Impact toughness of high strength low alloy TMT reinforcement ribbed bar

Abstract

Charpy V-notch impact toughness of 600 MPa yield stress TMT rebars alloyed with copper, phosphorus, chromium and molybdenum has been evaluated. Subsize Charpy specimens were machined from the rebar keeping the tempered martensite rim intact. The copper-phosphorus rebar showed toughness of 35 J at room temperature. The toughness of copper-molybdenum and copper-chromium rebars was 52 J. The lower toughness of phosphorus steel is attributed to solid solution strengthening and segregation of phosphorus to grain boundaries. Due to superior corrosion resistance, copper-phosphorus TMT rebar is a candidate material in the construction sector.

Hardened Case Properties and Tensile Behaviours of TMT Steel Bars

“…However, one should control the cooling rate of the surface area of the bar. As a standard practice, the surface temperature should be cooled to below 200°C within few seconds, whereas, the core temperature will remain nearly 800°C after leaving the water cooling chamber, Figure 8 [17,18]. If the above mentioned temperatures of different zones are achieved in the cooling chamber then, after about ten seconds, both the surface and core temperatures will be equalized to about 650°C on the cooling bed immediately after placing the steel bars over it.…”

“…For a very hard surface, notch sensitivity becomes severe. Surface roughness caused during the hot rolling and oxidation during heat treatment schedule on the steel bars might also act as a stress raiser [18]. Altogether, minor defects on the steel bars of excessive hardness/strength might cause shear type of failure.…”

Effect of Thermal Exposure on the Charpy Impact Properties of Thermo-Mechanically Treated Reinforcement Steel Bar

“…Thermo‐mechanically treated (TMT) rebar, is widely used in construction sector for the reinforcement of concrete structures in Indian subcontinent, Europe, and various parts of the world . Steel reinforcement withstands the high compressive load of the concrete structure and also provides flexibility to the structure .…”

“…Steel reinforcement withstands the high compressive load of the concrete structure and also provides flexibility to the structure . TMT rebars are generally made of plain C–Mn steel following “Tempcore” process, which develops a composite microstructure at the cross‐section comprised of ductile core made of ferrite‐pearlite, surrounded by harder rim made of tempered martensite . With the increase in urban population and extremity in weather condition, natural disasters like earthquake, cyclonic storm, blizzard, and man‐made disasters like explosions are increasingly becoming concern to the structural safety for avoiding human causalities and financial crisis.…”

“…Thermo-mechanically treated (TMT) rebar, is widely used in construction sector for the reinforcement of concrete structures in Indian subcontinent, Europe, and various parts of the world. [1][2][3][4][5] Steel reinforcement withstands the high compressive load of the concrete structure and also provides flexibility to the structure. [6] TMT rebars are generally made of plain C-Mn steel following "Tempcore" process, which develops a composite microstructure at the cross-section comprised of ductile core made of ferritepearlite, surrounded by harder rim made of tempered martensite.…”