大线能量焊接EH36船板钢FCB焊接接头组织与性能

对工业化试制的32 mm厚大线能量船板钢EH36进行热输入为228 k J/cm的FCB法焊接试验,并研究了焊接接头的组织和力学性能。结果表明:焊接热影响区的过热粗晶区原奥氏体晶粒尺寸达到300~500μm,组织主要由少量晶界铁素体和晶内形核铁素体(约60%~80%)组成,是该区焊接时峰值温度达到δ相转变温度以上并停留较长时间造成的,并给出δ相转变温度及奥氏体晶粒尺寸与峰值温度之间的关系;粗晶区由15~30μm的多边形铁素体与3~10μm的针状铁素体(10%~20%)构成;细晶区包含10~20μm的多边形铁素体和小于等于10μm的珠光体;临界区表现为混晶组织。焊接接头热影响区的冲击功A_(kv)≥100 J(-20℃),拉伸试样断裂于母材,接头性能满足要求。

Microstructure and properties of FCB weld joint of shipbuilding steel EH36 for high heat input welding

FCB welding with an heat input of 228 kJ/cm was applied to butt weld newly developed 32 mm thick shipbuilding steel plate EH36,and the microstructure and mechanical properties of the weld joint were examined.Super coarse grain heat affected zone of the weld joint mainly consists of intra-granular nucleated ferrite and small amount of grain boundary ferrite.The size of prior austenite grain is 300～ 500 μm,which is caused by longer soaking at high temperatures during thermal cycle.In this paper,δ phase-transition temperature and relationships between austenite grain size and peak temperatures are given.Coarse grain heat affected zone mainly consists of 15～30 μm acicular ferrite and 3～10 μm acicular ferrite.A microstructure consisting of 10～20 μm acicular ferrite and ≤ 10 μm pearlite is observed in fine grain heat affected zone.Inter-critical heat affected zone consists of mixed grains.The heat affected zone exhibits an absorbed energy larger than 100 J at-20 ℃ during CVN impact test.The weld joint failed in the base metal during transverse tensile testing,and other properties meet the requirement.