The Effect of Grain Size and Retained Austenite on the Ductile-Brittle Transition of a Titanium-Gettered Iron Alloy.

摘要

The effect of microstructural changes on the ductile-brittle transition temperature (DBTT) was studied in a titanium-gettered Fe-8Ni-2Mn-0.15Ti alloy. A fairly strong grain size dependence of the transition temperature was found. Grain size refinement from approximately 38micrometers (ASTM No. 6.5) to approximately 1.5micrometers (ASTM No. 15.5) through a four-step thermal treatment lowered the transition temperature by approximately 162C. A small amount of retained austenite was introduced to this grain-refined microstructure,and the transition temperature was suppressed by an additional 100approximately 150C. The suppression of the DBTT due to retained austenite was smaller when introduced into a large grained structure (approximately 64C). The distribution and stability of retained austenite were also studied.