Silicon Solid Solution Hardening
Silicon solid solution hardening increases the hardness and tensile strength of steels through dissolved silicon atoms in the lattice. It also improves scale resistance and electrical resistivity.
Physical-Chemical Mechanism of Action
Silicon solid-solution hardening occurs when silicon atoms dissolve into the metal lattice. These atoms distort the lattice during deformation, hindering the movement of free electrons and atomic cores, which increases hardness.
Metallurgical Relevance & Risks in Welding
Silicon solid-solution hardening improves the mechanical properties of steel, making it harder and stronger. But this can also cause problems, like increased stress buildup and possible hot cracking if cooling isn't adequate. Also, too much silicon can lead to fusion issues.
Shop Practice & Action Points
To take advantage of silicon solid-solution hardening, watch the cooling after welding. Avoid too fast cooling rates (t8/5 < 5 s), because that can create glass-hard martensite and increase cracking risk. At high silicon levels (above 0.40 %), you need a special cooling strategy to avoid fusion problems.