钛合金常规挤压时冷硬层对成形过程的影响  

Influence of cooling hard layer on titanium alloy conventional extrusion forming process

作　　者：江学强[1] 吉卫[1] 曹海桥[1] 周朝辉[1] 郝爱国[1] 

机构地区：[1]中国工程物理研究院机械制造工艺研究所,四川绵阳621900

出　　处：《锻压技术》2007年第3期127-130,共4页Forging & Stamping Technology

摘　　要：钛合金常规挤压时表面存在很厚的冷硬层,导致挤压抗力急剧升高,严重影响坯料成形。通过TC4杯形件常规挤压研究了该条件下钛合金表面冷硬层性质以及对成形过程的影响,分析了影响冷硬层形成的关键因素及机理。通过采用DEFORM-3D软件模拟分析了常规挤压状态下冷硬层对挤压件形状、应力、应变、载荷等的影响。模拟结果表明,当界面传热系数为11,摩擦系数为0.7时,坯料存在约3 mm、温度约为500℃的冷硬层。实验结果表明,在没有充分润滑和保温的常规挤压条件下凸模易断裂。TC4杯形件在常规挤压条件下成形,必须保证坯料有良好的润滑和保温,可以采用等温挤压、包套挤压或者热模挤压来消除或者减少成形过程的冷硬层。The thick cooling hard layer exists on the surface of titanium alloy billet formed under conventional extrusion condition. The flow stress increases sharply, which affects the billet forming. The properties of cooling hard layer and influence on extrusion forming processes were investigated by simulation and experiment. The key factors affecting cooling hard layer were presented. The thickness and characteristic of cooling hard layer were analyzed by numerical simulation with DEFORM-3D software. The result of numerical simulation shows that cooling hard layer affects forging shape, flow stress, strain, load and so on. The thickness of cooling hard layer was about 3 mm and 500℃ when the interface transferring coefficient was set at 11 and the Diction coefficient was set at 0.7. The result of experiments shows that the punch is easily broken if there is lack of effective lubrication and heat insulation. The effective lubrica tion and heat insulation are necessary conditions for ensuring the TC4 cup-shape part forming. The ideas of isothermal extrusion and wrap extrusion were proposed, which could eliminate or reduce the cooling hard layer.

关 键 词：钛合金 冷硬层 常规挤压 数值模拟 

分 类 号：TG371[金属学及工艺—金属压力加工]