Effect of Manganese on Low Temperature Toughness of Carbon-free 11Ni-1Mo Steels

Abstract

Effects of manganese on low temperature mechanical properties have been studied in carbon-free 11Ni-1Mo-Mn steels. Charpy impact tests were performed at temperatures between 0°and about -255°C. A manganese free steel revealed intergranular failure in the as-quenched condition, and the sulfur segregation to austenite grain boundaries may be responsible for this embrittlement. This phenomena could be easily eliminated by the addition of only 0.5 pct manganese. However, as the manganese content increased more intergranular embrittlement during reheating prevailed. The grain boundary segregation of nickel and manganese might be closely concerned with the mechanism of the embrittlement.
The fine-grained 0.5 pct manganese steel showed the most excellent low temperature toughness and revealed no brittle feature in Charpy tests at about -255°C when it was reheated at temperatures between 550°and 650°C.