Per: FLAVIA TEREZA DOS SANTOS FERNANDES TOLOMELLI (IME - INSTITUTO MILItar de engenharia), andersan dos santos paula (instituto militar de engenharia), fernando cosme rizzo assunção (puc-rj)
Abstract:
A comparative evaluation of two High Strength Low Alloy steels, regarding their ability for the quenching and partitioning (T&P) process, was performed. To carry out the study, the ThermoCalc program was used with a database in the TCFE9 version, which served as the basis for: determination of the composition of austenite in the intercritical field; determination of the equilibrium temperatures of phases that delimit the intercritical field (Ae1 and Ae3), and obtaining the precipitation maps of the referred alloys. With the aid of empirical equations, the onset temperatures of the bainitic and martensitic transformations (Bi and Mi) were determined, which were used as a basis for the performance of the one-stage quenching and partitioning heat treatments. The quenching heat treatments were carried out on a pilot scale in a muffle furnace with temperature monitoring and oil cooling. The ImageJ software was used for quantitative analysis of the alloys in order to have an estimate of the percentage of retained austenite present in the alloys (estimated as a function of the % of MA constituent). As a conclusion of the work, it was observed that alloy a, with additions of Mo-Ti-Nb-B (MA > 9%) compared to alloy b with additions of Cr-Mo-Nb-B (%MA < 8%) presented the higher values of total elongation indicating that this alloy has greater suitability for the T&P process.