热处理对一种新型高强亚稳β钛合金冷轧无缝管组织与性能的影响

Effect of Heat Treatment on Microstructures and Mechanical Properties of A New High Strength Metastable β-Titanium Alloy Cold Rolled Seamless Tube

研究了一种新型高强亚稳β型Ti-B17钛合金冷轧无缝管在不同热处理后的显微组织与力学性能的变化规律。结果表明:合金管材的次生α相的尺寸与体积分数是影响力学性能的主要因素。经790℃/1 h+530℃/8 h固溶时效处理后,合金的抗拉强度为1226 MPa,屈服强度为1150 MPa,伸长率为8%;经740℃/1 h+560℃/4 h固溶时效后,合金的抗拉强度为1213 MPa,屈服强度为1109 MPa,伸长率为8.5%,具有良好强-塑性匹配。经790℃/1 h+530℃/8 h和740℃/1 h+560℃/4 h固溶时效后的室温拉伸断口主要由中心的纤维区和韧窝周围的剪切唇区组成,纤维区与剪切唇区存在明显的分界。中心区存在大量的等轴韧窝,呈韧性断裂特征,断裂方式为微孔聚合断裂。

The changes of microstructure and mechanical properties of a new type of high strength metastable β-Ti-B 17 titanium alloy cold rolled seamless tube after different heat treatment were studied. The results show that, the size and the volume fraction of the secondary α phase of the alloy tube are the main factors affecting the mechanical properties. After solid solution and aging treatment of 790 ℃/1 h＋530 ℃/8 h, the ultimate tensile strength of the alloy is 1226 MPa, the yield strength is 1150 MPa and the elongation is 8%; after solid solution and aging treatment of 740℃/1 h＋560℃/4 h, the ultimate tensile strength of the alloy is 1213 MPa, the yield strength is 1109 MPa and the elongation is 8.5%, which has good strength and plasticity matching. The room temperature tensile fracture after solid solution and aging treatment of 790℃/1h＋530℃/8h and 740 ℃/1h＋560 ℃/4 h is mainly composed of the fiber area at the center and the shear lip zone around dimple, and there is a clear boundary between the fiber area and the shear lip zone. There are a large number of equal axis ductile nests in the central area, which show ductile fracture characteristics. Fracture mode is micro-pore polymer fracture.