【摘要】 对BT20钛合金及其激光焊接接头的断裂韧性进行了研究。同时分析了合金及激光焊接接头的硬度分布及显微组织。断裂实验表明,除了一个焊接接头紧凑拉伸(CT)试样是脆性启裂外,其它CT试样均在裂纹延性启裂并缓慢扩展后,发生脆性失稳断裂。母材的断裂韧性明显高于焊接接头,轧制方向对母材断裂韧性的影响不明显。焊接热影响区的断裂韧性介于母材和焊缝金属之间。本研究采用的焊后热处理没有改善焊接接头的断裂韧性,还有进一步恶化的趋势。添加活性剂对焊缝金属的断裂韧性没有明显作用,但对延性裂纹扩展长度有所改善。更多还原

【Abstract】 Fracture toughness test on Ti alloy BT20 and laser-welded joints was carried out.Meanw- hile, hardness distribution and microstructure of the alloy and welded joints were investigated. Fracture test indicated that brittle unstable fracture occured after ductile crack initiation and slow propagation for all the compact tension (CT) specimens, except one welded joint specimen was brittle crack initiation. Fracture toughness of base metal was obviously higher than that of welded joint, and rolling directions had no obvious effect on fracture toughness of base metal. Fracture toughness of heat-affected zone(HAZ) was between the base metal and weld metal. Postweld heat treatment not only not improved the fracture toughness of welded joint, but also had the trend of deterioration. Addition of activating agent had no obvious effect on fracture toughness of weld metal, but it improved the length of ductile crack propagation.更多还原