(哈尔滨工业大学材料科学与工程学院，哈尔滨150001)
摘 要: 上机匣为直升机传动系统中的关键零件，几何形状复杂，性能指标要求高， 成形难度大。 采用纯铅为模拟材料，对上机匣成形方案进行了试验研究，确定了上机匣等温精锻成形分制坯、 终锻、精整三个工步。通过对MB15镁合金塑性图的分析，确定其变形温度范围为350～380℃。 制坯、 终锻时的变形温度取380 ℃，以便金属充填模膛； 精整时的变形温度取350℃，以提高 锻件力学性能。为保证锻件几何精度， 采用锻后直接人工时效的热处理方案(164℃时效24 h). 利用等温精锻工艺成功地锻制出上机匣锻件，锻件的力学性能、显微组织和尺寸精度均符合要求.
关键字: MB15镁合金 等温精锻 上机匣
（School of Materials Science & Engineering,Harbin Institu te of Technology, Harbin 150001, P. R. China）
Abstract:Upper casing, as a key part in the driving system of helicopter, is difficult to be formed owing to its complex geometry and high demand for property. In order to design the forming process properly, the forming process of upper casing was investigated by the aid of physical modelling using pure lead. As a result, is othermal precision forging was adopted to form the upper casing and the forming process consists of three steps, pre-forming, final forging and ironing. Through the analysis of plasticity diagram of MB15 magnesium alloy, the forming temperature range was decided to be 350～380 ℃. The temperature for pre-forming and final forging was 380 ℃, which was helpfulf or the metal to fulfill the die cavity. The ironing temperature was 350℃, which raised the mechanical property of forging. For keeping the geometry precision of the forging, artificial aging was conducted directly after forming and the temperature and time were 164℃ and 24 h respectively. The upper casing was forged successfully with isothermal forging technique. Both the mechanical properties, microstructure and accuracy of forging can satisfy the requirements of the user.
Key words: MB15 magnesium alloy isothermal forging upperc asing
