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采用埋弧焊焊接X70级管线钢。采用OLYCIA m3软件对热影响区的晶粒度进行评级,采用OLYMPUS-PMG3光学显微镜对热影响区进行显微组织观察。结果表明,经过焊接热作用后,母材中原始的针状铁素体组织和少量的珠光体组织转变为粗大的粒状贝氏体组织。X70级管线钢为细晶粒钢,受焊接高温热作用后,其晶粒具有长大倾向。焊接过程中,热输入越高,晶粒长大倾向越严重。焊接热输入为30.6 kJ/cm时,其过热区粒状贝氏体组织的晶粒尺寸为热输入19.04 kJ/cm条件下粒状贝氏体晶粒尺寸的1.2倍。
Submerged arc welding X70 grade pipeline steel. The grain size of heat-affected zone was rated by OLYCIA m3 software. The microstructure of heat-affected zone was observed by OLYMPUS-PMG3 optical microscope. The results show that the primary acicular ferrite and a small amount of pearlite transformed into coarse granular bainite after the heat of welding. X70-class pipeline steel for the fine grain steel, by welding high temperature heat, the grain growth tendency. Welding process, the higher the heat input, the more serious the tendency of grain growth. When the welding heat input is 30.6 kJ / cm, the grain size of the granular bainite in the overheated zone is 1.2 times the grain size of the granular bainite under the heat input of 19.04 kJ / cm.