EH40船用高强钢双丝气电立焊接头组织与性能

Microstructure and Mechanical Properties of Welded Joints of EH40 Ship Steel Plate by Two-electrode Electrogas Welding

对板厚68 mm的EH40船用高强钢进行了热输入分别为382、440和450 kJ/cm的双丝气电立焊试验,借助焊接接头的拉伸试验、冲击试验、硬度测试及显微组织分析等方法,研究了热输入对EH40钢大厚板双丝气电立焊接头组织和性能的影响。结果表明,大热输入焊接主要通过控制针状铁素体形核长大、改变晶界铁素体形貌及奥氏体晶粒大小来影响EH40钢焊接接头的组织和性能。随着热输入增加,接头强度降低,热影响区软化倾向增大。热输入过大或过小都对焊缝金属韧性不利,纵观焊接接头整体力学性能的变化,在坡口角度20°、间隙8 mm条件下,其最佳的热输入为400-440 kJ/cm。

The weldability of EH40 ship steel plate with 68ram thickness by two-electrode electrogas welding with highheat-input 382 ld/cm,440 kJ/cm and 450 kJ/cm respectively was studied by tensile test, impact test, hardness test andmicrostructure. The results show that the microstructure and mechanical properties of EH40 welded joint depends on thenucleation and growth of acicular ferrite, morphology of grain boundary ferrite, and austenite grain size by the influence ofdifferent heat-input. With the increase of heat-input, the strength of welding joint decreases and the softening of HAZ tends tobe serious. Whether the heat-input is too large or too low is harmful to welded metal toughness. Throughout the mechanicalproperties changes of the whole welded joint, there is an optimum heat-input, i.e. 400-440k3/cm under the conditions thatgroove angle is 20° and the slope gap is 8 mm.