K17镍基铸造高温合金环境损伤的研究

本文研究了镍基铸造高温合金K17在真空、空气和热腐蚀环境中热暴露前后持久性能和高温拉伸性能的变化.结果表明,真空中热暴露对K17合金的持久寿命没有影响,但降低高温瞬时拉伸强度,提高持久塑性和高温瞬时拉伸塑性;空气和热腐蚀环境中热暴露明显降低持久性能和高温瞬时拉伸性能,其中尤以热腐蚀环境最严重,空气环境暴露造成晶界氧化并贫Cr,热腐蚀环境暴露引起晶界严重硫化,晶界两侧贫Cr富S,因而弱化晶界,降低性能.

ENVIRONMENTAL DAMAGE OF CAST Ni-BASE SUPERALLOY K17

Rupture and tensile properties of K17 before and after thermal expo- sure in vacuum, air and hot corrosion environments have been investigated. The results show that vacuum exposure essentially does not affect the rupture lives, but it results in the decrease of high temperature tensile strength and increases of rup- ture and high temperature tensile ductilities; air or hot corrosion environmental ex- posure make the alloy degradation: severely reduce the rupture and high temperature tensile properties, hot corrosion environmental exposure being more harmful. The former causes grain boundary oxidation and depletion of Cr, and the later makes the sulphurization at grain boundaries. That results in the concentration of S and depletion of Cr at grain boundaries and, consequently, weakens the grain bounda- ries.