The effect of weld head input on rehaz (reheated heat affected zone) of boron alloyed steel's mechanical properties and microstructure

Boron-alloyed steels are widely used in industry due to their high yield strength, impact toughness or hard-wearing structures. These steels have low carbon equivalents and have high weldability. This type of steel properties during the production process is gained by heat treatment and fine-grained steel as the welding process has been adversely affected properties. Especially in the multi-pass welding of thick parts, the loss of mechanical properties in the area affected by the heat will be higher. In this study, boron alloyed Dillidur 400 steel, which is made of abrasive parts due to its high abrasion resistance and Weldox 690 steel with high yield strength and toughness was investigated. Different welding speeds were selected to obtain different heat inputs. The welding current is kept constant and the welding heat is adjusted by the changes made in the welding speed. The welded seams are made parallel to each other in the form of blind passes. Heat addected zone and re-heat affected zone the internal structures of the heat affected regions, grain boundary precipitations and hardness were investigated.