What Are Steel Metalworking Processes – Hot Forming, Cold Forming & Warm Forming

Steel metalworking processes are imperative in forming the casted steel ingots or billets into various shapes and components. Metalworking is the shaping of the steel into desired products with increased strength and toughness. Hot forming, cold forming and warm forming are the most common types of metalworking processes used in forming steel. 

Hot Forming

Hot forming processes apply heat to soft in the metal for shaping with pressure, these processes include hot rolling, hot forging and hot extrusion. 

– Hot rolling involves passing heated slabs of metal through rollers to reduce the size of the bar or slab. This process rolls a short thick product to create a longer thinner product. This process is performed at a hot rolling mill and is utilized on products that do not normally require exact tolerances. 

– Hot forging also simply referred to as forging, is the process of deforming metal at high temperatures with any press or hammer. Hot forging can be used to manufacture small and precise parts as well as a variety of long product shapes. 

– Hot extrusion is the process of pushing a hot steel blank or workpiece through a die of a desired cross-section, that will reduce the cross section of the extruded piece. The extruded piece will have the same cross-section or shape throughout the whole piece and will contain an elongated grain structure. 

Cold Forming

Cold forming processes form steel at room temperature and do not require heating of the metal. These processes include cold rolling, cold forging and cold drawing. 

– Cold rolling is the process of compressing metal at room temperature between rollers to reduce the thickness of the metal. This process is completed on a cold rolling mill and is performed on products that were hot rolled. The cold rolling processes provide a better surface finish with better control of exact dimensions. 

– Cold forging is the process of utilizing high speed and pressure to permit and accurately deform metal below the recrystallization points or at room temperature using a cold forging press. There is little or no waste generated during this process. However, cold forgings will not deform as readily as hot or warm forgings.

– Cold drawing is the process of pulling a raw bar or rod through a die to reduce the cross section of the raw stock while increasing the length of the original product. This process is performed without preheating and creates applications with elongated grains and improved mechanical properties. 

Warm Forging

Warm forging is defined as a process in which metal is deformed below the recrystallization point. Warm forging does not generate much scale formation on the part surface. Therefore, it is a more cost-effective process than hot forging. However, warm forging is limited to forming simpler shapes when compared to hot forging due to the ductility of the reheated steel.