高性能WNQ690钢气体保护焊试验研究

Experimental research on gas metal arc welding of WNQ690 steel

以WNQ690钢为研究对象，采用气保护焊接工艺，焊接线能量控制在15kJ／cm，WER70NH匹配WNQ690钢进行焊接，研究WNQ690钢焊接性能及焊接组织结构。接头抗拉强度为750MPa，冷弯性能优良，焊缝-40℃平均冲击功为137J，熔合线及热影响区冲击功均达到较高水平，焊接接头的HV10硬度在234-300之间，说明WNQ690钢淬硬倾向较小。WNQ690钢材的组织为回火贝氏体，焊接接头过热区组织为贝氏体，焊缝中含有较多的针状铁素体和少量的先共析铁素体，焊接热影响区的细小贝氏体组织使焊接热影响区具有较高的冲击韧性。

The weldabilities and structures of welding joint of WNQ690 steel were studied by mean of GMAW test with an energy control of 15 kJ/cm and using WERTONH as the matching wire. The tensile strength of joints reached 750 MPa, the result of cold-bending test was satisfactory, the impact energy of joints in -40℃ was 137 J, fusion line and the heat affected zone belonged to a higher level, the hardness of welded joints HV10 was in a range between 234 to 300. All the above results showed that the welding joint of WNQ690 had superior mechanical properties and low hardness ability. The microstructure of WNQ690 was tempered bainite, the heat affected zone of welded joints was made up of bainite, more acicular ferrite and a few proeutectoid ferrite were observed in the joints. Higher impact toughness of the heat affected zone can be attributed to a high fraction of acicular ferrite in welded materials.