高强钢DP780压扁开裂原因分析
Analysis of the Causes of Flattening and Cracking of High-strength Steel DP780
李增丰 1刘宇1
作者信息
- 1. 河钢股份有限公司唐山分公司,河北 唐山 063000
- 折叠
摘要
随着汽车轻量化的发展,先进高强钢材料的应用成为减轻车身重量和提高汽车防撞性能的重要途径.某厂家采用连退DP780高强钢通过辊压工艺加工圆管生产座椅骨架,但检验压扁工艺性能时,试样出现开裂现象.对压扁开裂试样和合格试样进行理化检验分析,扫描电镜和金相分析未发现明显夹杂物,压扁开裂试样金相组织较合格试样有粗大的块状马氏体,合格件马氏体细小,弥散分布在铁素体基体中.进行折弯性能和扩孔性能实验分析,压扁开裂样板180°折弯后,出现了开裂现象,其扩孔率为20.3％,低于合格样板的24.7％.综合分析,成分体系的差异造成开裂产品组织晶粒较为粗大,变形过程晶粒间协调性差,以及低的折弯性能和扩孔性能,是此次圆管压扁开裂的主要原因.
Abstract
With the development of automotive lightweighting,the application of advanced high-strength steel materials has become an important way to reduce vehicle weight and improve automotive collision resistance performance.A certain manufacturer used continuous annealing DP780 high-strength steel to process round tubes for seat frames through rolling technology.However,during the inspection of the flattening process performance,cracks appeared in the sample.Physical and chemical inspection and analysis were conducted on the flattened and qualified samples,and no obvious inclusions were found in the scanning electron microscope and metallographic analysis.The metallographic structure of the flattened and cracked samples was larger than that of the qualified samples,and the martensite in the qualified samples was fine and dispersed in the ferrite matrix.After conducting experimental analysis on bending performance and hole expansion performance,it was found that cracking occurred on the flattened cracked sample after being bent 180 °.The hole expansion rate was 20.3％,which was lower than the qualified sample's 24.7％.Based on comprehensive analysis,the differences in composition systems caused the cracking of the product,resulting in coarser grain size,poor coordination between grains during deformation,as well as low bending and expansion performance,which were the main reasons for the cracking of the round tube during flattening.
关键词
780DP/压扁开裂/合金元素/组织/扩孔率Key words
780DP/flattening and cracking/alloy elements/organization/expansion rate引用本文复制引用
出版年
2024
NETL
NSTL
万方数据