The Effect of Strain Rate on Ultra-fine Grained Structure of Cold Drawn 304L Stainless Steel Wires

The effect of strain rate on nano structured and ultra-fine grained microstructure in austenitic stainless steel AISI 304L was investigated during cold wire drawing process. This process was used to produce strain induced martensite transformation and then samples were annealed to create reversion in examined material. Samples were subjected to two different strain rates of 0.41 and 1.032 s-1 with relatively heavy imposed cold drawing of 1.13 strain. Best condition of subsequent annealing were obtained from experiments which eventuated to ultra-fine grained austenitic structure with different sizes. Metallographic examination, X-ray diffraction and scanning electron microscopy have been used for microstructural characterizations. Finally a very fine structures were produced with average grain sizes of 441 nm and 415 nm by applying strain rates of 1.032 s-1 and for 0.41 s-1 respectively.