Physical, Chemical and Mechanical Properties of Molybdenum in Steel

Molybdenum is a silver white metal. It is located in the fifth cycle and the ViB family of Mendeleev periodic table, which is a transitional element. The density of molybdenum is 10.23g/cm3, the atomic number is 42, and the atomic weight is 95.95. Molybdenum has a very high melting point, ranking sixth in the natural substance, which is called refractory metal. Molybdenum is often used in some metal materials. Like steel. So what is the effect of adding molybdenum to steel?

Next, we will analyze the microstructure, heat treatment, mechanical properties, physics, chemistry, process performance, etc. the role of molybdenum in steel:

1、 Effect of molybdenum on Microstructure and heat treatment of steel
1) Molybdenum is soluble in ferrite, austenite and carbide in steel, which is the element to reduce austenite phase area.

2) When the content of molybdenum is low, a composite cementite is formed with iron and carbon. When the content is high, a special carbide of molybdenum is formed.

3) The hardenability of steel can be improved by molybdenum, which is stronger than chromium, but weaker than manganese.

4) Molybdenum can improve the tempering stability of steel. As a single alloy element, the temper brittleness of steel is increased; when coexisting with chromium and manganese, the temper brittleness caused by other elements is reduced or restrained by molybdenum.

2、 Effect of molybdenum on mechanical properties of steel
1) Molybdenum has a solution strengthening effect on ferrite, at the same time, it also improves the stability of carbide, so as to improve the strength of steel.

2) Molybdenum can improve the ductility, toughness and wear resistance of steel.

3) Because molybdenum increases the softening temperature and recrystallization temperature after deformation strengthening, and greatly improves the creep resistance of ferrite, it can effectively inhibit the aggregation of cementite at 450 ~ 600 ℃ and promote the precipitation of special carbide, so it becomes the most effective alloying element to improve the thermal strength of steel.

3、 Effect of molybdenum on physical, chemical and technological properties of steel
1) When the mass fraction of molybdenum is more than 3%, the oxidation resistance of steel deteriorates.

2) The steel with Mo content less than 8% can still be forged and rolled, but with higher Mo content, the deformation resistance of steel to hot working increases.

3) Molybdenum can improve corrosion resistance of steel and prevent pitting corrosion of steel in chloride solution.

4) In the magnetic steel with 1.5% carbon and 2% - 3% molybdenum, the residual magnetic induction and coercive force can be increased.

4、 Application of molybdenum in steel
1) In many cases, Cr Mo steel can replace Cr Ni steel to make important parts, which is often used to make some high temperature and high pressure resistant valves and pressure vessels.

2) It is widely used in quenched and tempered and carburized structural steel, spring steel, bearing steel, tool steel, stainless and acid resistant steel, heat-resistant steel and magnetic steel.