Effect of Melt-In and Key-Hole Modes on the Structure and Mechanical Properties of AISI 430 Steel Welded Using Plasma Transfer Arc Welding

Abstract

In this study, AISI 430 stainless steel couple 10 mm thick were welded in the butt position by melt-in and key-hole plasma transfer arc welding (PTAW) processes without using any filler wire addition and pretreatment. Welded joints were manufactured choosing a constant nozzle diameter (2.4 mm), welding speed (0.01 m/min), shielding gas flow rate (25 L/min), two different plasma gas flow rates (0.8 and 1.2 L/min), three different welding currents in melt-in PTAW process (80, 85 and 90 A), and three current intensities of the key-hole PTAW process (120, 125, and 130 A). In order to determine the microstructural changes that occurred, the interface regions of the welded samples were examined by scanning electron microscopy (SEM), optic microscopy (OM), X-ray diffraction (XRD) after PTAW. Microhardness and V-notch impact tests were applied to determine the mechanical properties of the welded samples. In addition, fracture surface were examined by SEM after impact tests.