Tensile and Ball Indentation Response of Am350 Steel at Room Temperature

AM350 is precipitation-hardened stainless steel which is widely used as the material of construction for welded disk bellows in nuclear and aerospace applications. Development of welded disk bellows of AM350 for nuclear applications is being carried out. The bellows are manufactured with 0.3 mm thick AM350 sheets in the solution annealed condition (AM350-SA). Before deploying in service, the bellows are heat-treated to sub-cooled and tempered (SCT1000) condition for improving the mechanical strength. The paper discusses the tensile response of AM350 in the solution annealed (AM350-SA) and precipitation-hardened (SCT1000) conditions, based on uniaxial tensile tests conducted on 0.3 mm thick sheets. The hardness and yield strength of AM350 in the SCT1000 condition was found to be high compared to that of AM350-SA, though the ductility in the former was found to be less. However, the ultimate tensile strength of AM350-SA is comparable with that of AM350-SCT1000. The indentation load-depth response of the material was obtained experimentally in automated ball indentation (ABI) testing was also predicted numerically by elastoplastic finite element (FE) analysis. The data obtained from the tensile test was used as the input for the FE analysis. For both the material conditions, a close agreement between the numerically predicted and experimental ABI responses of the material is observed that validated the applicability of uniaxial tensile data to the prediction of indentation load-depth response.