冶炼工艺对大热输入海洋工程用钢E36N组织性能的影响研究

Study on Effect of Smelting Process on Microstructure and Properties of High Heat Input Steel E36N for Marine Engineering

采用新工艺及传统工艺冶炼的两种海洋工程用正火态钢E36N进行热输入为200 kJ/cm的焊接热影响区热模拟实验,在-20℃的条件下检测焊接热模拟试样的冲击功值,在光学显微镜下观察其金相组织,在扫描电镜下观察冲击断口形貌以及夹杂物情况,研究在相同的大热输入条件下,两种冶炼工艺得到的E36N钢的熔合线附近的粗晶热影响区组织及其低温韧性。结果表明,传统工艺冶炼得到的E36N钢的焊接热模拟组织主要为贝氏体+少量铁素体,热影响区(HAZ)的低温韧性较差。新工艺冶炼得到的E36N钢的焊接热模拟组织为少量晶界铁素体、少量多边形铁素体及大量针状铁素体,HAZ具有良好的低温韧性。

Two kinds of normalizing state E36 N steels smelted by a new process and traditional process for marine engineering was used to simulate the welding HAZ under heat input of 200 kJ/cm.The impact energy values of the welding heat simulation specimens were tested at-20℃,the microstructure was observed by optical microscope,and the impact fracture morphology and inclusions were observed by scanning electron microscope.The microstructure of the coarse grain heat affected zone near the fusion line of the E36 N steel obtained by the two smelting processes and its low temperature toughness were studied under the same high heat input.The results show that the thermal simulation microstructure of E36 N steel smelted by the traditional process is mainly bainite+a small amount of ferrite,and the low temperature toughness of heat affected zone(HAZ)is poor.The thermal simulation microstructure of the E36 N steel smelted by the new process is a small amount of grain boundary ferrite,a small amount of polygonal ferrite and a large number of acicular ferrite.The HAZ has good low temperature toughness.