热处理工艺对Inconel718C改型合金组织和性能的影响

Effects of Heat Treatment on Microstructure and Mechanical Properties of Modified Inconel 718C Alloy

通过力学性能检测、X射线衍射、光学和扫描电镜观察,研究了热处理工艺对改型Inconel718C镍基高温合金微观组织、拉伸性能、持久性能以及蠕变行为的影响。结果表明,较高温度均匀化热处理可显著改善合金中元素的偏析,可消除合金中的Laves相。均匀化温度较低时残存少量Laves相,对合金强度无影响,但严重降低合金的塑性和700℃/620 MPa时的持久寿命。在中间热处理过程中,晶界δ相的析出显著降低合金的室温和700℃拉伸强度和塑性;δ相的析出增大了合金的稳态蠕变速率,加速了蠕变第三阶段的发生,这主要是由于在蠕变过程中δ相附近微孔聚集长大所致。

The effects of heat treatment process on microstructures, tensile properties, stress-rupture properties and creep behavior were investigated in a modified Ni-based cast superalloy by means of mechanical tensile test, OM and SEM observations. The results show that higher homogenizing temperature can reduce the segregation and remove the Laves phase of the alloy. Some amount of Laves phase, remaining after lower temperature homogenizing treatment, has no detrimental effect on the strength,while it remarkably reduces the plasticity and the rupture life at 700 ℃/620 MPa. The δ phase, precipitating on the grain boundaries of the alloy during the intermediate heat treatment, reduces the tensile strength and plasticity at both room temperature and 700 ℃. With the precipitation of δ phase on the grain boundaries, the steady creep rate is increased and the start of the third stage creep curve is advanced, due to void growth and eoaleseenee in the region beside the δ phase.