热处理对激光金属成形DZ125L高温合金组织及硬度的影响

Effects of Heat Treatment on Microstructure and Micro-hardness of Laser Metal Forming DZ125L Superalloy

研究激光金属成形DZ125L高温合金的组织,其形成的非平衡组织致密,一次枝晶间距约5μm;生成的过饱和固溶体抑制γ′相析出,且晶界析出点状不连续MC碳化物。这无法满足高温合金直接使用要求,需进行必要热处理。因此研究了5种热处理状态下的组织和显微硬度,结果表明均匀化和固溶处理十分必要,但需严格控制时间;时效处理时间可以适当减少。经过热处理试样的硬度比未经过过热处理试样硬度低,主要原因是激光金属成形组织细密,晶界析出大量强化相MC碳化物。

The microstrueture of laser metal forming DZ125L superalloy was studied first. The non- equilibrium microstructure is dense, the primary spacing of dendrites is about 5ttna; the generated su- persaturated solid solution inhibits ）/ phase precipitation and punctuated MC carbides precipitates at the grain boundaries. Unless the necessary heat treatment, it Couldn＇t be used directly. Studies of mi- erostructure and micro-hardness on five kinds condition of heat treatment were carried out. The re- sults show that the homogenization and solution treatment is necessary, but the time must be strictly control; the aging time can be reduced properly. The micro-hardness of the sample which fabricated with heat treatment is the lower than that with as deposit,as the microstructure is dense and strength- ening phase MC carbide precipitates at grain boundary