Vineet Bajaj - Academia.edu (original) (raw)

Papers by Vineet Bajaj

Materials Today: Proceedings, 2019

The main objective of the current investigation is to achieve strengthening of SA210 Grade A1 boi... more The main objective of the current investigation is to achieve strengthening of SA210 Grade A1 boiler steel using friction stir processed (FSPed) using pinless WC tool with plunge depth of 1 mm, transverse speed as 40 mm/min and tool-spindle rotational speeds of 800 revolutions per minute and 1400 rpm respectively with two numbers of passes in each case. through The microstructural refinement and mechanical properties like tensile and hardness for base steel were studied and compared with friction stir processed steel. The initial grain sizes of the selected boiler steel (25 mm) has been reduced to 7.8 mm and 5.9 mm respectively with increase in rotational speed. The microhardness and tensile strength was evaluated of all the FSPed samples. The microhardness of the FSPed samples was enhanced by factor of 1.72 and 2.38 in comparison to base steel respectively with the increase in rotational speeds; this may be due to phase transformation (austenite to martensite and ferrite) verified by Image processing software ''Image-J" and refinement in grain size as per Hall-Petch equation. The ultimate tensile strength was improved by 7.2% and 15% respectively in comparison to base metal, which may be accredited to enlarge in grain boundaries which hinder the dislocation movement. The characterization was done by optical microscopy and Electron Back Scattered Diffraction (EBSD) analyses with an intend to suggest mechanisms behind grain size refinement and phase transformation.

Proceedings of the ICE - Construction Materials, 2012

The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (... more The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (HyFRC) containing different proportions of steel and polypropylene fibres. An experimental programme was conducted to obtain the fatigue lives of HyFRC specimens at different stress levels in which approximately 113 flexural fatigue tests were conducted. Approximately 60 complimentary static flexural tests were executed for reference purpose. The specimen incorporated different proportions of steel fibres and polypropylene fibres in the ratio of 25–75%, 50–50% and 75–25% by volume. The total fibre content was kept at 1·0% by volume. The test data was used to estimate the coefficients of the fatigue equations representing S–N diagrams. The fatigue test data has also been employed to determine a relationship between fatigue stress level S, fatigue life N and probability of failure Pf, and to generate a family of S–N–Pf curves for HyFRC. The experimental coefficients of the fatigue equation...

Magazine of Concrete Research, 2012

This paper presents the results of an investigation conducted to examine the probability distribu... more This paper presents the results of an investigation conducted to examine the probability distributions and flexural fatigue performance of hybrid fibre-reinforced concrete (HyFRC) containing different proportions of steel and polypropylene fibre. An experimental programme was planned to obtain the fatigue lives of HyFRC, in which approximately 435 beam specimens of size 100 × 100 × 500 mm were tested under four-point flexural loading. Approximately 225 static flexural strength tests were also conducted to facilitate fatigue testing. The specimens incorporated different proportions of steel and polypropylene fibres in the ratio of 25:75%, 50:50% and 75:25% by volume at each fibre volume fraction of 0·5%, 1·0% and 1·5%. The fatigue test data were used to establish probability distributions of HyFRC at different stress levels. The gradual replacement of steel fibres by polypropylene fibres in the HyFRC mix was found to significantly reduce the variability in the distribution of fatigue...

Results of an investigation conducted to evaluate the strength and flexure toughness of Hybrid Fi... more Results of an investigation conducted to evaluate the strength and flexure toughness of Hybrid Fibre Reinforced Concrete (HyFRC) containing different combinations of steel and polypropylene fibres are presented. An experimental programme was planned in which beam specimens of size 100 x 100 x 500 mm were tested under four point static flexural loading to obtain the flexural strength of HyFRC. In addition, cube specimens of size 150 x 150 x 150 mm were also tested to obtain its compressive strength. The specimens incorporated steel and polypropylene fibres in the mix proportions of 100-0%, 75-25%, 50-50%, 25-75% and 0-100% by volume at a total volume fraction of 1.0%. The flexural toughness parameters were obtained using procedure laid down in ASTM C-1018 C, JCI Method, ASTM 1609/C 1609 M and Post Crack Strength (PCS) Method. The results indicate that concrete containing a fibre combination of 75% steel fibres + 25% polypropylene fibres can be adjudged as the most appropriate combination to be employed in HyFRC for compressive strength, flexural strength and flexural toughness.

Proceedings of the Institution of Civil Engineers Construction Materials, 2012

The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (... more The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (HyFRC) containing different proportions of steel and polypropylene fibres. An experimental programme was conducted to obtain the fatigue lives of HyFRC specimens at different stress levels in which approximately 113 flexural fatigue tests were conducted. Approximately 60 complimentary static flexural tests were executed for reference purpose. The specimen incorporated different proportions of steel fibres and polypropylene fibres in the ratio of 25–75%, 50–50% and 75–25% by volume. The total fibre content was kept at 1·0% by volume. The test data was used to estimate the coefficients of the fatigue equations representing S–N diagrams. The fatigue test data has also been employed to determine a relationship between fatigue stress level S, fatigue life N and probability of failure Pf, and to generate a family of S–N–Pf curves for HyFRC. The experimental coefficients of the fatigue equation were also obtained fro...

