Weldability of a Low Carbon High Strength Ti-Containing Bainitic Steel Produced by CSP
The weldability of a 700 MPa grade low carbon Ti-containing microalloyed bainitic steel produced by compact strip production (CSP) has been investigated by gas metal arc welding. Microstructural features of the welded joint of the investigated steel have been investigated utilizing optical and scanning electron microscopy (SEM). The microstructures in the heat affected zone (HAZ) consist of a predominantly bainitic ferrite and a proportion of acicular ferrite which formed on Ti-oxide and/or nitride particles. The acicular ferrite formed earlier effectively partitions prior austenite grains into smaller separate regions. The bainite transformed at lower temperatures is thus restricted in the smaller regions so that fine-grained mixed microstructures are obtained. The superior toughness of the weld joint of the investigated steel is attributed to the prior formation of acicular ferrite in the heat-affected zone.
Y. Akiniwa, K. Akita and H. Suzuki
R. Wei et al., "Weldability of a Low Carbon High Strength Ti-Containing Bainitic Steel Produced by CSP", Materials Science Forum, Vol. 652, pp. 275-278, 2010