The INFLUENCE OF COMPOSITION AND PROCESSING PARAMETERS ON THE DROP WEIGHT TEAR TEST (DWTT) PROPERTY OF HIGH GRADE LINEPIPE STEEL

摘要

In order to study the influencing factor and the method of improving Drop Weight Tear Test (DWTT) property of high grade linepipe steel, DWTT was conducted on high grade linepipe steels with two different chemical compositions and different rolling parameters. The results show that the application of low carbon Mn-Mo-Nb composition, with the suitable Thermomechanical Control Process (TMCP) parameters can help to get the good DWTT property as well as the high strength. The proper TMCP parameters, such as decreasing the finishing mill entering temperature, can promote the refinement of prior austenite grain size. In addition, the appropriate control of cooling rate and finish cooling temperature to get the dispersed distribution of M/A islands is also important to get excellent DWTT property.