置氢TC4钛合金等温锻造叶片组织演变规律

为了降低钛合金叶片的锻造温度和改善其组织性能,基于氢致钛合金高温增塑机理,将热氢处理技术应用于钛合金叶片的等温锻造成形工艺中.观察和对比分析了未置氢TC4钛合金和置氢TC4钛合金叶片等温锻造后的组织以及真空除氢热处理和普通热处理工艺下的组织演变.实验结果表明:置氢降低了TC4钛合金叶片的等温锻造载荷,除氢热处理后组织得到改善,获得了含有细小、等轴α晶粒的双态组织.确定了置氢量为0.25%(质量分数)的TC4钛合金适宜的热处理工艺为:锻后在750℃真空脱氢保温5h,900℃退火1h后再450℃时效4h.

Microstructural evolution of isothermal forged hydrogenated TC4 titanium alloy blade

In order to decrease the forging temperature and improve the microstructure and properties of titanium alloy blade,based on the theory of hydrogen-induced plasticity enhancement at elevated temperature,thermohydrogen treatment technology was used in the forging process of titanium alloy blade in this paper.Microstructures of hydrogenated TC4 titanium alloy blade and TC4 titanium alloy blade without hydrogen forged at different conditions were investigated.The microstructures of hydrogenated TC4 alloy and TC4 alloy without hydrogen after dehydrogenation treatment in vacuum and common heat treatment processes were compared.Results show that hydrogenation can decrease the forging load of TC4 titanium alloy blade.The microstructure is improved after heat treatment and the bimodal microstructure with fine equiaxed α phase is obtained.The reasonable heat treatment parameters of TC4 titanium alloy blade with 0.25wt.% hydrogen are dehydrogenation treatment in vacuum at 750℃ for 5 h after forging,then 900℃ anneal treatment for 1 h and 450 ℃ ag-ing treatment for 4 h in conventional furnace.