37 International Conference on Automotive Steel – Outlook & Perspective (AutoSOP 2015), Bokaro Steel City, Jharkhand, India Process Optimization for Microstructure evolution of Annealed Cold Rolled Steel B Sunita Minz 1 , Santosh Kumar 2 & Roselin Dodrae 1 1 SAIL, Bokaro Steel Plant, Bokaro Steel City, Jharkhand-827011, India 2 SAIL, RDCIS, Bokaro Steel City, Jharkhand-827011, India Email: sunitajane@gmail.com Bokaro Steel Plant is in progress on machinery rehabilitation in different mill sections and commissioning of new 1.2 MT cold rolling mill (CRM) will be used to produce high-quality steel grades for applications in the automotive industry. The new rolling mill consists of a coupled Pickling Line-Tandem Cold Mill (PLTCM), an Electrolytic Cleaning Line (ECL), Bell Annealing Furnace (BAF) and a Hot Dip Galvanizing Line (HDGL). The purpose of this study is to assess the impact of cold rolling reduction of 80-92% and hydrogen annealing in BAF with high efficiency of heat transfer on mechanical properties of low carbon grade steel and then aim to characterize the microstructural evolution of the material for annealing process optimisation. Mechanical properties such as yield stress, ultimate tensile stress, elongation, hardness and r-bar have been evaluated for different grades of low carbon steel processed under different conditions. These results are then verified by microstructural characterization, using techniques such as optical microscopy, electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM) and transmission electron microscopy (TEM). Heat treatment with controlled rate of cooling for arresting grain growth and surface modification are the key technologies to enhance the effective use of materials and to achieve the desired properties of the material used in the automotive industries. The tested parameters of annealing, mainly temperature and time together with other factors like total cold reduction have the decisive influence on the microstructure and hence mechanical properties after annealing. Strength and drawability properties of the material decrease with increase in annealing temperature whereas, on the contrary, plastic properties increase. Keywords: Microstructural Evolution, Annealing Process Optimization, Cold Rolled Steel 1.0 INTRODUCTION Lighter vehicles with enhanced safety and energy consumption are the needs of the automobile industry and the use of high strength steel can help comply with the statutory requirements. Focusing on the increasing demands of this sector, the construction of the new state-of-the-art cold rolling mill at Bokaro Steel Plant and the technology employed will enable production of high quality cold-rolled products for applications in the automotive industry. EDD grade steel has continued to maintain its position as a major input material for manufacturing various components of intricate shape both for light and commercial vehicles. Today, automotive manufacturers demand superior quality steel with higher level