Magazine of Concrete Research, 2012

ABSTRACT

Materials Today: Proceedings, 2019

The main objective of the current investigation is to achieve strengthening of SA210 Grade A1 boi... more The main objective of the current investigation is to achieve strengthening of SA210 Grade A1 boiler steel using friction stir processed (FSPed) using pinless WC tool with plunge depth of 1 mm, transverse speed as 40 mm/min and tool-spindle rotational speeds of 800 revolutions per minute and 1400 rpm respectively with two numbers of passes in each case. through The microstructural refinement and mechanical properties like tensile and hardness for base steel were studied and compared with friction stir processed steel. The initial grain sizes of the selected boiler steel (25 mm) has been reduced to 7.8 mm and 5.9 mm respectively with increase in rotational speed. The microhardness and tensile strength was evaluated of all the FSPed samples. The microhardness of the FSPed samples was enhanced by factor of 1.72 and 2.38 in comparison to base steel respectively with the increase in rotational speeds; this may be due to phase transformation (austenite to martensite and ferrite) verified by Image processing software ''Image-J" and refinement in grain size as per Hall-Petch equation. The ultimate tensile strength was improved by 7.2% and 15% respectively in comparison to base metal, which may be accredited to enlarge in grain boundaries which hinder the dislocation movement. The characterization was done by optical microscopy and Electron Back Scattered Diffraction (EBSD) analyses with an intend to suggest mechanisms behind grain size refinement and phase transformation.

Proceedings of the ICE - Construction Materials, 2012

The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (... more The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (HyFRC) containing different proportions of steel and polypropylene fibres. An experimental programme was conducted to obtain the fatigue lives of HyFRC specimens at different stress levels in which approximately 113 flexural fatigue tests were conducted. Approximately 60 complimentary static flexural tests were executed for reference purpose. The specimen incorporated different proportions of steel fibres and polypropylene fibres in the ratio of 25–75%, 50–50% and 75–25% by volume. The total fibre content was kept at 1·0% by volume. The test data was used to estimate the coefficients of the fatigue equations representing S–N diagrams. The fatigue test data has also been employed to determine a relationship between fatigue stress level S, fatigue life N and probability of failure Pf, and to generate a family of S–N–Pf curves for HyFRC. The experimental coefficients of the fatigue equation...

Magazine of Concrete Research, 2012

This paper presents the results of an investigation conducted to examine the probability distribu... more This paper presents the results of an investigation conducted to examine the probability distributions and flexural fatigue performance of hybrid fibre-reinforced concrete (HyFRC) containing different proportions of steel and polypropylene fibre. An experimental programme was planned to obtain the fatigue lives of HyFRC, in which approximately 435 beam specimens of size 100 × 100 × 500 mm were tested under four-point flexural loading. Approximately 225 static flexural strength tests were also conducted to facilitate fatigue testing. The specimens incorporated different proportions of steel and polypropylene fibres in the ratio of 25:75%, 50:50% and 75:25% by volume at each fibre volume fraction of 0·5%, 1·0% and 1·5%. The fatigue test data were used to establish probability distributions of HyFRC at different stress levels. The gradual replacement of steel fibres by polypropylene fibres in the HyFRC mix was found to significantly reduce the variability in the distribution of fatigue...

Results of an investigation conducted to evaluate the strength and flexure toughness of Hybrid Fi... more Results of an investigation conducted to evaluate the strength and flexure toughness of Hybrid Fibre Reinforced Concrete (HyFRC) containing different combinations of steel and polypropylene fibres are presented. An experimental programme was planned in which beam specimens of size 100 x 100 x 500 mm were tested under four point static flexural loading to obtain the flexural strength of HyFRC. In addition, cube specimens of size 150 x 150 x 150 mm were also tested to obtain its compressive strength. The specimens incorporated steel and polypropylene fibres in the mix proportions of 100-0%, 75-25%, 50-50%, 25-75% and 0-100% by volume at a total volume fraction of 1.0%. The flexural toughness parameters were obtained using procedure laid down in ASTM C-1018 C, JCI Method, ASTM 1609/C 1609 M and Post Crack Strength (PCS) Method. The results indicate that concrete containing a fibre combination of 75% steel fibres + 25% polypropylene fibres can be adjudged as the most appropriate combination to be employed in HyFRC for compressive strength, flexural strength and flexural toughness.

Proceedings of the Institution of Civil Engineers Construction Materials, 2012

The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (... more The paper presents a study on the flexural fatigue strength of hybrid fibre-reinforced concrete (HyFRC) containing different proportions of steel and polypropylene fibres. An experimental programme was conducted to obtain the fatigue lives of HyFRC specimens at different stress levels in which approximately 113 flexural fatigue tests were conducted. Approximately 60 complimentary static flexural tests were executed for reference purpose. The specimen incorporated different proportions of steel fibres and polypropylene fibres in the ratio of 25–75%, 50–50% and 75–25% by volume. The total fibre content was kept at 1·0% by volume. The test data was used to estimate the coefficients of the fatigue equations representing S–N diagrams. The fatigue test data has also been employed to determine a relationship between fatigue stress level S, fatigue life N and probability of failure Pf, and to generate a family of S–N–Pf curves for HyFRC. The experimental coefficients of the fatigue equation were also obtained fro...

Magazine of Concrete Research, 2012

ABSTRACT