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Ishapore, India

Bandyopadhyay P.S.,Ordnance Development Center | Ghosh S.K.,Bengal Engineering and Science University | Kundu S.,Bengal Engineering and Science University | Chatterjee S.,Bengal Engineering and Science University
Materials Chemistry and Physics | Year: 2013

A new low carbon titanium and niobium microalloyed steel has been thermomechanically processed in a pilot plant unit. Phase transformation phenomenon of the above steel during continuous cooling has been assessed. Evolution of microstructure and mechanical properties has also been studied at different finish rolling temperatures. A mixture of intragranular ferrite with granular bainite and bainitic ferrite along with inter-lath and intra-lath precipitation of (Ti, Nb)CN particles are the characteristic microstructural feature of air cooled steel. However, mixture of lower bainite and lath martensitic structure along with similar type (Ti, Nb)CN precipitate is observed in water quenched steel. High yield strength (896-948 MPa) with high tensile strength (974-1013 MPa) has been achieved with moderate ductility (16-17%) for the selected range of finish rolling temperature for air cooled steel. However, the water quenched steel yields higher yield strength (1240-1260 MPa) as well as higher tensile strength (1270-1285 MPa) but with lower ductility (13-14%) for the selected range of finish rolling temperature. Fairly good impact toughness values in the range of 50-89 J are obtained for the air cooled steel which are marginally higher than those of water quenched steel (42-81 J). © 2012 Elsevier B.V. All rights reserved. Source


Chatterjee S.,Bengal Engineering and Science University | Ghosh S.K.,Bengal Engineering and Science University | Bandyopadhyay P.S.,Ordnance Development Center
Advanced Materials Research | Year: 2014

A low-carbon, titanium and niobium (Ti-Nb) bearing and a low-carbon titanium, niobium and copper (Ti-Nb-Cu) bearing ultra high strength steel have been thermo-mechanically processed on a laboratory scale unit. Evolution of microstructure and mechanical properties of the above air cooled steels have been studied at different finish rolling temperatures (FRTs). Microstructural characterization reveals largely a mixture of granular bainite and bainitic ferrite along with the precipitation of microalloying carbide/carbonitride particles and/or Cu-rich precipitates. (Ti-Nb) bearing steel yields higher yield strength (1114-1143 MPa) along with higher tensile strength (1591-1688 MPa) and moderate ductility (12-13%) as compared to (Ti-Nb-Cu) bearing steel having yield strength (934-996 MPa) combined with tensile strength (1434-1464 MPa) and similar ductility (13%) for the selected range of 850-750°C FRT. Due to higher strength-ductility combinations, these present investigated steels can be regarded as the replacement material for ballistic applications as well as other sectors like defense, pipeline, cars, pressure vessels, ships, offshore platforms, aircraft undercarriages and rocket motor casings etc. © (2014) Trans Tech Publications, Switzerland. Source


Bandyopadhyay P.S.,Ordnance Development Center | Kundu S.,Bengal Engineering and Science University | Ghosh S.K.,Bengal Engineering and Science University | Chatterjee S.,Bengal Engineering and Science University
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

The current study concerns the development of a low-carbon, microalloyed ultra-high-strength steel on a pilot scale. The continuous cooling transformation has been evaluated, and a flat top "C" curve with a mixed microstructure of bainite and martensite has been obtained at a lower transformation temperature. The steel has been processed thermomechanically, followed by air cooling and water quenching. In addition, a variation in microstructure and mechanical properties at different finish rolling temperatures has been studied. Although a mixture of granular bainite and bainitic ferrite with interlath and intralath precipitation of NbC/NbC(N)/TiC(N) particles are the characteristic microstructural feature of air-cooled steel, the lath martensitic structure along the fine NbC/NbC(N)/TiC(N) precipitate is obtained in case of a water-quenched steel. The high-strength value obtained in the current steel is caused by the accumulated contribution of fine-grained, pancaked austenite, highly dislocated fine lath martensitic structure along with the presence of tiny precipitates of microalloy carbide/carbonitride. © 2010 The Minerals, Metals & Materials Society and ASM International. Source


Ghosh S.K.,Bengal Engineering and Science University | Bandyopadhyay P.S.,Ordnance Development Center | Kundu S.,Bengal Engineering and Science University | Chatterjee S.,Bengal Engineering and Science University
Materials Science and Engineering A | Year: 2011

In the present study, copper bearing low carbon microalloyed ultrahigh strength steel has been produced on a pilot scale. Transformation of the aforesaid steel during continuous cooling has been evaluated. The steel sample has been thermomechanically processed followed by either air cooling or water quenching. Variation in microstructure and mechanical properties at different finish rolling temperatures has been studied. A mixture of granular bainite, bainitic ferrite and precipitation of nano-sized (Ti, Nb)C particles is the characteristic microstructural feature of air cooled steel. On the other hand, predominantly lath martensitic structure along with the similar type of microalloying precipitates of air cooled steels and Cu precipitates are obtained in case of water quenched steel. The best combination of strength (1364-1403. MPa) and ductility (11-14%) has been achieved for the selected range of finish rolling temperature of water quenched steel. © 2011 Elsevier B.V. Source


Bandyopadhyay P.S.,Ordnance Development Center | Ghosh S.K.,Bengal Engineering and Science University | Kundu S.,Bengal Engineering and Science University | Chatterjee S.,Bengal Engineering and Science University
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

In the present study, low carbon microalloyed ultrahigh-strength steel was manufactured on a pilot scale. Transformation of the aforesaid steel during continuous cooling was assessed. The steel sample was thermomechanically processed followed by air cooling and water quenching. Variation in microstructure and mechanical properties at different finish rolling temperatures (FRTs) was studied. A mixture of granular bainite and bainitic ferrite along with interlath and intralath precipitation of (Ti, Nb)CN particles is the characteristic microstructural feature of air-cooled steel. On the other hand, lath martensitic structure along with a similar type of microalloying precipitates of air-cooled steels is obtained in the case of water-quenched steel also. The best combination of strength (1440 to 1538 MPa) and ductility (11 to 16 pct) was achieved for the selected range of FRTs of water-quenched steel. © The Minerals, Metals & Materials Society and ASM International 2011. Source

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