Does anyone know the effects of Si and Ni contents on the mechanical properties (strength, impact and creep properties of 9Cr heat resistant steel weld metal?
Thank you.
Hi, the addition of Ni, normally results in the retardation of the creep onset due to the formation of Ni-Cr carbides, since these carbides are fine in their nature. their pinning mechanism near the austenitic grain boundaries may also cause a retardation in the recovery of martensitic microstructure of this alloy during welding. I think, it may have the same effect on the strength and impact toughness.
The added Silicon (Si) will help as it is a basically a deoxidizer and degasifier. In fact, It increases tensile strength and yield strength and moreover the hardness, and magnetic permeability. As far as clarity is concerned, Silicon helps to purify the iron ore during the smelting process because of the deoxidization and thus removing other kinds of impurities from it. Also, the Excess addition of Si may also improve the creep resistance and ductility of the steel. In welding, silicon is detrimental to surface quality in the low carbon like metals. It actually aggravates cracking effects when the carbon content is high. Slicon content if not exceed 0.10% welds are good including impact strength.
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