济南作为工业重镇，型钢焊接广泛应用于建筑钢结构、机械制造等领域。型钢焊接质量直接影响构件的承载能力与安全性，操作中需兼顾材料特性、工艺规范与环境因素，避免出现裂纹、未焊透等缺陷。掌握关键注意事项，是保障焊接构件长期稳定运行的基础。

　　As an industrial hub, Jinan's steel welding is widely used in fields such as building steel structures and machinery manufacturing. The welding quality of steel sections directly affects the load-bearing capacity and safety of components. During operation, it is necessary to consider material characteristics, process specifications, and environmental factors to avoid defects such as cracks and incomplete welding. Mastering key precautions is the foundation for ensuring the long-term stable operation of welded components.

　　焊接前的准备工作是保证焊接质量的前提，需从材料处理与设备检查两方面着手。型钢表面的锈迹、油污、氧化皮会影响焊缝结合力，焊接前需用角磨机搭配钢丝轮彻底打磨，露出金属光泽，尤其坡口两侧 50 毫米范围内需清理干净，若存在较深锈蚀坑，需补焊后再打磨平整。不同型号的型钢（如 H 型钢、工字钢、角钢）需采用对应坡口形式，厚壁型钢（厚度超过 10 毫米）宜开 V 形或 X 形坡口，坡口角度控制在 60°-70°，钝边厚度 2-3 毫米，确保焊条能深入坡口根部，避免未焊透；薄壁型钢可采用 I 形坡口，通过预留 1-2 毫米间隙保证熔深。焊接设备需提前调试，电焊机输出电流、电压应与焊条型号匹配（如碱性焊条需采用直流反接，电流根据焊条直径调整），焊钳、地线连接牢固，避免接触不良导致电流波动，影响焊缝成形。

　　The preparation work before welding is a prerequisite for ensuring welding quality, which needs to start from two aspects: material handling and equipment inspection. Rust, oil stains, and oxide scales on the surface of the steel section can affect the bonding strength of the weld seam. Before welding, it is necessary to thoroughly polish it with an angle grinder and a steel wire wheel to expose the metallic luster. Especially within a 50mm range on both sides of the groove, it needs to be cleaned thoroughly. If there are deep rust pits, they need to be repaired and polished flat after welding. Different types of steel (such as H-beams, I-beams, and angle steels) should adopt corresponding groove forms. Thick walled steel (with a thickness exceeding 10 millimeters) should have V-shaped or X-shaped grooves, with a groove angle controlled between 60 ° -70 ° and a blunt edge thickness of 2-3 millimeters, to ensure that the welding rod can penetrate deep into the groove root and avoid incomplete welding; Thin walled steel can adopt an I-shaped groove, with a reserved gap of 1-2 millimeters to ensure deep penetration. The welding equipment shall be debugged in advance. The output current and voltage of the electric welding machine shall match the model of the welding rod (for example, the alkaline welding rod shall adopt DC reverse connection, and the current shall be adjusted according to the diameter of the welding rod). The welding tongs and ground wires shall be firmly connected to avoid the current fluctuation caused by poor contact, which will affect the weld formation.

　　焊接过程中的工艺控制直接决定焊缝质量，需严格把控参数与操作手法。焊接电流是关键参数，电流过小会导致熔深不足，形成未焊透；电流过大则会造成咬边、烧穿，还会使合金元素烧损，降低焊缝强度。通常根据型钢厚度选择焊条直径（3.2 毫米焊条适合 6-10 毫米厚型钢，4 毫米焊条适合 10-20 毫米厚型钢），并匹配相应电流（100-130A 对应 3.2 毫米焊条，160-200A 对应 4 毫米焊条）。焊接速度需均匀稳定，手工电弧焊时每秒移动 3-5 毫米为宜，过快易造成焊缝窄而高，过慢则会导致焊缝过宽、晶粒粗大。多层多道焊时，每层焊完后需用角磨机清理焊渣与飞溅，检查无气孔、裂纹后再焊下一层，层间温度控制在 150-300℃（低碳钢），避免温度过高导致热影响区扩大，或温度过低产生冷裂纹。对于厚壁型钢的立焊与横焊，需采用短弧焊接，焊条角度与工件保持 45°-50°，通过小幅摆动确保坡口两侧熔合良好。

