Q370R???????????????????

 对存在沿轧制方向分布的表面呈沟状、网状的裂纹和发纹的Q370R板材样品进行了观察分析。通过化学分析、力学性能检测、显微组织观察、扫描电镜分析研究裂纹的形成原因。结果表明：样品化学成分、力学性能符合GB/713-2008标准，基体组织正常；通过能谱分析未检测到裂纹附近存在低熔点有害元素；存在沟状、网状裂纹及发纹的样品均发现了大量的皮下气泡。Q370板的表面裂纹和发纹主要是由铸坯表面气泡和皮下气泡所致。

Cracking Analysis of Steel Plate Q370R

The surface crack of steel plate Q370R was observed and analyzed by means of mechanical property,chemical composition,microstructure and scanning electron microscope to find out the causes for the cracks.The results show that the chemical composition and mechanical properties meet the National Standard GB/713-2008.The microstructure observation shows that the microstructure of the sample is normal.The energy spectrum analysis shows that there are no low melting temperature elements near the crack.The optical microscope and SEM observation reveal that a large number of subsurface bubbles in the samples.The results show that the cracks are mainly caused by the surface bubble and subsurface bubble.