Effect of Phosphorus on Mechanical Properties of Fine-Grained GH4133 Nickel Base Superalloy
磷含量对细晶镍基GH4133合金力学性能的影响

Apposite phosphorus content can improve the mechanical properties of the fine-grained 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/m2. 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/m2. 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.