变截面TA15钛合金大锻件初生α相控制与定量估算方法

Quantitative Calculation and Control of Primary α Phase for the Variable Sections in Large TA15 Titanium Alloy Forging

摘要:

研究了TA15钛合金变截面大型锻件初生α相含量与室温和500℃高温拉伸性能的关系,系统分析了TA15钛合金两相区锻造工艺窗口内锻造加热温度、冷却速率、截面厚度、加热火次等参数对初生α相含量的影响规律。结果表明:加热温度高、冷却速率快、截面厚度薄、加热火次多,初生α相含量低;反之亦然,并给出了定量关系。对于大型复杂TA15钛合金锻件的制备,在制订工艺时必须充分考虑各种因素的影响,在了解初生α相含量对性能影响规律的基础上,根据服役性能要求,控制初生α相的含量。

Abstract:

For a large and complex shaped TA15 titanium alloy forging,the content of primary α phase generally changes with the size of the different sections and would significantly affects the mechanical properties whenever at the room temperature and high temperature. The relationship of the content of primary α phase and tensile strength at the room temperature and 500 ℃ was measured and realized in the paper. In order to control the α phase content,the influences of the forging process parameters on the content of α phase were systematically studied. The parameters included heating temperature,cooling way,section thickness and heating times within the selectable process window.The result shows that α phase content decreases with the increase of heating temperature and cooling rate,heating times,and also decreases with the thinning of the sample thickness and vice versa. Finally,the equations were obtained for calculating the content of the α phase resulted from the forging process parameters. Various factors on αphase content should be considered when we make a process route to fabricate a large forging. Therefore,to meet the requirement of the in-serve performance,primary α content control could be feasible relying on the relationship between the proportion of α phase and the mechanical properties.