Weldability of Abrasion-Resistant Steels of 450 HB Hardness

Abrasion-resistant steels of 450 HB hardness combine carbon and alloying elements addition aiming a completely martensitic microstructure and high hardness by all thickness of the plate. But due this combination, generally represented by carbon equivalent, these steels present a difficult weldability. The aim of this work was evaluate the weldability of two abrasion-resistant steels of 450 HB hardness, both with different carbon equivalent and thickness. It was conducted Tekken test to evaluate the susceptibility to cold cracking induced by hydrogen and to determinate preheating temperature for welding. Besides that, welded joints using automatic MIG/MAG welding process with different heat inputs were manufactured. The welded joints were characterized by metallographic analyses and by mechanical tests. It was verified that both steels do not need preheating temperature. It was noted that the welded joints from steel with smaller carbon equivalent presented better results in the bending test, principally when used the higher heat input. This steel still presented bigger absorbed energy from the CharpyV impact test.