摘要:
采用机械合金化(MA)和放电等离子体烧结(SPS)工艺制备了9CrWTi-0.35%Y2O3氧化物弥散强化铁素体-马氏体钢(9CrWTi-0.35%Y2O3/FMs)。利用SPS温度和位移测量装置、 OM、 FE-SEM、 TEM、 EDX表征了材料烧结收缩曲线及热处理前后的显微组织和成分, 并采用电子拉伸试验机测试了室温拉伸性能。结果表明: 9CrWTi/FMs和9CrWTi-0.35%Y2O3/FMs在烧结过程出现液相烧结特征。提高烧结温度和压力, 9CrWTi-0.35%Y2O3/FMs孔隙度减小, 密度提高, 晶粒变细, 抗拉强度增加, 但延伸率仅为2%左右。富集Y—Ti—O的弥散相颗粒大小为5～20 nm, 较均匀地分布在基体上。9CrWTi-0.35%Y2O3/FMs烧结态、 10%盐水淬火态及750 ℃高温回火态的显微组织分别为等轴铁素体、 细长板条马氏体及等轴和残余铁素体。9CrWTi-0.35%Y2O3/FMs烧结体经盐水淬火、 回火后, 抗拉强度、 屈服强度和总延伸率由1554 MPa、 1430 MPa、 1.8%变为1198 MPa、 1006 MPa和12.8%。
Abstract:
9CrWTi-0.35%Y2O3 oxide dispersion strengthened ferritic-martensitic steels were prepared by mechanically alloying (MA) and spark plasma sintering (SPS). SPS temperature and displacement measurement, OM, FE-SEM, TEM and EDX were employed to characterize the shrink curve, the microstructures and chemical composition evolution before and after heat treatment. The tensile properties at room temperature were also investigated by electronic tensile test. The result shows that a liquid phase sintering feature is exhibited in 9CrWTi/FMs and 9CrTWi-0.35%Y2O3/FMs. The density and tensile strength of 9CrWTi-0.35%Y2O3/FMs increase with temperature and pressure, while porosity and grain size decrease and total elongation is only about 2%. Dispersoids about 5-20 nm enriched in Y—Ti—O are uniformly distributed in the matrix. The microstructures are of equiaxed ferritic, slender lath martensite, and mainly equiaxed and residual ferritic SPS, after 10%NaCl water solution quenching and tempering at 750 ℃, respectively. The 9CrWTi-0.35%Y2O3/FMs by SPS exhibits ultimate tensile strength and yield strengthen of 1554 MPa and 1430 MPa, and a total elongation to fracture of 1.8%, while after salt water quenching and tempering, which successively change to 1198 MPa, 1006 MPa and 12.8%, respectively.
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