Molybdenum carbide stability
Molybdenum carbide stability is the thermal resistance of molybdenum carbides against coarsening at high temperatures. This ensures the creep resistance of hot-work and boiler steels.
Physical-Chemical Mechanism of Action
Molybdenum carbide stability refers to the ability of molybdenum carbides (Mo2C) in certain steels to resist coarsening at elevated temperatures. This stability comes from a stable chemical bond between molybdenum and carbon.
Metallurgical Relevance & Welding Risks
Coarsening of molybdenum carbides reduces creep resistance, which shortens the life of hot-work and boiler steels. If stability is lacking, cracks or creep can form in the weld zones, making the material unreliable.
Shop Practice & Action Items
To ensure molybdenum carbide stability when welding hot-work and boiler steels, do the following:
1 Use suitable filler materials with stable molybdenum carbides.
2 Hold the weld at the specified temperatures and times to get the right cooling cycle (t8/5 between 10 and 30 seconds).
3 Avoid excessive welding temperatures that could cause rapid cooling or severe coarsening.