THE EFFECT OF MANGANESE ON INTERGRANULAR FRACTURE IN LOW ALLOY STEELS

The grain boundary embrittlement of low alloy steels was studied, attention being paid to the effect of manganese concentration. The prior austenite grain boundary of tempered martensitic samples containing 0.5, 1.0, 1.5 wt% Mn were analyzed by AES. (1)Increasing bulk manganese content was found to cause a small increase in the amount of segregated phosphorus and a decrease in the amount of segregated carbon. (2)Measurements of internal friction (Snoek peak) showed that the addition of manganese lowered the concentration of dissolved carbon. Based on these facts, the embrittling effect of manganese can be explained by the decrease of the concentration of segregated carbon which strengthens grain boundaries