Temperature and Strain Rate Effects on the Mechanical Behavior of Ferritic Stainless Steels

Abstract

To gain knowledge about the applicability of ferritic stainless steels in exhaust pipes and other high temperature applications, mechanical testing of EN 1.4509 (ASTM S43932) and EN 1.4521 (ASTM 444) was conducted at 600 °C and 800 °C. Tensile tests with short high temperature exposure were carried out to determine the material properties in the as-received condition. To study the high temperature service performance and the effects of possible microstructural changes during long-term high temperature exposure, tensile tests were performed for samples that had undergone a 120 h furnace heat treatment at 600 °C. As an example of the effect of exposure time, serrated flow was observed in the tests for as-received EN 1.4509, which indicates dynamic strain aging. The effect, however, disappeared after the 120 h heat treatment, suggesting that notable microstructural changes take place at high temperatures. Also fatigue and high strain rate tensile tests were conducted on the test materials to reveal the effects of high temperature exposure on their properties, microstructure and service performance.KeywordsFerriticHigh temperaturePrecipitationSteelStrain rate