Deformation behaviour and material properties of austenitic heat-resistant steel X15CrNiSi25-20 subjected to high temperatures and creep

• Determination and analysis of material mechanical properties.
• Analysis of material creep resistance.
• Temperature dependence of material properties.
• Determination of Charpy impact energy and fracture toughness assessment.

This paper presents experimental results and analysis of the behaviour of heat-resistant austenitic steel (X15CrNiSi25-20) subjected to uniaxial stress at room and high temperatures. The results include stress–strain diagrams as well as creep curves showing the behaviour of material responses to different temperatures. The experimental results of Charpy impact energies provide the ability to asses fracture toughness. On the basis of stress–strain diagrams it is possible to determine ultimate tensile strength, yield strength, modulus of elasticity and total elongation. Also, from creep curves it is possible to analyse material’s resistance to creep at considered temperatures. Descriptive error bars relating to mechanical properties are also presented. Finally, the dependence of mechanical properties on strain rate is shown. Experimental results show that this steel is characterised by both high ultimate tensile strength (688 MPa/20 °C; 142 MPa/800 °C) and yield strength (498 MPa/20 °C; 132 MPa/800 °C) throughout the range of the investigated temperature field. Its creep resistance at temperatures of 500 °C and 600 °C may be treated as good if stress levels do not exceed: 280 MPa/500 °C and 130 MPa/600 °C.