Investigations have been made on the effects of alloying (carbon, molybdenum and nickel) on the grain boundary segregation of phosphorus and on the phosphorus-induced intergranular fracture (IGF) in alpha -iron. The degree of phosphorus segregation is decreased by the addition of carbon through the site competition mechanism, but is unaffected by molybdenum and nickel as far as the alloying elements are in the solid solution. These results with molybdenum and nickel disagree with the current consideration for the role of these elements in the temper-embrittlement in low alloy steels. Carbon prevents IGF and increases the toughness of iron containing phosphorus by decreasing the phosphorus segregation and by increasing the grain boundary cohesion of iron independently of phosphorus. Molybdenum also prevents IGF and increases the toughness. This effect is due to the interaction of molybdenum with phosphorus at grain boundaries to decrease the effect of phosphorus.
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|Published - 1986