埋弧焊焊道裂纹的原因：埋弧焊直缝钢管温度要求及产生夹渣的原因
埋弧焊焊道裂纹的原因：埋弧焊直缝钢管温度要求及产生夹渣的原因The production characteristics of submerged arc welded straight seam steel pipe can eliminate the cause of weld slag inclusion due to unclean interlayer during multi-layer welding.In view of the fact that there are many inclusions in the raw materials and the slag inclusion in the weld after taking measures such as inspection of the base metal before welding replacement of welding wire and flux
埋弧焊直缝钢管采用的焊接工艺为埋弧焊技术，采用填充物焊接，颗粒保护焊剂埋弧。生产的口径可以达到1500mm LSAW是埋弧焊直缝钢管的英文简称，埋弧焊直缝钢管的生产工艺有JCOE成型技术、卷制成型埋弧焊技术。当口径较大时可能用两块钢板进行卷制，这样会形成双焊缝的现象。The welding process used for submerged arc welded straight seam steel pipe is submerged arc welding technology which adopts filler welding and particle protection flux submerged arc. The diameter of production can reach 1500mm. LSAW is the English abbreviation of submerged arc welded straight seam steel pipe. The production process of submerged arc welded straight seam steel pipe includes JCOE forming technology and coil forming submerged arc welding technology. When the diameter is large two steel plates may be used for rolling which will form the phenomenon of double welds.
Requirements for welding temperature of straight seam steel pipe:
材质为低碳钢，焊接温度控制在1250~1460℃，可满足3~5mm管壁厚的焊透要求，焊接温度主要通过调节高频涡流热功率和焊接速度来控制。The material is low carbon steel and the welding temperature is controlled at 1250~1460℃ which can meet the penetration requirements of 3~5mm tube wall thickness. The welding temperature is mainly controlled by adjusting the high-frequency eddy current thermal power and welding speed.
当输入热量不足时，受热焊缝边缘达不到焊接温度，金属组织保持固态，导致未熔合或未焊透。当输入热量过大时，受热焊缝边缘超过焊接温度，产生过烧或熔滴，使焊缝形成熔洞。When the input heat is insufficient the edge of the heated weld cannot reach the welding temperature and the metal structure remains solid resulting in incomplete fusion or incomplete penetration. When the input heat is too large the edge of the heated weld exceeds the welding temperature resulting in overburning or molten droplets causing the weld to form a hole.
The production characteristics of submerged arc welded straight seam steel pipe can eliminate the cause of weld slag inclusion due to unclean interlayer during multi-layer welding.
针对原材料中夹杂物较多而使焊缝产生夹渣，采取焊前检验母材、换新焊丝和焊剂等措施后，焊缝熔合线夹渣产生的比例仅略有减少，说明原材料中的夹杂物不是导致夹渣产生的主要原因。In view of the fact that there are many inclusions in the raw materials and the slag inclusion in the weld after taking measures such as inspection of the base metal before welding replacement of welding wire and flux etc. the proportion of slag inclusion in the fusion line of the weld is only slightly reduced indicating that inclusions in the raw materials. It is not the main cause of slag inclusions.
Therefore the main reason for the fusion line slag inclusion in the thick-walled straight seam submerged arc welded steel pipe is the improper selection of welding process parameters. The welding process parameters of the thick-walled LSAW steel pipe mainly include: line energy welding current welding voltage welding speed welding wire spacing groove size etc.
夹渣是残留在焊缝内部的熔渣。从理论上分析，埋弧自动焊焊缝产生夹渣的原因主要有以下3点： Slag inclusions are slag that remains inside the weld. Theoretically the main reasons for slag inclusion in submerged arc automatic welding seams are as follows: ①原材料(包括母材、焊丝、焊剂)中夹杂物较多； ①There are many inclusions in raw materials (including base metal welding wire flux); ②多层焊时层间清理不干净； ②The cleaning between layers is not clean during multi-layer welding; ③选用的焊接工艺参数不当，不利于熔渣的浮出。 ③ The selected welding process parameters are inappropriate which is not conducive to the emergence of slag.
