Effect of molybdenum and temperature reduction on hot ductility of 0·2C–Mn steels

The influence of up to 0·4%Mo and temperature reduction before strain on the hot ductility of 0·2C–Mn–Al steels was investigated using a Gleeble 1500 thermal simulator. With the addition of 0·4%Mo, the ductility was reduced in the austenite temperature region because the precipitation of carbides was encouraged. However, ductility improved in the ferrite–austenite dual phase region because a solution of Mo in the ferrite reduces the difference between the strength of ferrite and austenite and results in a more homogeneous distribution of strain between the boundaries and the matrix. A temperature reduction introduced before straining seriously impaired ductility, especially when it resulted in γ–α phase transformation, owing to the enhanced precipitation of carbides.