Effects of martensite development on lattice strain evolution during the in situ deformation of austenitic stainless steels at cryogenic temperatures

The effects of martensite development on lattice strain evolution during the in situ compression of austenitic stainless steels, Type 304L, at ambient and cryogenic temperatures were investigated. Engin-X neutron diffractometer was used to study the change in the lattice strain during the uniaxial compression to 10% strain in situ. The report found no evidence of martensite during the compression test at ambient temperature. Similarly, no martensite was observed at cryogenic temperatures up to the applied load of 200 MPa in the elastic region. Martensite was only observed during the plastic deformation at cryogenic temperatures up to the applied strain of 10%. The presence of martensite in the austenitic stainless steels microstructure reinforces the austenite matrix. This was evident from the decrease in the lattice strain as the deformation temperature decreases. © IMechE 2013

Effect of temperature on the level of corrosion caused by heavy petroleum on AISI 304 and AISI 444 stainless steel

This work presents a study on the influence of national heavy petroleum in the corrosion of the AISI 444 and AISI 304 stainless steels in simulated refining operation conditions. The petroleum was first characterized through physicochemical analysis (density, fluidity point, viscosity, sulfur concentration). In an attempt to understand the corrosion effect of temperature and of the type of heating the referred types of steel thermal treatments were carried out at three levels of temperature (200, 300 and 400 °C). The procedure was done in conditions close to those in the distillation column. Heat was gradually increased from room temperature, and directly heated to working temperature. Each treatment took 4 hours to be completed. Scanning electronic microscopy (SEM) and the analysis of X rays dispersive energy (EDX) were used after the trials to characterize the samples. The results show that treatment temperature, as well as the type of heating, has distinct influences on each type of steel