Effect of hydroextrusion on the mechanical properties of TRIP-steels

The kinetics of cold hardening, resistance to cavitation and the damage pattern of a group of low-carbon austenitic steels Kh18N10T, 10Kh11N23T3MR(EhP33), N36, G38, 12Kh18N9T and martensitic steels N9, G17, SN2M have been studied on exposure to cavitation effects in liquid oxygen subcooled down to -196deg C at an excess hydrostatic pressure of 4 atm. Presented are the results of the mechanical test of austenitic steels in the hardened state (from 1150 deg C), steel 10Kh11N23T3MR being subjected to ageing at 750 deg C after hardening, martensitic steels in the hardened (from 740 to 800 deg C), and the tempered states (at 200 to 600 deg C), and also intermediate steel SN2AL subjected to hardening (from 1100 deg C) with a subsequent deep-freeze treatment at -70 deg C and tempering at 250 deg C. The cavitation-damaged surface has been examined by the electron microscopy technique. The higher low-temperature resistance of the steels to cavitation is associated primarily with the availability in their structure of an austenite unstable towards martensite transformation at low-temperature plastic deformation