The thermomechanical working of carbon steel

Abstract

1. Plastic deformation of stable austenite with limitation of the development of recrystallization, provides strengthening of the final structure in all forms of transformation-martensitic, intermediate, and pearlitic. 2. The strengthening effect is different with different forms of transformation in eutectic carbon steel. Strengthening as the result of deformation is a maximum in the martensitic transformation, with the tensile strength increasing 30% and the ductility dropping by half; a minimum in the pearlitic transformation, with an increase in ductility of 20% and in strength of 15–20%; and with an intermediate value for intermediate transformation, an increase in strength of 20% and in ductility also of 20%. 3. The maximum strengthening is obtained with an austenite deformation of 25–35% for the martensitic transformation; of 15–20% for the intermediate transformation; and of 6–8% for the pearlitic transformation. 4. As a result of changes in the fine structure of the strengthened steel the addition of a small quantity of titanium provides high ductility. 5. The desirability of using particular methods of treating eutectic carbon steel, such as high temperature thermomechanical working, high temperature thermomechanical working with isothermal transformation, and high temperature thermomechanical working with diffusion transformation, is determined by the dimensions of the starting piece, service conditions, and production conditions.