Thermal stability of retained austenite in Cr–Ni weld metals at low temperatures

Abstract

As environmental temperature decreases, the amount of retained austenite is more likely to greatly reduce due to the thermal austenite-martensite transformation caused by the decreased thermal stability of retained austenite, probably making its amount lower than the required content. In the present study, the thermal stability of retained austenite in Cr-Ni weld metals was investigated to see whether sufficient retained austenite can be maintained at low temperatures. The specific experimental procedure is as follows: briefly, the samples were cooled in turn from room temperature to 0, 220, 240, 260, 280, 2100 and 2196uC; the amount of retained austenite at the above temperatures was measured using X-ray diffraction. Through investigating the dependence of the content of retained austenite on temperature, it was revealed that when the content of retained austenite is ,20%, retained austenite can be maintained until 2196uC.

Impact behavior of 980 MPa grade Cr-Ni weld metal composed of martensite and retained austenite

“…When applied strain imposes on it, it will transform into martensite. As an accompanied research of the present study, the mechanical 16) and thermal stability 16) of the retained austenite have been investigated in detail. It has been shown that the retained austenite enhances the tensile properties 11， 12) and fracture toughness 13) through the strain-induced marteniste transformation from it.…”

Mechanical Stability of Retained Austenite in Multi-Pass Cr-Ni Weld Metal in an Over-Matching Welded Joint

“…The thermal stability of retained austenite in the Cr-Ni weld metal has been investigated elsewhere. 12) It was found that if the initial content of retained austenite is less than 20%, even if the service temperature reduces from 25 C to −196 C, its amount remains constant. This demonstrates that within the temperature range of 25 C to −196 C, temperature variation does not affect the amount of retained austenite when its initial amount is less than 20%.…”