Steel Authority of India

About: Steel Authority of India is a based out in . It is known for research contribution in the topics: Microstructure & Ultimate tensile strength. The organization has 797 authors who have published 661 publications receiving 9958 citations. The organization is also known as: SAIL.

Development and characterization of steel containing very fine ferrite grains

Abstract: Ferrite grain sizes of the order of 1 to 2 µm were obtained by optimizing the strain, strain rate, the stage of cooling, as well as the cooling rate during hot rolling of 0.15C-0.92Mn-0.01Si-0.036S-0.04P-0.013Nb steel. It was found that in single-pass rolling of a 10 mm plate to a thickness of 3.5 mm with an entry temperature of 800 °C, and early-stage water cooling, very fine grains of ferrite (1–2 µm) were formed at the surface and in subsurface regions. It was also found that the threshold level of reduction during rolling, which is required for the refinement of ferrite grains, is >50%. The 3.5 mm thermomechanically processed plate was found to possess very attractive mechanical properties in terms of the yield strength (485 MPa), the ultimate tensile strength (UTS) (763 MPa), and particularly the yield strength to ultimate tensile strength (YS/UTS) ratio (0.63). This combination of properties can be explained on the basis of the composite microstructure consisting of ferrite and bainite that was obtained as a result of the thermomechanical processing.

Effect of simultaneous addition of CaO–Al2O3 flux and CaSi on the modification of inclusions in aluminium-killed steel

Abstract: This paper investigates the effect of CaO-Al 2 O 3 flux, used in conjunction with CaSi, on the formation of inclusions in aluminium-killed steel. 50 kg scale experiments were carried out in an air induction furnace. The amounts of CaSi (1.25-2.5 kg/t) and fluxes (CaO:Al 2 O 3 from 40:60 to 60:40) were varied in different experimental heats. The volume fraction and size of inclusion were determined through quantitative metallography. The change in the composition of inclusions was qualitatively studied through elemental x-ray analysis by EPMA. The size of inclusions in general was found to be larger in the case of the simultaneous addition of CaSi with flux, compared to that obtained through CaSi alone. Larger inclusions lead to easier flotation resulting in lesser volume fraction. The inclusion content was lowest with flux containing 40% CaO and 60% Al 2 O 3 . Better globularisation of alumina inclusion was observed in the case of the simultaneous addition of flux with CaSi, compared to situations where CaSi alone is added. The present investigation has therefore identified the specific amount and composition of flux necessary for restricting the inclusion content as well as improving its globularisation.

Wing profile sail

Abstract: Wing profile sail for sailboats and sailboards, formed by a flexible sheet (1) having a leading edge (2) configured to be coupled to a mast (4) and comprising inflatable bladder means (6, 7) extending along the direction of the leading edge (2), rearward thereto, to provide a wind profile to the sail. The inflatable bladder means (6, 7) comprise multiple pockets (6a-6d; 7a-7d) fixed to the opposite surfaces (1a, 1b) of the flexible sheet (1) and localized behind its leading edge (2).

Influence of different heat treatment parameters on microstructure and mechanical properties of C–Mn strapping quality steels

Abstract: Strap steel produced at Bokaro Steel Plant is a plain C–Mn (nominal chemistry C: 0.35%, Mn: 1.35% and Si: 0.25%) cold rolled steel that is austenitised at 930 °C and austempered in a lead bath at 450 °C. The microstructure consists of ferrite, pearlite and bainite also to achieve ultimate tensile strength (UTS) 900 MPa min and elongation 8% min on 150 mm gauge length. In order to achieve such a microstructure consistently, influence of chemistry and different heat treatment parameters on strapping quality steels have been studied. It has been found in the laboratory that increase in Mn (from 1.35 to 1.55%) and Si (from 0.25 to 0.45%) in a 0.32% C strap steel results in 100% bainite in the microstructure after austenitisation and subsequent air cooling. The austempering of the modified strap steel (0.4% C, 1.65% Mn and 0.5% Si) at Bokaro Steel Plant results in excessively high UTS (1040–1100 MPa) without affecting the elongation value (8–10%, 150 mm GL). The microstructure of the austempered straps of modified chemistry consists of cent percent bainite. The austenitisation and subsequent air cooling without austempering of the modified strap steel result in a microstructure consisting of ferrite, pearlite and bainite. The UTS (867–875 MPa) achieved marginally falls short of the specified values (900 MPa min) while % elongation values (8–10%, 150 mm GL) conform to the IRS: P-41 specification.