الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Ferrite grain-refinement is a promising approach to improve both the strength
and the toughness of steels simultaneously. Among recent ferrite refinement techniques,
dynamic strain induced transformation (DSIT) is applied. In this work, a framework
consisting of 24 plant scale trials (160 tons each) was performed in the compact strip
production (CSP) plant at EZDK company. Micro-alloying with Nb (0.002, 0.022, 0.032
and 0.042 wt%) along with designing the hot rolling parameters (strain, hot deformation
temperature at each of six rolling stands and the coiling temperature) were used to
produce the required microstructure and properties. The effect of change both Nb content
and rolling parameters on grain refining, mechanical properties and formability of hot
rolled low carbon steel were linked and studied. Stress induced grain refinement has been
successfully achieved, aided by Nb, resulting in an average grain size of 3.3 μm with
enhanced strength, ~ 615 MPa, yet with adequate ductility (22%) and formability.