Effect of Heat Input on the Tribological Behaviour of Wire Arc Additively Manufactured Duplex Stainless Steel 2209: Correlation with Acoustic Emission During Deposition

Duplex stainless steel 2209 is widely used in marine, oil and gas, and chemical process industries due to its exceptional tribo-corrosion resistance, which is significantly determined by its dual-phase ferrite-austenite microstructure. Gas Metal Arc Welding (GMAW) based Wire Arc Additive Manufacturing (WAAM) is a metal additive manufacturing technique for producing large-scale metallic components. This process enables the fabrication of component with required properties such as microstructure, surface hardness and wear resistance, etc. making it suitable for engineering applications. In this study, acoustic emission monitoring was integrated with reciprocating wear analysis to establish a process-structure-tribology relationship for WAAM deposits fabricated at heat inputs between 216.75 and 450.18 J/mm. The specimens extracted from the stabilized layers exhibited good microhardness values in the range of 291–316 HV, which are comparable to those reported for wrought DSS 2209 alloy. These results suggest that the WAAM-fabricated material can achieve mechanical performance comparable to the conventionally manufactured alloy, while friction parameters such as mean coefficient of friction, standard deviation, and forward–reverse asymmetry revealed strong dependence on deposition stability. The experimental specimens were cuboidal samples extracted from a GMAW-WAAM–fabricated block of DSS 2209 alloy produced at varying heat inputs. Tribological tests were conducted on a UMT Tribolab system under dry sliding conditions, using 100Cr6 hardened chrome steel balls with a diameter of 4.178 mm as the counter body. Measurements were performed at a load of 20N for a period of 30 min. The study highlights the influence of heat input on wear and frictional behaviour of WAAM-processed DSS 2209 and establishes a correlation between acoustic emission signals recorded during WAAM deposition and the resulting tribological performance of duplex stainless steel.