Microstructure Property relation in thermo-mechanical control processed Low Carbon Microalloyed Steel for LPG Cylinder

SANTOSH KUMAR; B Sunita Minz; Saurav Ghosh; N Mondal; Dhirendra Kumar

Abstract

LPG Cylinder manufacturing is a cylindrical forming process which involving strength as well as deep drawing and welding properties. An LPG cylinder is a safety critical components and demands very careful selection of steel quality. LPG cylinder is undertaken in India mainly by using a superior grade Al-killed low-carbon micro alloyed steel with limits of S and P control, under the specification of IS 6240, IS 15914, EN 10120 and JIS G3116. A critical difference of these grades is that the formed cylinders are subjected to normalizing treatment in the range of 880-920oC or stress relieving treatment in the temperature range of 690-710oC.Present work has been carried out to alloy design to achieve higher yield strength, tensile strength and elongation etc. to compensate drop in mechanical properties. Higher strength steel for LPG Cylinder has been made by alloy design technology and combining controlled rolling and controlled cooling through thermo-mechanical control process at Bokaro Steel Plant. This paper describes the practical and cost effective solution for improving the formability and strength of LPG grade steel by evolution of microstructure-property relation.KeyWord: TMCP, HSLA Steel, LPG Cylinder, Tensile test, Microstructure

Abstract

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