φ1500mm 级GH4738合金涡轮盘锻件热加工工艺研究

Research on Hot Working Process of φ1500mm Class GH4738 Alloy Turbine Disk Forged Parts

摘要:

动力装备用超大规格GH4738合金涡轮盘锻件直径达φ1500mm以上，是国内最大的GH4738合金锻件。采用Simufact数值模拟软件分析了摩擦系数、压制速度、始锻温度等参数对锻件的成形载荷、微观组织分布的影响，确定了φ1500mm级GH4738合金涡轮盘的最佳锻造工艺参数。同时，采用相同工艺参数开展了缩比件的数值模拟与试制分析，实际组织分布与模拟结果保持一致。基于验证结果，在8万吨模锻压力机上完成了φ1500mm级GH4738合金涡轮盘模锻成形，锻件经热处理后组织性能满足使用要求，实现φ1500mm级GH4738合金涡轮盘锻件工程化制备。同时采用TEM定量表征了锻件不同位置析出相含量，分析得出超大规格锻件在淬火冷却过程中，截面不同位置的固溶降温不均匀这一尺寸效应引起最终锻件时效后表面二次γ"析出相含量明显高于心部位置，并导致不同位置拉伸性能存在明显差异。

Abstract:

The ultra-large-scale GH4738 superalloy turbine disk forging for power equipment, with a diameter exceeding φ1500 mm, represents the largest GH4738 alloy forging domestically. Using the Simufact numerical simulation software, the effects of process parameters such as friction coefficient, pressing speed, and initial forging temperature on the forming load and microstructure distribution of the forging were analyzed, and the optimal forging process parameters for the φ1500 mm-scale GH4738 alloy turbine disk were determined. Subsequently, numerical simulation and trial production of a scaled-down component were conducted using the same process parameters, and the actual microstructure distribution was found to be consistent with the simulation results. Based on the validated results, die forging of the φ1500 mm-scale GH4738 alloy turbine disk was successfully carried out on an 80,000-ton die forging press. After heat treatment, the microstructure and mechanical properties of the forging met the service requirements, achieving the engineering fabrication of the φ1500 mm-scale GH4738 alloy turbine disk forging. Furthermore, the precipitate phase content at different positions of the forging was quantitatively characterized using TEM. It was revealed that during the quenching process of the ultra-large-scale forging, the non-uniform solid-solution cooling rate at different cross-sectional positions—attributed to the size effect—resulted in a significantly higher content of secondary γ" precipitates on the surface than at the core after subsequent aging, leading to notable differences in tensile properties across different positions.