Hadfield Steel Precipitation Kinetics

Manganese hard steel tends to precipitate carbides in the heat-affected zone during welding. This happens when the material cools too slowly. These carbides make the steel hard and brittle, which can lead to cracks. You have to control the cooling so that the critical zone is passed through quickly enough. So cool down quickly, but without quenching the material abruptly. If you let the weld cool too slowly, the structure will become hard and you'll have problems.