Influence of Cr on weld solidification cracking in Fe-15Mn-0.5C-3.5Al-xCr alloys

Abstract

The solidification cracking sensitivity of Fe-15Mn-0.5C-3.5Al-xCr (×= 5, 12 mass%) alloys was evaluated using a longitudinal Varestraint test and compared with that of austenitic Fe-18Mn-0.6C alloy. Weld microstructures of Low Cr (5 mass%) and High Cr (12 mass%) alloys revealed duplex structures with a mixture of austenite and δ ferrite. The amounts of residual δ ferrite and (Cr, Fe, Mn)23C6 carbide remarkably increased with increasing Cr content. A small amount of Cr addition (5 mass%) provided negligible influence on the solidification cracking susceptibility. However, the welds of high Cr alloys demonstrated excellent resistance to solidification cracking due to healing by the eutectic liquid. The addition of Cr enhanced the formation of a low melting point (γ + (Cr, Fe,Mn)7C3) eutectic during solidification by increasing the eutectic formation temperature and simultaneously decreasing the eutectic C content.