The carbon steel forgings need to be processed before forging, so the overheating phenomenon during the heating process means that the heating temperature of the metal billets used in the carbon steel forgings is too high, and the residence time is too long in the specified forging and heat treatment temperature range, or because The thermal effect causes coarse grain growth caused by excessive temperature rise.
The Wei steel structure appears after the carbon steel forgings are overheated. After the martensite steel is overheated, the intragranular texture tends to occur, and the tool steel is often characterized by the primary keratinization of the carbide. After the titanium alloy is overheated, there is a distinct β-phase grain boundary and a straight and slender Wei's structure. If the alloy steel is overheated, there will be a stone-like fracture or a strip fracture. Overheated tissue, due to coarse grains, will cause a decrease in mechanical properties, especially impact toughness.
In general forgings, after the normal heat treatment (normalizing, quenching) of the overheated carbon steel forgings, the structure can be improved and the performance is restored. This overheating is often called unstable overheating; and the alloy structural steel forgings are seriously overheated. After normal normalizing (including high temperature normalizing), annealing or quenching, the superheated structure cannot be completely eliminated. This overheating is often referred to as stable overheating.