热等静压及恢复热处理工艺对DZ125蠕变损伤的影响

选用4种不同参数的热等静压及恢复热处理工艺对DZ125蠕变损伤试样进行显微组织演化的研究,并进行力学性能评价。结果表明:DZ125合金经预持久损伤实验后,显微组织出现了γ′相退化、蠕变孔洞形成等,但是碳化物没有出现由MC型向M_(23)C_6及M6C型分解。此外,热等静压的温度在孔洞愈合过程中作用显著,1200℃及1250℃温度下分别出现了γ′同心筏排结构及合金的初熔现象。同时,通过选取合适的热等静压参数,可以避免内部再结晶的产生。合理的热等静压及恢复热处理工艺可以改善蠕变损伤的显微组织,并使其显微硬度达到原始态水平,且持久寿命得到提高。

Effect of HIP Combined with RHT Process on Creep Damage of DZ125 Superalloy

Four different processes of hot isostatic pressing (HIP) combined with rejuvenation heat treatments (RHT) were adopted to reveal the microstructural evolution of creep damaged DZ125 spec-imens ,finally the mechanical properties were evaluated .The results show that both γ′precipitate de-generation and creep cavities for the creep damaged DZ125 superalloy are found after the pre-endur-ance damage test .However ,the carbided compositions from MC type to M23C6 type or M6C type has not been observed for DZ125 .In addition ,it is found that the HIP temperature play a dominant role in the cavity healing process for the damaged specimens .The concentrically oriented γ′rafting structure and the incipient melting are observed at 1200℃ and 1250℃ respectively .Meanwhile ,it is found that the appropriate HIP schedule adopted can effectively avoid the internal recrystallization for the direc-tionally solidified nickel-based superalloy DZ125 .The appropriate HIP schedule combined with RHT process can successfully restore the microstructure induced by creep damage and recover the degraded micro-hardness to the original one ,in addition improve the creep rupture life .