Study on the enhancement of high-temperature performance of hot isostatic pressing thin-walled capsule based on weld material selection

Abstract

Hot isostatic pressing (HIP) is a powder metallurgy process used to manufacture high-performance parts, in which the capsule plays the role of driving powder densification. While the physical properties of the capsule itself lead to the phenomenon of insufficient and non-uniform localized heat and pressure transfer, thinning of the capsule becomes an important solution. Inevitably, capsule wall thinning will bring the risk of failure, especially at welded joints, so the quality control of the capsule is crucial. In order to achieve joint quality enhancement, this paper investigates the laser arc composite welding head used in the HIP process, which uses stainless steel wires in the welding of mild steel plates. The results show that the heat-affected zone of welded joints is characterized by the susceptibility to high-temperature plastic loss, which will become a potential risk during capsule operation. Furthermore, it has been demonstrated that thinner plates are more susceptible to the effects of welding action. The resultant welding stresses have the potential to compromise the capsule's capacity to regulate shape, and may precipitate high-temperature plastic loss. In light of these findings, this paper proposes a solution that involves replacing the heterogeneous weld with a homogeneous weld. This modification is expected to universally weaken the welding stress from the welding principle. Furthermore, the introduction of an equal-strength matching method between the weld and the base material is anticipated to result in the involvement of the weld region in the deformation process when high-temperature plastic loss occurs in the heat-affected zone. This, in turn, is expected to inhibit the occurrence of brittle fracture and thereby strengthen the welded joint.