磷含量对细晶镍基GH4133合金力学性能的影响

EFFECT OF PHOSPHORUS ON MECHANICAL PROPERTIES OF FINE-GRAINED GH4133 NICKEL BASE SUPERALLOY

适当磷含量可提高细晶镍基GH4133合金的力学性能。采用控制热加工和热处理的方法将GH4133合金的晶粒度细化至ASTM 10级。该细晶合金的最低屈服强度比晶粒度为ASTM 4—5级正常组织的合金高200 MPa以上,最低断裂强度高150 MPa以上。磷含量为0.140％(质量分数,下同)的细晶合金的屈服强度相对于正常磷含量(0.005％)的细晶合金又高约100 MPa,断裂强度约高50 MPa。镍基GH4133合金中,磷含量低于0.140％,拉伸试样均呈穿晶断裂。磷含量低于0.023％时,冲击断口呈穿晶断裂,冲击韧性高于70 MJ/m^2;磷含量升至0.140％时,冲击断口部分区域呈沿晶断裂,冲击韧性约降至40 MJ/m^2。延长GH4133合金持久寿命的最佳磷含量位于0.011％附近。结合位错与磷原子气团的相互作用讨论了上述不同载荷方式下磷对合金力学性能的影响特点。

Apposite phosphorus content can improve the mechanical properties of the finegrained GH4133 nickel-base superalloy. The grain size of the alloy was refined to ASTM 8-10 grade by controlling the thermal processing and the heat treatment. The tensile specimens fail by intergranular fracture even when the phosphorus level is as high as 0.140% (mass fraction). The yield and ultimate strengths of the refined alloy are 200 and 150 MPa higher than that of the alloy with a standard microstructure of ASTM 4-5 grain size, respectively. And the above two strengths of the alloy with 0.140% phosphorus are 100 and 50 MPa higher than those of the alloy with a industrial controlled phosphorus level, say 0.005%. The impact specimens fail by intragranular fracture when the phosphorus level is below 0.023% and the fracture toughness of the alloy is higher than 70 MJ/m(2). Some parts of the fracture surface of the impact specimen with 0.140% phosphorus exhibited intergranular fracture characteristics and the fracture toughness is lowered to about 40 MJ/m(2). Phosphorus extends the rupture life of the GH4133 alloy and its optimum addition is around 0.011%. The interaction between phosphorus atmosphere and dislocations is discussed to understand the effect of phosphorus on different type of mechanical properties.