the martensite amounts decreased gradually with the increase of distance to the weld center, leading to the sharp decrease of hardness.Both the yield strength and tensile strength of the joints were slightly higher while the plasticity was slightly lower than those of base metal.The joints fractured in base metal and showed a ductile fracture.
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