Microstructural, mechanical and intergranular corrosion behavior of cold work and thermal ageing of low nickel austenitic stainless steel

In the present investigation, microstructural, mechanical and electrochemical properties of cold rolled Cr-Mn austenitic stainless steel were studied. Heat treatment (800 degrees C, 900 degrees C, 950 degrees C and 1000 degrees C) and thermal ageing (one, two and three hours) of surface were investigated using an optical microscope, scanning electron microscope. Mechanical characteristics like hardness and tensile strength were evaluated. Electrochemical test were carried out using double loop electrochemical potentio kinetic reactivation tests (DLEPR) for finding the degree of sensitivity (DOS). The results showed that without cold rolled, thermal aged for one, two and three hours, there was high sensitization at the temperature of 850 degrees C and 900 degrees C, but at the temperature of 950 degrees C and 1000 degrees C there was re-homogenization. The grain size increased with increase in temperature. With cold rolled samples, there was a reduction in grain size, increased in strength and hardness in the samples, which is due to the formations of strain induced martensite (SIM). With the increase in thermal duration (1, 2 and 3 h) there was an increase in martensite formation at temperature of 850 degrees C and 900 degrees C. At temperature of 950 degrees C and 1000 degrees C, work hardening diminished. Also, it was observed that increase in strain induces martensite which in turn increases degree of sensitization (% DOS).