If Steel Cold Rolling Process Parameters And The Deep Red-performance Relationship

Now the development of automobile industry need the Plastic strain ratio r-value of IF steel reach about 3.0. In order to achieve this aim, the technology of single cold rolling and double cold rolling was designed, and by the measurement of Plastic strain ratio r-value, tensile strain hardening exponents n-value and the analysis of microstructure and microtexture, the drawability of a Ti-IF steel which was lubriciously hot rolled in ferrite region and produced in Baoshan Iron & Steel Co. was investigated in this paper. The main work and results are as following:1. The formula between r-value and cold rolling parameters for different technology was got by means of regression.2. The relationship between cold rolling technology parameters and drawability was investigated. The key factor influences the drawability of IF steel dealt with simple cold rolling technology is cold rolled reduction. The r-value reaches maximum when the cold rolled reduction is about 75% and this maximum is about 1.7 on condition that the IF steel cold rolled without lubrication. The annealing time has little influence on drawability if the conditions for recrystallization were met. For double cold rolling technology, the main factors that influence the drawability are the total cold rolled reduction and the distribution of the total reduction in two cold rolling courses. In the range of the experiment, annealing technology has some influence on drawability when the total reduction is below 75%, but the key factor influences drawability is the distribution of the total reduction when it is above 81.25%. The influence of annealing technology can be ignored in this condition.3. Double cold rolling technology can improve the drawability of IF steel markedly when compared with single cold rolling technology. The r-value can reach about 3.0 and maximum can be 3.3 on condition that the distribution of the total reduction is correct.4. The formation mechanism of {111}//ND recrystallization texture was analyzed. The author got the following ideas in reference to some relevant researches: In-grain shear bands fragmented ND fibre grains, this general fragmentation leads to the nucleation of ND fibre grains at sites situated both within the grain interior and at the grain boundary. As a result, the amount of ND fibre grains increased and {111}//ND recrystallization texture is intensified after annealing.5. The change and the formation mechanism of texture in the courses of the second cold rolling and the second annealing were analyzed and discussed.6. Analyzed the change of texture in the direction of sample's thickness which influenced by friction and got a conclusion that cold rolled with favorable lubrication can improve the drawability of IF steel.