Q235B 热轧H型钢拉伸试验分层断口的显微分析

Q2 35B热轧H型钢拉伸试验后出现分层断口。用扫描电镜进行了显微观察 ,发现分层现象与试样中超长的带状组织密切相关。用能谱仪对断口分层处和超长铁素体带上的夹杂物进行了成分分析 ,证实都是硫化物。试样拉伸时在铁素体带上密集分布的硫化物处产生大量微裂纹 ,同时超长铁素体带的变形又受到阻碍 ,导致该处在试样拉断之前裂纹已经贯通 ,最终在断口上形成分层。因此 ,拉伸试验断口出现分层的原因是试样中存在密集分布的硫化物和超长的带状组织。

Microstructure Analysis for Layered Fracture of Q235B Hot-Rolled H Section Steel after Tension Test

The sample of Q235B hot-rolled H section steel had a layered fracture after tension test.The observation with scanning electron microscope showed that the layered fracture was related to very long banded structure in the sample. The sulphide inclusions located at the layered zone on the fracture and on the very long ferrite band resulted in very fine crack during tension test. That the deformation of ferrite band was hinder resulted in crack perforation before the sample ruptured,and finally layered fracture was formed. The layered tension fracture was form by crowded sulfides and very long banded structure in the sample.