Induction Heat Treatment of Sheet‐Bulk Metal‐Formed Parts Assisted by Water–Air Spray Cooling

Abstract

In order to produce components with massive secondary functional elements from sheet metal bulk forming operations, termed sheet-bulk metal forming, can be applied. Owing to high, three-dimensional stress and strain states present during sheet-bulk metal forming, ductile damage occurs in the form of micro-voids. Depending on the material flow properties, tensile residual stresses can also be present in the components' formed functional elements. During service, the components are subjected to cyclic loading via these functional elements, and tensile residual stresses exert an unfavorable influence on crack initiation and crack growth, and therefore on the fatigue life. Following the forming process, temperature and microstructurally related compressive residual stresses can be induced by local heat treating of the surface. These residual stresses can counteract potential crack initiation on the surface or in the subsurface regions. In the present study, the adjustability of the residual stress state is investigated using a workpiece manufactured by orbital cold-forming, which possesses an accumulation of material in its edge region. Based on residual stress measurements in the workpiece's edge region using x-ray diffractometry, it is possible to verify the compressive residual stresses adjusted by varying the cooling conditions.

Wetting layer evolution and interfacial heat transfer in water-air spray cooling process of hot metallic surface

“…The spray cooling rate must be dynamically controlled to maintain competitiveness and continuously produce high-strength, high-quality steel at the highest productivity during continuous casting. Besserer et al [13] adopt orbital forming method to manufacture semi-finished parts which are used DP600 deep-drawing steel as the material, and perform surface heat treatment on parts. The results showed that a proper water-air spray cooling process could induce compressive stresses which is conductive to improve fatigue life.…”