工艺过程对火花塞用GH600镍基高温合金组织与抗氧化性能的影响

Effects of process on the microstructure and anti-oxidation property of GH600 nickel-base superalloys for spark plug

采用铸造–电渣重熔–锻造–拉拔工艺制备火花塞用GH600镍基高温合金,研究工艺过程对合金的显微组织、抗氧化性能尤其是氧化膜物相及结构的影响。结果表明,铸造合金晶粒较粗大,并存在许多孔洞和杂质;电渣重熔能净化合金、减少缩孔;锻造和拉拔使得合金晶粒逐步细化。铸造合金的表面氧化膜不完整且易剥落,在900℃氧化100 h后的质量增加量为1.74 mg/cm^2,随着电渣重熔、锻造、拉拔工艺的进行,氧化膜变得完整致密,锻造合金和拉拔合金表面均出现结节状氧化物,抗氧化性能逐渐提高,电渣重熔、锻造、拉拔合金氧化后的质量增加量分别降低到1.17,0.71和0.51 mg/cm^2。铸造、电渣重熔和锻造合金表面形成双层结构氧化膜,外层主要为NiO和Ni Fe2O4,内层为Cr的富集层。拉拔合金表面形成双层结构氧化膜后,其内部又形成类似的双层氧化膜,最终形成4层结构的氧化膜。

Nickel-based superalloy used in spark plugs was prepared by casting-electroslag remelting-forging-drawing processes.The effects of the processing on the microstructure and oxidation resistance of the Nickel-based superalloys,especially the phase composition and morphology of the formed oxide layers were studied.The results show that,the grain size of casting alloy is large and pores and impurities were found.Electroslag remelting process can improve the purity of the alloy,while reducing the shrinkage of the material.The forging and drawing process can make the grain of the alloy refinement.The oxide layer on the surface of the casting alloy is incomplete and easy to peel off.Weight gain of the casting alloy after oxidation at 900℃for 100 h is 1.74 mg/cm^2.With the process of electroslag remelting,forging and drawing,the oxide layer becomes complete and compact.Nodular oxides appear on the surface of forging alloy and drawing alloy,and their antioxidant properties are gradually improved.Weight gain of electroslag remelting,forging and drawing alloys after oxidation are reduced to 1.17,0.71 and 0.51 mg/cm^2,respectively.Casting,electroslag remelting and forging alloys form a double-layer oxide layers,the outer oxide layer is mainly composed of NiO and NiFe2O4,while the inner oxide layer is an enriched area of Cr.After the double-layer oxide layer is formed on the surface of the drawing alloy,a similar double-layer oxide layer is formed inside the alloy,and finally a four-layer oxide layer is formed in drawing alloy.