钒：改造未来

The Influence of Nitrogen on the Microstructure and Mechanical Properties of Microalloyed Steels

Abstract:

Ferritic steels with high nitrogen contents (70 to 110 ppm) are often not utilized because of apparently harmful effects of nitrogen to both the base metal and weld area. Vanadium additions to high nitrogen steels offer distinct advantages in utilizing two mechanisms to obtain increased strengthening: grain refinement and precipitation hardening. The precipitation of V(C,N) is also effective in removing N from solid solution in ferrite and making the steel non-aging. In addition, with proper control over heat input and weld metal composition, it is possible to maintain good mechanical properties in the weld as well. This report details the effect of nitrogen in carbon steels and outlines the influence of nitrogen in steels containing nitrogen binding elements such as aluminium, titanium, niobium and vanadium. The strong differences in the effectiveness of the four nitrogen binding elements are highlighted. The review will also address issues related to the unaffected base metal, the heat affected zone, and fusion zone. The implications of the literature review findings on current standards that restrict nitrogen in V microalloyed steels is also discussed.