在轻钢结构厂房中，C型钢应用极为广泛，其中在一些跨度较大、墙面门窗、窗框及墙梁处会采用C型钢双拼焊接的方式进行处理。下面来讲讲济南C型钢焊接热裂纹的原因及预防措施。

In light steel structure factories, C-shaped steel is widely used, and in some areas with large spans, walls, doors and windows, window frames, and wall beams, C-shaped steel double welding is used for treatment. Next, let's talk about the causes and preventive measures of hot cracks in Jinan C-beam welding.

热裂纹是指高温下所产生的裂纹，又称高温裂纹或结晶裂纹，通常产生在焊缝内部，有时也可能出现在热影响区，表现形式有：纵向裂纹、横向裂纹、根部裂纹弧坑裂纹和热影响区裂纹。

Hot cracks refer to cracks that occur at high temperatures, also known as high-temperature cracks or crystallization cracks. They usually occur inside the weld seam and may also occur in the heat affected zone. The manifestations include longitudinal cracks, transverse cracks, root crack crater cracks, and heat affected zone cracks.

其产生原因是由于焊接熔池在结晶过程中存在着偏析现象，低熔点共晶和杂质在结晶过程中以液态间层形式存在从而形成偏析，凝固以后强度也较低，当焊接应力足够大时，就会将液态间层或刚凝固不久的固态金属拉开形成裂纹。

The reason for its occurrence is due to the segregation phenomenon in the welding molten pool during the crystallization process. Low melting point eutectic and impurities exist in the form of liquid interlayer during the crystallization process, forming segregation. After solidification, the strength is also low. When the welding stress is large enough, the liquid interlayer or newly solidified solid metal will be pulled open to form cracks.

此外，如果母材的晶界上也存在有低熔点共晶和杂质，当焊接拉应力足够大时，也会被拉开。总之，热裂纹的产生是冶金因素和力学因素共同作用的结果。针对其产生原因，其预防措施如下：

In addition, if there are also low melting point eutectic and impurities on the grain boundaries of the base material, it will also be pulled apart when the welding tensile stress is large enough. In short, the generation of hot cracks is the result of the combined action of metallurgical and mechanical factors. The preventive measures for its causes are as follows:

（1）限制母材及焊接材料（包括焊条、焊丝、焊剂和保护气体）中易偏析元素和有害杂质的含量，特别应控制硫、磷的含量和降低含碳，一般用于焊接的钢材中硫的含量不应大于0.045%，磷的含量不应大于0.055%；另外钢材含碳量越离，焊接性能越差，一般焊缝中碳的含量控制在0.10%以下时，热裂纹敏感性可大大降低。

(1) Limit the content of easily segregated elements and harmful impurities in the base metal and welding materials (including welding rods, wires, fluxes, and shielding gases), especially control the content of sulfur and phosphorus and reduce carbon content. Generally, the sulfur content in steel used for welding should not exceed 0.045%, and the phosphorus content should not exceed 0.055%; In addition, the higher the carbon content of the steel, the poorer the welding performance. Generally, when the carbon content in the weld is controlled below 0.10%, the sensitivity to hot cracking can be greatly reduced.

（2）调整焊缝金属的化学成分，改善焊缝组织，细化焊缝品粒，以提高其塑性，减少或分散偏析程度，控制低熔点共品的有害影响。

(2) Adjust the chemical composition of the weld metal, improve the weld structure, refine the weld particles, improve their plasticity, reduce or disperse the degree of segregation, and control the harmful effects of low melting point alloys.

（3）采用碱性焊条或焊剂，以降低焊缝中的杂质含摄，改善结晶时的偏析程度。

(3) Use alkaline welding rods or fluxes to reduce impurities in the weld seam and improve the degree of segregation during crystallization.

佰富彩（4）适当提高焊缝的形状系数，采用多层多道焊接方法，避免线偏析，可防止线裂纹。

(4) Properly increasing the shape coefficient of the weld seam and adopting multi-layer and multi-pass welding methods to avoid centerline segregation can prevent centerline cracks.

（5）采用合理的焊接顺序和方向，采用较小的焊接线能超，整体预热和锤击法，收弧时填满弧坑等工艺措施。

(5) Adopting reasonable welding sequence and direction, adopting smaller welding line energy, overall preheating and hammering methods, and filling the arc crater during arc closure.

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