FGH4113A粉末高温合金的裂纹扩展性能研究

Crack Propagation Performance of FGH4113A Powder Metallurgy Superalloy

摘要:

对自主研发的第三代粉末高温合金FGH4113A的裂纹扩展性能进行了研究，包括制备工艺、温度、加载频率对裂纹扩展性能的影响，并与国内外同类高温合金进行了比较。采用热等静压、热挤压、等温锻造（isothermal forging，ITF）与热处理的组合工艺制备合金，实验测试温度包含室温、650 ℃、700 ℃，加载频率为0.33和20 Hz，分析了工艺、温度、加载频率对合金高温裂纹扩展性能的影响，对比了同类合金牌号FGH95、FGH96、FGH97、FGH98、ME3、LSHR的裂纹扩展性能。结果表明：原始粉末颗粒边界（prior particle boundary，PPB）和晶界周围粗大的一次γ′相是合金裂纹扩展性能的不利因素，增大合金晶粒尺寸有利于降低裂纹扩展速率。挤压与锻造工艺能够有效消除PPB，从而提高合金的抗裂纹扩展能力。室温裂纹扩展速率远低于650和700 ℃的裂纹扩展速率，合金0.33 Hz测试频率的裂纹扩展速率明显高于20 Hz，升高温度与降低测试频率均会增大合金的裂纹扩展速率。ITF态FGH4113A合金在稳定裂纹扩展阶段超出FGH98、LSHR和ME3合金，达到了国际上第三代粉末高温合金的先进水平。

Abstract:

The crack propagation performance of the independently-developed 3rd-generation powder metallurgy superalloy FGH4113A was studied, including the effects of preparation process, temperature, and frequency on crack propagation performance, and a comparison was made with similar superalloys. The preparation process involved a combination of hot isostatic pressing, hot extrusion, isothermal forging (ITF), and heat treatment. Test temperatures included room temperature, 650 ℃, and 700 ℃, with test frequencies of 0.33 and 20 Hz. The effects of process, temperature, and frequency on the high-temperature crack propagation performance of the alloy were analyzed. The crack propagation performance of similar alloys with grades such as FGH95, FGH96, FGH97, FGH98, ME3, and LSHR was compared. The results show that prior particle boundary (PPB) and coarse primary γ′ phase around the grain boundary are unfavorable factors for the crack growth performance of the alloy, and increasing the grain size is beneficial to reducing the crack propagation rate. Extrusion and forging process can effectively eliminate PPB, thereby enhancing the crack propagation resistance of the alloy. The crack propagation rate at room temperature is much lower than that at 650 and 700 ℃, and the crack propagation rate at test frequency of 0.33 Hz is significantly higher than that at 20 Hz. Increasing the temperature and decreasing the test frequency will increase the crack propagation rate of the alloy. In the stable crack propagation stage, the FGH4113A alloy in ITF state exceeds FGH98, LSHR, and ME3 alloys, and reaches the advanced level of the 3rd-generation powder metallurgy superalloy.