濟南作為工業重鎮，型鋼焊接廣泛應用于建筑鋼結構、機械制造等領域。型鋼焊接質量直接影響構件的承載能力與安全性，操作中需兼顧材料特性、工藝規范與環境因素，避免出現裂紋、未焊透等缺陷。掌握關鍵注意事項，是保障焊接構件長期穩定運行的基礎。

　　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.

　　焊接前的準備工作是保證焊接質量的前提，需從材料處理與設備檢查兩方面著手。型鋼表面的銹跡、油污、氧化皮會影響焊縫結合力，焊接前需用角磨機搭配鋼絲輪徹底打磨，露出金屬光澤，尤其坡口兩側 50 毫米范圍內需清理干凈，若存在較深銹蝕坑，需補焊后再打磨平整。不同型號的型鋼（如 H 型鋼、工字鋼、角鋼）需采用對應坡口形式，厚壁型鋼（厚度超過 10 毫米）宜開 V 形或 X 形坡口，坡口角度控制在 60°-70°，鈍邊厚度 2-3 毫米，確保焊條能深入坡口根部，避免未焊透；薄壁型鋼可采用 I 形坡口，通過預留 1-2 毫米間隙保證熔深。焊接設備需提前調試，電焊機輸出電流、電壓應與焊條型號匹配（如堿性焊條需采用直流反接，電流根據焊條直徑調整），焊鉗、地線連接牢固，避免接觸不良導致電流波動，影響焊縫成形。

　　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.

　　焊接過程中的工藝控制直接決定焊縫質量，需嚴格把控參數與操作手法。焊接電流是關鍵參數，電流過小會導致熔深不足，形成未焊透；電流過大則會造成咬邊、燒穿，還會使合金元素燒損，降低焊縫強度。通常根據型鋼厚度選擇焊條直徑（3.2 毫米焊條適合 6-10 毫米厚型鋼，4 毫米焊條適合 10-20 毫米厚型鋼），并匹配相應電流（100-130A 對應 3.2 毫米焊條，160-200A 對應 4 毫米焊條）。焊接速度需均勻穩定，手工電弧焊時每秒移動 3-5 毫米為宜，過快易造成焊縫窄而高，過慢則會導致焊縫過寬、晶粒粗大。多層多道焊時，每層焊完后需用角磨機清理焊渣與飛濺，檢查無氣孔、裂紋后再焊下一層，層間溫度控制在 150-300℃（低碳鋼），避免溫度過高導致熱影響區擴大，或溫度過低產生冷裂紋。對于厚壁型鋼的立焊與橫焊，需采用短弧焊接，焊條角度與工件保持 45°-50°，通過小幅擺動確保坡口兩側熔合良好。

　　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.

　　環境因素對型鋼焊接質量影響顯著，需采取針對性防護措施。濟南夏季高溫高濕，焊接時空氣中的水汽易進入熔池形成氣孔，此時需對焊條進行烘干（酸性焊條經 150℃烘干 1 小時，堿性焊條經 350℃烘干 1-2 小時），烘干后存入 80-100℃保溫筒，隨用隨取，避免再次吸潮。冬季低溫環境（低于 0℃）會降低焊縫冷卻速度，導致淬硬組織產生，引發裂紋，焊接前需對型鋼進行預熱，用氧乙炔焰均勻加熱坡口及兩側 100 毫米范圍，預熱溫度達到 80-150℃（根據鋼種調整），并保持層間溫度不低于預熱溫度。大風天氣（風速超過 8 米 / 秒）會吹散電弧周圍的保護氣體（手工電弧焊雖無保護氣體，但強風會導致電弧不穩），需搭建臨時防風棚，確保焊接區域風速控制在允許范圍內。

　　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.

　　不同類型型鋼的焊接需采用差異化策略，適應其結構特點。H 型鋼焊接重點關注翼緣板與腹板的連接，采用船形焊或橫焊方式，焊腳尺寸按設計要求確定（通常為型鋼厚度的 0.7 倍），避免因焊腳過大導致腹板變形。工字鋼對接時，需保證上下翼緣與腹板對齊，錯邊量不超過 1 毫米，焊接順序應先焊腹板對接縫，再焊翼緣對接縫，減少焊接應力導致的彎曲變形。角鋼焊接常出現的問題是焊后角度變形，可采用對稱焊接法（從角鋼兩側交替施焊），或在焊接前用夾具固定，焊后緩慢冷卻，待應力釋放后再拆除夾具。對于異種型鋼連接（如 H 型鋼與角鋼焊接），需根據兩者厚度選擇焊條，厚側宜采用多層焊，薄側控制焊接電流，避免燒穿。

　　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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