Influence of Spheroidizing Treatment on the Graphite and Mechanical Properties of Cast High-nickel Austenitic Ductile Iron

Abstract

Cast high-nickel austenitic ductile iron (CHNADI) is widely used in high temperature, low temperature and strong corrosive environments due to its good comprehensive mechanical properties. However, its low yield strength limits its application in nuclear power equipment. Herein, the influence of nodularizer and processing temperature on the graphite and mechanical properties of CHNADI was investigated to significantly promote its properties. With the increase of nodularizer dosage, the mechanical properties of tensile strength, yield strength, elongation, and impact toughness first increase and then decrease. When the dosage of nodularizer is 0.9 mass% and the processing temperature is 1 480°C, CHNADI exhibits excellent mechanical properties with the hardness of 132 HB, tensile strength of 450 MPa, yield strength of 224 MPa, elongation rate of 46% and impact toughness of 91 J. In this work, a new strategy of preparing CHNADI without heat treatment is proposed to meet the strict requirements of this material, which is significant for the development of CHNADI.

Mechanism Analysis for the Enhancement of Low-Temperature Impact Toughness of Nodular Cast Iron by Heat Treatment

“…It was reported that through appropriate heat treatment processes, the impact toughness of ductile iron under low-temperature conditions can be markedly enhanced, thereby avoiding the brittle fracture. This innovative approach can make much wider applications for ductile iron [16][17][18].…”