Research On Forming Mechanism Of Banded Structure In60Si2Mn Spring Flat Steel And Its Influence On Mechanical Properties

Spring flat steel is one of the key materials which affects not only the service life ofvehicle, but also to ensure the safety in using. It is required higher quality as it is more largelyused in automotive materials. The microstructure should have higher requirements, in order toprolong the service life of the spring flat steel.For the band structure of the scene60Si2Mn spring flat steel, this study put forward anew evaluation method, test it by using Leica metallographic microscope and SEM, analyzethe occurrence of banded structure on the mechanical behavior of products, study theformation mechanism of banded structure, discuss the evolution course of banded structureand summarizes the influence of rolling process parameters on the banded structure.The center banded structure in60Si2Mn spring flat steel is pearlite, it has created theanisotropic in60Si2Mn spring flat steel, and also has a great influence on its mechanicalproperties; in this paper, based on“center pearlite bandwidth ratio”to confirm the severity ofbanded structure, and puts forward a new evaluation method.Analysis of microstructure and composition show that the root cause of the formation ofbanded structure is segregation of alloying elements, especially the influence of C and Mnelement, MnS in steel is also easy to promote the formation of banded structure.Rolling test show that: Using a longer time of heat preservation can improve thesegregation of continuous casting billet, and also reduce the center banded structure inproduct; with the increase of the compression ratio of rolling, pearlite bandwidth will decrease,the degree of banded structure will be relieved; compared with the slow cooling conditions,under the condition of air cooling banded structure is smaller.