Research Of300Austenitic Stainless Steel Flatness And Properties Control

Nowadays the domestic enterprises face the problem of the stainless strip shape andperformance are difficult to control in cold rolling production.It always needs to bedeveloped different process parameters in order to meet special use of stainless strip inactual production process. So many advanced technology and equipments are adopted byenterprises to realize the on-line control to the current difficulties.This paper is based on a cold rolling stainless steel enterprise as reserch background,considering from the cold rolling process and annealing process of0.262mm301B extrahard spring stainless strip and0.25mm304etching stainless strip. Besides, universialtensile machine and slerometer are applied to test mechanical properties of the strip,analyse the strengthen theory of301B in annealing process as well as internal relationbetween grain boundary feature and surface hardness of304through the advancedtechnology such as microstructural observation, XRD, EBSD. Based on the actual coldrolling process data, Software of ANSYS/LS-DYNA was employed to simulated coldrolling process of twelve high rolling mill in order to grasp the law of intermediate rolltraverse quantity. The main researches are as follows:Combined with practical production，Aimed at improving elasticity and fatigue life ofthe301B extra hard stainless steel as spring，this paper summarized a suitable cold rollingand annealing process by making hardness test and tensile experiment on301B austeniticstainless steel with a thickness of0.262mm. As well as analyzing the reason why themechanical property changed by using X-ray diffractometer. The result shows that thehardness and strength of the strip obviously improved after annealing process. Besides,applying the cold rolling process of increasing the deformation rate and reducing therolling oil and speed can also be made the mechanical property and the corrosion resistingproperty improved obviously after annealing process under the temperature of450℃andthe velocity of7.8m/min. To ensure304austenitic stainless steel still keep original strip shape with goodflatness after etching process, this paper based on the practical production, taking304austenitic stainless steel with a thickness of0.25mm for example, and having the annealingprocess outside the sensitive temperature at400℃and900℃, then measuring its surfacehardness which are controlled through the cold reduction rate. Effects of differentannealing temperature on the microstructures and surface hardness of304stainless steelhave been investigated. The result show that304austenitic stainless steel with27%reduction rate after annealing process at900℃can not only keep good strip flatness butalso obtain the required hardness at the same time.EBSD technology is adopted to research the grain boundary characteristic of304austenitic stainless steel under different tension in the process of annealing at700℃.Theresult shows that the sub-grain and the surface hardness increase with adding tension in theprocess of annealing. The inner structure of304stainless strip exists a large number ofannealing twin, and the orientation relation with original body is <111>/60°，which is the∑3lattice relationship.Software of ANSYS/LS-DYNA was employed to simulated cold rolling process oftwelve high rolling mill in order to grasp the law of intermediate roll traverse quantity withthe change of the strip width. Calculated the loaded gap of the work roll and the straindistribution curve of the304stainless steel when intermediate roll traverse quantity range-30mm from-50mm.The results show that adjust intermediate roll traverse quantitydynamically to change the value of L, account for55to60percent of the strip width,strip shape with good flatness can be obtained.The simulation value is consistant with theactual value,which show the accuracy and reliability of the model.The strip shape、mechanical property and the corrosion resisting property control of301B and304stainless steel get obvious effect during the experiment. The research resultof this paper offered a new method and optimized the cold rolling and annealing process tothe actual production,and create a great production benefit. The content of this paper has abig meaning and contribution to the development society.