Structure and properties of high-temperature austenitic low-carbon 01Kh15N22AG2V4TYu and 02Kh18N12AG11MFB steels

Principles of multicomponent alloying of high-temperature steels are formulated on the basis of reported and obtained experimental data. The short- and long-term strength, the structure, and the phase composition of high-temperature austenitic low-carbon steels 01Kh15N22AG2V4TYu and 02Kh18N12AG11MFB are studied in the structural states that form upon forging and aging and ensure the maximum hardening. These steels are found to have a high short-term strength and high-temperature strength. The tests of these steels performed for 8 × 10³ h without failure of specimens at a temperature of 680°C and stresses of 100–120 MPa show that they are promising materials that can operate at 620–680°C for 2 × 10⁵ h at a stress of 70 MPa in power units intended for operation at supercritical vapor parameters. The specific features of the fine structures of the steels in the forged and aged states that provide their high high-temperature strength are revealed. The evolution of structural constituents during long-term strength tests is studied, and the role of these constituents in fracture is determined.