Affiliation:
1. Shi‐changxu Innovation Center for Advanced Materials Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 P. R. China
2. Department of Materials Physics and Chemistry, School of Materials Science and Engineering, and Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education) Northeastern University Shenyang 110819 P. R. China
Abstract
Cracking resistance is vital to the practical application of spring steels, which consists of fracture toughness (KIC) under the quasistatic loading condition and fatigue crack propagation (FCP) resistance under the cyclic loading condition. In the present study, the relation between the KIC/FCP resistance and microstructure of the 50CrMnSiVNb spring steel tempered at various temperatures is studied. In the results, it is shown that the dislocation density is the main factor influencing the KIC and FCP resistances, and the carbide size/quantity and morphology can also affect the KIC and FCP resistances. Thus, reducing the dislocation density is the most effective method to enhance the cracking resistance of the investigated steel. Moreover, decreasing the aspect ratio and obtaining a moderate size of tempered carbides are also beneficial to the cracking resistance. In addition, free hydrogen atoms can cause intergranular fracture on the fracture surface, worsening the FCP rate. To enhance the FCP resistance, smelting processes need to be improved to reduce the hydrogen content of the investigated steel.
Subject
Materials Chemistry,Metals and Alloys,Physical and Theoretical Chemistry,Condensed Matter Physics