Volume 11 Issue 1 ( March )

The high chrome heat-resistant steel is commonly used as a part of an ultrasupercritical steam boiler and creep failures are usually observed after the part has been exposed to constant high boiler temperature operation. The heat-resistant steel 253 MA which contains high chrome of about 22 wt.% is usually found to be used for steam boiler pipe, so as it is interesting to investigate and evaluate the behavior of creep rupture of this steel and the relationship with microstructure and mechanical properties. The 253 MA heat-resistant steel material was cut and deformed using cold rolling to about 35% thickness reduction and heated at temperatures constant of 900, 1000, 1100 and 1200 ℃ for 0, 240, 420, 840, and 3600 seconds at each temperature under heating rate of 10 ℃/minutes and then quenched. Another high chrome heat-resistant steel 316L is also used as an investigated steel for validation of the austenite grain growth. The creep rupture test was carried out at a temperature of 700 ℃ and a stress of 150 MPa. The result of this study is evaluated as a modified model which describes the relationship of the Larson-Miller parameters between hardness and austenitic grain size, and it is found that the modified model seems to be in close agreement with another high chrome steel which has been reported in previous work.

Keywords: creep resistant; time of rupture; grain size; hardness; high chrome; heat resistant steel; empirical model