THE PHASE CONVERSION IN STAINLESS STEEL UNDER LSW PROCESSING

The effect of thermal treatment, plastic deformation and laser shock waves on the phase transformation of austenitic stainless steel was studied by methods of gamma resonance spectroscopy and electrical resistance. There is a laser processing method known as LSW (laser shock waves in transparent condensed medium), which provides great surface compression and low plastic deformation and could be used for modification of material properties. The influence of laser shock waves in transparent condensed medium on phase conversion in stainless steel X18H10T is studied by Mossbauer spectroscopy and electroresistance methods. The shock waves were generated by impact of nanosecond laser pulses with power density q ~ 10(13) W/m2. It is shown that shock waves passage in this material causes martensite conversion and increases corrosion stability. Austenite obtained in such a way has increased corrosion stability in liquid lithium in comparison with austenite obtained after conventional thermal treatment. The formation of austenite by the shock waves mechanism is connected with two rival action factors: great (2 GPa) compression and low (~ 0,001) plastic deformation degree. The selective dissipation of LSW is the main factor which causes the cleaning of the grain border from the impurities and the homogenizing of structure. A similar effect of homogenization and ordering after LSW-treatment was observed in IV - VI semiconductors.