某特殊需求的大规格TC4钛合金棒材制备工艺研究

为给某特殊锻件提供满足缺口应力断裂性能的大规格TC4钛合金棒材,将3次真空自耗熔炼得到的5 t重的Ф720 mm TC4钛合金铸锭,分别采用β相区开坯+两相区直拔锻造和β相区开坯+两相区锻造(镦拔+直拔)两种工艺,制成Ф350 mm TC4钛合金棒材。第二种工艺制备的锻棒组织的均匀性及等轴化程度、超声波探伤水平均优于第一种工艺制备的棒材;普通退火处理后棒材的室温塑性和缺口应力断裂性能也较好;各项技术指标均符合标准要求。

Research on Preparation of Large-sized TC4 Titanium Alloy Bar for Special Needs

To meet the notch stress fracture property needs of some special forgings,the720 mm TC4 titanium alloy ingot weighed 5 t was produced by triple VAR（ vacuum arc remelting）process,and350 mm bars were forged by theβforging ＋（α＋β）drawing,and theβforging ＋（α＋β）upsetting and drawing,respectively. The bar forged by the second process has more uniformity and equiaxed microstructure and better noise level in ultrasonic testing than which forged by the first process. After the annealing,the bars forged by latter process has better plasticity and the notch stress fracture property,which can accord with the requirement of the standard.