1972 Volume 36 Issue 9 Pages 897-902
The effect of thermomechanical treatment on the impact value at low temperature, hardness and tensile strength of modified 9% nickel steels containing various amounts of manganese, copper, molybdenum and niobium was investigated. By replacing nickel with manganese, the impact value decreased remarkably. Molybdenum was effective in enhancing the toughness by supressing temper-brittleness. Copper and niobium were effective for the strengthening, but their effects on the impact value were relatively small. Thermomechanical treatment showed remarkable effects upon increasing the strength and low temperature toughness. The major reasons were considered to be the refinement of structure and supressing temper-brittleness.