Molybdenum effect on stainless steel

1. Influence on corrosion resistance of stainless steel

Molybdenum has synergistic effect with Cr, N and other elements, which can effectively inhibit pitting nucleation and development. Improve the resistance to local corrosion in reducing media, molybdenum can form molybdate (anode inhibitor), improve the corrosion resistance of stainless steel in reducing media (such as sulfuric acid, phosphoric acid, acetic acid, urea and some organic acids); Improved pitting resistance equivalent (PREN), as well as improved resistance to chloride ion local corrosion, molybdenum can enhance local corrosion resistance, especially in halide salts or seawater with chloride ions.

2. The impact on stainless steel organization

Molybdenum is an important ferrite forming element, which ensures phase balance in ferrite and duplex stainless steel. Molybdenum austenitic stainless steel needs to be matched to increase Ni, and N, in order to maintain the structure of austenite, and at the same time can be adjusted to inhibit or delay the precipitation of brittle phase.

3. The effect on the mechanical properties of stainless steel

Increasing the high temperature strength of austenitic steel can improve the high temperature strength, creep strength, lasting strength and high temperature fatigue properties, but the improvement of room temperature strength is not significant. And improve the strength and toughness of martensitic steel, increase the tempering stability and strengthen the secondary hardening to improve the strength, while not reducing the toughness.

4. The effect on stainless steel processing

Molybdenum has a solid solution strengthening effect, which increases the high temperature deformation resistance of steel, and the hot deformation is difficult; Due to the tendency of molybdenum segregation and the formation of harmful σ-equivalent intermetallic compounds, the thermoplasticity of steel is significantly deteriorated, and it is necessary to take a homogenizing heat treatment process to eliminate the precipitated phase.