X70级管线钢不同缺口形式的落锤撕裂试验研究

Study on Different Notch Types of Drop-Weight Tear Test on Grade X70 Pipeline Steel

在不同试验温度条件下,对各种缺口形式的X70级管线钢DWTT试样进行了落锤撕裂试验,并对试验中的有关数据进行了分析。试验和分析结果表明:X70级管线钢在室温下具有很高的断裂韧性,破坏后断口有明显的分层现象;X70级管线钢韧脆转变温度在-20℃^-30℃之间;在一定温度范围内,压制缺口试样异常断口出现的概率较大;异常断口的出现是由形变硬化、温度等因素造成的。针对高钢级管线钢出现的异常断裂现象,有待于改进断口的评价标准,以使其更客观地反映材料的止裂能力。

To conduct drop weight tear test to DWTT specimen for each kind of notch type of grade X70 pipeline steel under different test temperature conditions and analyzes the related datum during test.The test and analysis result shows that grade X70 pipeline steel has high fracture toughness under room temperature and fracture has obviously lamination phenomenon after tear,toughness to brittle transfer temperature of grade X70 pipeline steel is between -20 ℃^-30 ℃,occurred of irregular fracture to pressed notch specimen is greater under certain temperature range.Occurrence of irregular fracture is caused by transformation harden and temperature,etc..Irregular fracture break occurred on high grade pipeline steel is needed to improve appraisal criteria of fracture to make it more realistically reflect anti-tearing capacity of materials.