钛合金因其优异的性能而被广泛应用于能源化工、海洋装备、航空航天、汽车制造等领域，其中TC4钛合金因具有抗腐蚀性强、质量轻以及强韧性好等特点被广泛用于这些领域的核心构件中。非等温锻造是钛合金常用的一种加工方法，然而锻造后的钛合金往往会形成粗大不均匀组织，对构件的服役性能有着极大的影响，因此还需要进行强化热处理。对于钛合金而言，固溶时效处理是提高其力学性能并强化其使用性能的重要手段之一。钛合金锻件经过固溶时效后虽能提高强度，但同时带来了较大的残余应力，使得锻件的疲劳寿命、尺寸稳定性和材料强度都会受到严重影响。因此，量化和预测钛合金锻件在固溶时效过程中引入的残余应力，并对其进行合理调控，能进一步满足锻件高可靠性、长寿命的需求。

本文以TC4钛合金非等温锻件为研究对象，采用实验研究、数值模拟与理论分析相结合的方法，揭示锻件固溶时效工艺参数与残余应力的映射关系，主要研究内容如下：

1. 根据工程实际并结合TC4钛合金材料性质选取了关键固溶时效工艺参数并制定了合理的固溶时效实验、残余应力以及力学性能检测实验；在非等温锻造数值模拟的基础上建立了TC4钛合金锻件固溶时效有限元模型，并结合实验结果对模型进行了修正，为后续工艺参数对残余应力的影响分析奠定基础；

2. 基于修正后的有限元模型，分析了TC4钛合金锻件内部残余应力的分布情况，对锻件固溶时效过程中影响残余应力的关键因素（温度场、应力场）进行了研究；分别揭示了固溶温度、固溶时间、时效温度、时效时间对锻件在纵向和横向方向上残余应力分布的影响规律；

3. 以修正后的仿真数据为样本，利用正交实验方法分析了固溶时效工艺参数对锻件残余应力影响的主次关系，并确定了残余应力最优的工艺参数组；结合回归分析法与BP神经网络分别建立了锻件固溶时效残余应力的预测模型，最后对比分析两种模型，将精度较高的作为锻件残余应力的预测模型。

本文的研究结果明确了TC4钛合金非等温锻件固溶时效工艺参数对其残余应力的影响规律，对于改善锻件固溶时效后的残余应力以及工艺参数的优化具有重要的工程指导意义。

Titanium alloy is extensively applied in the fields of energy-chemical industry, marine engineering, aerospace, motor industry and so on because of its excellent performance. TC4 titanium alloy is diffusely used in core components in these fields due to its corrosion resistance, light weight and obdurability. Non isothermal forging is a common processing method of titanium alloy. However, the forged titanium alloy often forms rough and non-uniform microstructure, which has a great influence on the service performance of components. Hence, heat treatment is needed for strengthening. For titanium alloy, solution aging treatment is one of the important means to improve its mechanical properties and strengthen its service properties. Although solution aging improves the strength of titanium alloy forgings, it also brings large residual stress, which will extremely affect the fatigue life, dimensional stability and material strength of forgings. Therefore, quantifying and predicting the residual stress introduced in the solid solution aging process and adjusting it reasonably can further meet the needs of high reliability and long life of titanium alloy forgings.

Taking TC4 titanium alloy non-isothermal forgings as the research object, the mapping relationship between process parameters and residual stress of forgings during solution aging was revealed by combining experimental research, numerical simulation and theoretical analysis. The main research contents are as follows

1. According to the engineering practice and combined with the properties of TC4 titanium alloy, the key solution aging process parameters were selected, and the reasonable solution aging experiment, residual stress and mechanical performance test were formulated. Based on the numerical simulation of non-isothermal forging, the finite element model of solution aging of TC4 titanium alloy forgings was established and modified with the experimental results, which lays a foundation for the subsequent analysis of the influence of process parameters on residual stress.

2. Based on the revised finite element model, the internal residual stress distribution of TC4 titanium alloy forgings was analyzed. The changes of temperature field and stress field, which are the key factors for forming residual stress during solution aging of forgings, were studied. The effects of solution temperature, solution time, aging temperature and aging time on the distribution of residual stress in longitudinal and transverse directions of forgings were investigated respectively.

3. Using the modified simulation data as sample, the primary and secondary relationship of the influence of solution aging process parameters on the residual stress of forging was analyzed by orthogonal experiment method, and the optimal process parameter group of residual stress was determined. Combined with regression analysis and BP neural network, the prediction models of residual stress of forgings after solution aging were established respectively. Finally, the two models were compared and analyzed, and the one with higher accuracy was used as the prediction model of residual stress of the forging.

The results of this paper clarify the influence law of solution aging process parameters on residual stress of TC4 titanium alloy non-isothermal forgings, which has important engineering guiding significance for reducing the residual stress of TC4 titanium alloy forgings after solution aging and optimizing process parameters.

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