چكيده به لاتين
In this research, the effect of cold work on microstructure and mechanical properties of austenite stainless steel was evaluated by nominal composition Fe-14.2Cr-11.5Mn-0.3C. The effect of cold rolling in various amounts of 5, 20, 40 and %50 reduction in thicknesses was investigated on the austenite stability, plastic deformation mechanisms (glide, martensitic transformation and mechanical Twinning) and tensile properties. Then, the influence of reversion treatment was studied at the temperature of 1000°C for durations of 15, 60, 100, 180 and 300 seconds after % 50 cold rolling . Microstructural investigations were carried out using optical and scanning electron microscopy. In order to measure the magnetic phas and identify the phases in the microstructure, a feritscope instrument and x-ray diffraction analysis was used, respectively. Mechanical properties were investigated by tension test at ambient temperature.
Results showed that low stacking fault energy in this steel results in the formation of stacking faults and martensitic transformation, which increases the strength and work hardening rate.
The stages of deformation induced martensitic transformation is γ→ε→αˊ , respectively.
So that, with increasing the percentage of cold work, the amount of ε martensite decreases and αˊ martensite increases. The highest amount of martensite was taken in the % 50 cold rolled sample , as a result of reversion treatment of martensite to austenite was carried out in this sample at temperature of 1000 °C for 15 to 300 sec. Annealing of 50% cold rolled sample at 1000 ° C for 100 seconds resulted in fine-grained microstructure production with an average grain size of 12.6 µm. The yield strength, tensile strength and elongation was changed from 411MPa, 110MPa and %35 in solution annealing sample to values of 605MPa, 1300MPa and %32 in reversion annealed sample, respectively.
Keywords: Austenite stainless steel, Cold rolling, Martensitic transformation, reversion treatment
