Comparative study of microstructure and properties of as received, heat treated and welded Mild steel bar (SRMB) and TMT bar (SRMB)

Abstract

India is among the fastest developing nation in the world with major constructions like bridges, dams, airports, residential buildings etc. In a developing economy where infrastructure is getting boom, strength of structural members is of great importance. This is where Thermo Mechanically Treated (TMT) bars scores over Cold twisted bars (or CTD bars). For understanding the proper behaviour of structural members, physical properties, chemical composition, mean projected rib area and macrostructure are very essential. Nowadays there are many companies which supply untreated and twisted deformed bars as TMT bars which would do much harm for structural stability. There is an urgent need to use the phrase “Quenching and Tempering” to label the TMT bars. This project is an effort to showcase the ways to identify good quality TMT bars. This thesis paper attempts to find variation of microstructure configuration of mild steel barandtmtbar (srmb) in metallography laboratory and Hardness variation of mild steel bar and tmt bar (srmb) from it’s core to peripheral region by VICKER’S Hardness test method micro hardness test method in our hardness test laboratory. We have tried to examine corrosion behavior of the samples in both fresh water and marine water via corrosion penetration method to determine the change of corrosion penetration rate with the change of salinity. It was attempted to heat treatment ( air cooling and quenching in water) to demonstrate the micro structural change(by metallography), hardness change(by VICKER’S hardness number) and corrosion behavior change(by corrosion penetration method).By observing the result we can make some comparison how their micro structural behavior ,hardness number and corrosion behavior changes with various temperature and climatic condition. At the last we have made attempt to examine the heat treated zone microstructure of welded tmt bar, how it changes from welding zone to head treated zone(HAZ) and heat treated zone(HAZ) to parent zone