The Effect of Vanadium Content on Microstructure and Impact Toughness of Forged High Alloy Steel X96CrMo12-1

摘要

The aim of this research was to examine the influence of vanadium on the structure and impact toughness of the forged high alloy steel X96CrMo12-1. It is known that vanadium affects the process of solidification of this alloy by narrowing the temperature interval of crystallization. Vanadium, as an alloying element, moves liquids and solidus lines toward higher temperatures, approximately for 25-30 degrees C. In addition, vanadium forms V6C5 carbides, which are partly distributed between the present phases in the steel, carbide (Cr,Fe)(7)C-3 and austenite. The presence of vanadium enables the formation of (Cr,Fe)(23)C-6 carbide and its precipitation into austenite during the cooling process. In local areas around fine carbide particles, austenite is transformed into martensite, i.e., vanadium reduces remained austenite and improves quenching process. Studies have shown that as the content of vanadium increases up to 5%, the impact toughness of this steel is significantly increased. The steel X96CrMo12-1 contains remarkably less carbon than high alloyed Cr-Mo ledeburite steels and does not contain a eutectic microconstituent in the structure. So it can be treated by forging process thus provide a more compact and tougher structure. The basic problem in the application of high alloyed Cr-Mo steels is to increase their impact toughness, while sustain a relatively high value of hardness. Studies have shown that vanadium strongly increases toughness while retaining high hardness, which is a requirement for wear-resistant steels.