LG610L汽车大梁钢的拉伸断口及显微结构分析

The Tensile Fracture and Microstructure Analysis of LG610L Automobile Beam Steel

利用拉伸试验机、金相显微镜、扫描电镜和透射电镜等检测工具,对LG610L钢板不同位置的试样进行检测分析,研究结果表明:LG610L钢表面处的组织晶粒比较细小,平均尺寸约为7μm,越靠近中心处晶粒尺寸越大,中心处的晶粒平均直径约为13μm.在横向的1/4处珠光体呈较明显的带状分布,而在表面和中心处带状组织不明显.拉伸断口为韧性断口,其中纤维区为典型的等轴韧窝,放射区多为撕裂韧窝或剪切韧窝,外缘区为涟波花样和无特征区域.析出物呈蚕豆状,其长度方向尺寸范围为15~30 nm,宽度方向尺寸范围为5~12 nm,且呈弥散分布,分布的形状呈“虚线”状.

By means of tensile testing machine,metallographic microscope,scanning electron microscope and transmission electron microscope,the specimens of LG610L steel plate in different positions are tested and analyzed.The results show that the grain size on the surface of LG610L steel is smaller,and the average grain size is about 7μm.The closer to the center,the larger the grain size is,and the average diameter of the grain at the center is about 13μm.The banded distribution of pearlite in the transverse 1/4 is more obvious,but the banded tissue on the surface and the center is not obvious.The tensile fracture is a ductile fracture,in which the fiber region is a typical equiaxed dimple,the radiation zone is a tear dimple or shear dimple,and the outer edge is a ripple pattern and a non-characteristic area.The precipitates are in the shape of broad bean,the length direction size is between 15 nm and 30 nm and the width direction dimension is between 5 nm and 12 nm,and distributes diffusely,the shape of distribution is"dotted line"shape.