THE EFFECT OF EXPLOSIVE LOADING ON THE MICROSTRUCTURE OF SOME METALS AND ALLOYS

The effects of explosive pulses on the microstructure of Al-4. 5%Cu duralumin, tough pitch copper, pure magnetic iron and 18 chromium 8 nickel stainless steel have been studied using transmission electron microscopy. In copper and duralumin it was found that the microhardness increased with the duration of the rarefaction flank. The size of the shock transformed alpha prime martensite particles in stainless steel also increased with rarefaction time. Three wave interactions could be related to the microstructure of baratol-loaded iron and were attributed to the double shock front caused by the alpha to epsilon phase transformation. The microstructure of shocked stainless steel showed that hexagonal epsilon plates and gamma twins could occur in the same grain and that alpha prime martensite particles were formed at the intersection of two gamma twins, or of epsilon plates and gamma twins. The short rise and fall times in the pulse flanks made it possible to discuss formation mechanisms for twins and alpha prime martensite particles in terms of the available formation times.