THE EFFECT OF SHIELDING GAS COMPOSITION ON THE TOUGHNESS AND CRACK GROWTH PARAMETERS OF ALMG4,5MN WELD METALS

The experiment have been performed using samples of welded joints of the three components aluminium alloy AlMg4,5Mn. The welding was performed with GTAW in the shielded atmosphere of Ar+0,015N2, mixture of the inert gases Ar+50%He+0,015N2 and Ar+70%He+0,015N2. After welding has been completed, the metallographic tests, the tensile test and the tests of the hardness were performed. Also, the weld metal toughness was estimated, using the instrumental Charpy impact testing system, followed by estimating the crack initiation energy, crack growth energy and the fracture mechanics parameters. The goal was to establish the effects of shielding atmosphere composition on the mechanical properties and fracture mechanics parameters of weld metal