Analysis of X5CrNi18-10 (AISI 304) Steel Susceptibility to Hot Cracking in Welded Joints Based on Determining the Range of High-Temperature Brittleness and the Nil-Strength Temperature

Abstract

The conducted research of X5CrNi18-10 (AISI 304) in the DSI Gleeble 3500 device aimed to determine the tensile strength of this steel at elevated temperatures, simulating welding-like conditions while sensitizing the steel to liquation cracking. The defined High-Temperature Brittleness Range (HTBR) made it possible to determine whether the material is susceptible to hot cracking, which can significantly affect the weldability of steel structures. The Nil-Strength Temperature (NST), with an average temperature of 1375 °C, was determined through a thermoplastic test, where the samples were pre-strained and subsequently heated. After the NST tests, no necking or plastic elongation of analyzed samples were noticed. The fracture of the samples was brittle at a low tensile force of 0.1 kN, indicating the value of NST (represents the upper limit of the HTBR). The lower limit of the HTBR (assumed to occur at a relative necking of 5%) was determined by heating samples to a temperature 5 °C lower than the NST and then cooling them to the specified temperature. Once the temperature was reached, the samples were subjected to tensile testing at that temperature, and the percentage necking (Z) and percentage elongation (A) were measured to determine the loss. This work indicates that the estimated Ductility Recovery Temperature (DRT) is slightly lower than 1350 °C, and X5CrNi18-10 (AISI 304) steel has a small HTBR, approximately 15 °C during heating and close to 25 °C during cooling, suggesting minimal tendencies to form hot cracks.