C和B的含量对K417G镍基高温合金的凝固行为和高温持久性能的影响

对不同C、B含量的K417G合金进行DTA分析、等温淬火实验和950℃/235 MPa持久性能测试,并观察其组织形貌,研究了C、B含量对K417G镍基高温合金的凝固行为和高温持久性能的影响.结果 表明,在合金的凝固期间C含量影响碳化物的析出温度和初生碳化物的含量,且随着C含量的提高而提高;共晶组织的析出温度主要受B元素...

Influence of C-and B-content on Solidification and High Temperature Stress Rupture Behavior of Nickel-based Superalloy K417G

The influence of C- and B-content on the solidification and high temperature stress rupture behavior of K417G nickel-based superalloy have been investigated by means of DTA analysis, optical microscope, scanning electron microscope, isothermal quenching and stress rupture tests at 950℃/235 MPa. Results show that the precipitation temperature and the amounts of the primary carbide are mainly affected by the C-content, which are both increased with the rise of C-content in the alloy. During stress rupture deformation at 950℃/235 MPa, the fracture mechanism of the alloy can be described as that cracks initiate on and then propagate along grain boundaries. Wherein, the MC-type carbides on the grain boundary could decompose into M₂₃C₆-type carbide enriched in Cr, which will reduce the stability of the boundary. Within the composition range of the tested alloys, raising the B-content could increase the grain boundary strength of the alloy during deformation at high temperature. As a result, the proper decrease C-content, while increase B-content can improve the high temperature stress rupture property of the alloy.