Annealing treatment for improving the mechanical properties of 00Cr18Nb ferritic stainless steel prepared by investment casting

Abstract The as-cast and annealed mechanical properties of 00Cr18Nb ferritic stainless steel prepared by investment casting process were studied. Experimental results indicated that the problem of unstable plastic fluctuations in the as-cast state can be effectively solved by annealing treatment. The plasticity of the investment-cast 00Cr18Nb steel after annealing at 800 and 850 °C was more stable than that of 900 °C. It showed that the optimum annealing condition was 850 °C for 2 h with the appropriate elongation and tensile strength of 26.3 ± 0.4% and 513 ± 4 MPa, respectively. The main reason for annealing to improve plasticity is the Laves phase in the microstructure, which has better effects on mechanical properties than (Ti,Nb)(C,N) particles and grain size. With the increase of annealing temperature and time, the size of Laves phase tended to increase. The size, quantity, morphology and distribution of Laves phase after annealing are closely related to the mechanical properties. The Laves phase with a large amount of uniform distribution in the form of small particles can effectively improve the mechanical properties after annealing treatment.