　　The process control during welding directly determines the quality of the weld seam, and strict control of parameters and operating techniques is required. Welding current is a key parameter, and too low a current can lead to insufficient penetration and incomplete welding; Excessive current can cause undercutting and burning through, as well as burn damage to alloy elements and reduce weld strength. Usually, the diameter of the welding rod is selected based on the thickness of the steel section (3.2mm welding rod is suitable for 6-10mm thick steel section, 4mm welding rod is suitable for 10-20mm thick steel section), and the corresponding current is matched (100-130A corresponds to 3.2mm welding rod, 160-200A corresponds to 4mm welding rod). The welding speed needs to be uniform and stable. It is advisable to move 3-5 millimeters per second during manual arc welding. If it is too fast, it can cause the weld seam to be narrow and high, while if it is too slow, it can cause the weld seam to be too wide and the grain to be coarse. When welding multiple layers and multiple passes, after each layer is welded, it is necessary to use an angle grinder to clean the welding slag and spatter, check for no pores or cracks, and then weld the next layer. The interlayer temperature should be controlled at 150-300 ℃ (low carbon steel) to avoid the expansion of the heat affected zone caused by high temperature or the occurrence of cold cracks caused by low temperature. For vertical and horizontal welding of thick walled steel, short arc welding is required, with the welding rod angle kept at 45 ° -50 ° to the workpiece, and a small swing to ensure good fusion on both sides of the groove.

　　环境因素对型钢焊接质量影响显著，需采取针对性防护措施。济南夏季高温高湿，焊接时空气中的水汽易进入熔池形成气孔，此时需对焊条进行烘干（酸性焊条经 150℃烘干 1 小时，碱性焊条经 350℃烘干 1-2 小时），烘干后存入 80-100℃保温筒，随用随取，避免再次吸潮。冬季低温环境（低于 0℃）会降低焊缝冷却速度，导致淬硬组织产生，引发裂纹，焊接前需对型钢进行预热，用氧乙炔焰均匀加热坡口及两侧 100 毫米范围，预热温度达到 80-150℃（根据钢种调整），并保持层间温度不低于预热温度。大风天气（风速超过 8 米 / 秒）会吹散电弧周围的保护气体（手工电弧焊虽无保护气体，但强风会导致电弧不稳），需搭建临时防风棚，确保焊接区域风速控制在允许范围内。

　　Environmental factors have a significant impact on the welding quality of steel sections, and targeted protective measures need to be taken. Jinan has high temperature and humidity in summer, and water vapor in the air during welding is prone to enter the molten pool and form pores. At this time, the welding rods need to be dried (acidic welding rods are dried at 150 ℃ for 1 hour, and alkaline welding rods are dried at 350 ℃ for 1-2 hours), and then stored in an 80-100 ℃ insulation cylinder for immediate use to avoid moisture absorption again. The low temperature environment in winter (below 0 ℃) will reduce the cooling rate of the weld seam, leading to the formation of hardened structure and causing cracks. Before welding, the section steel needs to be preheated by uniformly heating the groove and both sides within a range of 100mm with an oxyacetylene flame. The preheating temperature should reach 80-150 ℃ (adjusted according to the steel type), and the interlayer temperature should not be lower than the preheating temperature. Strong wind weather (with wind speeds exceeding 8 meters per second) can blow away the protective gas around the arc (although manual arc welding does not have protective gas, strong winds can cause unstable arc), and temporary windproof shelters need to be built to ensure that the wind speed in the welding area is controlled within the allowable range.

　　不同类型型钢的焊接需采用差异化策略，适应其结构特点。H 型钢焊接重点关注翼缘板与腹板的连接，采用船形焊或横焊方式，焊脚尺寸按设计要求确定（通常为型钢厚度的 0.7 倍），避免因焊脚过大导致腹板变形。工字钢对接时，需保证上下翼缘与腹板对齐，错边量不超过 1 毫米，焊接顺序应先焊腹板对接缝，再焊翼缘对接缝，减少焊接应力导致的弯曲变形。角钢焊接常出现的问题是焊后角度变形，可采用对称焊接法（从角钢两侧交替施焊），或在焊接前用夹具固定，焊后缓慢冷却，待应力释放后再拆除夹具。对于异种型钢连接（如 H 型钢与角钢焊接），需根据两者厚度选择焊条，厚侧宜采用多层焊，薄侧控制焊接电流，避免烧穿。

　　Different welding strategies should be adopted for different types of steel to adapt to their structural characteristics. The focus of H-beam welding is on the connection between the flange plate and the web plate, using ship welding or transverse welding methods. The size of the weld leg is determined according to the design requirements (usually 0.7 times the thickness of the steel section) to avoid deformation of the web plate due to excessive weld leg size. When connecting I-beams, it is necessary to ensure that the upper and lower flanges are aligned with the web plate, with a misalignment of no more than 1 millimeter. The welding sequence should be to weld the web plate butt joint first, and then the flange butt joint to reduce bending deformation caused by welding stress. The common problem with angle steel welding is angle deformation after welding. Symmetrical welding method (alternating welding from both sides of the angle steel) can be used, or the fixture can be fixed before welding, slowly cooled after welding, and the fixture can be removed after the stress is released. For dissimilar steel connections (such as welding H-beams and angle steels), the welding rod should be selected according to the thickness of both. Multi layer welding should be used for the thick side, and the welding current should be controlled for the thin side to avoid burning through.

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