不同焊接位置海洋平台用钢焊缝金属低温断裂韧性

Low temperature fracture toughness of welding metal of offshore platform steel in different welding positions

关键词:  横焊  立焊  焊缝金属  低温断裂韧性

Key words:  welded in horizontal position  welded in vertical position  welding joint metal  low temperature fracture toughness

摘要:

海洋平台用钢在横焊立焊位置下,焊缝金属低温断裂韧性存在差异,工程界普遍认为,高热输入的立焊位置试样韧性值低于低热输入的横焊位置试样,但诸多试验均呈现相反的结果.文中选取了两组CO₂焊横焊立焊位置的焊缝金属试样进行了低温断裂韧性试验,得出了CTOD(裂纹尖端张开位移)值,并对焊缝处宏观形貌、断口形貌以及金相组织进行了分析.结果表明,由于柱状晶数量和取向及夹渣的影响,横焊位置试样低温断裂韧性低于立焊位置试样.

Abstract:

The low temperature fracture toughness of welding metal is different for offshore platform steel when welded in horizontal and vertical positions. Several tests indicate that the toughness values of vertical welding position specimens with high heat input were higher than those of horizontal welding position specimens with low heat input, which are the reverse results of general consensus. Two groups of tests welded by FCAW were conducted, one is in horizontal position and the other one is in vertical position. After the CTOD (Crack Tip Opening Displacement) values were obtained, the macrographs, fracture surface morphologyand microstructure were analyzed. The result showed that the toughness values of vertical welding position specimens were higher than those of horizontal welding position specimens because of columnar crystal structure and slag inclusion.