退火对BWELDY960QL焊接接头组织与性能的影响

为了研究退火处理对焊接接头显微组织与力学性能的影响,采用CO₂气体保护焊对高强调质钢BWELDY960QL进行了焊接.结果表明,BWELDY960QL钢焊接接头的焊缝区由针状铁素体加先共析铁素体及少量珠光体组成,晶粒细小且分布均匀; 退火处理使针状铁素体数量明显增加,但退火温度过高,会使铁素体组织长大,出现一定数量的魏氏铁素体; 母材与焊丝之间Cr含量存在较大的差异,退火使Cr由热影响区向焊缝迁移; 经过退火处理后,焊接接头的力学性能得到明显改善,其中经过550 ℃退火后,焊件的综合力学性能最好.

Influence of annealing treatment on microstructures and properties of BWELDY960QL welded joint

In order to research the influence of annealing treatment on both microstructures and mechanical properties of welded joint, the high-strength and tempered BWELDY960QL steel was welded with CO₂ gas shielded arc welding. The results show that the microstructure in the welding seam zone of BWELDY960QL steel welded joint is composed of acicular ferrite plus pro-eutectoid ferrite and a small amount of pearlite. In addition, the grains are fine and distribute homogeneously. The amount of acicular ferrite significantly increases after annealing treatment. However, when the annealing temperature is too high, the ferrite will grow up, and certain amount of widmanstaten ferrite will appear. The content of Cr element between the base metal and welding wire is quite different, and the annealing treatment makes the Cr element migrate from the heat affected zone(HAZ)to the welding seam. After the annealing treatment, the mechanical properties of welded joint get significantly improved, and the best comprehensive mechanical properties of weldment are obtained after annealing at 550 ℃.