Welding Technology for Grid Steel



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1. welding process design

Determine the welding method, welding parameters and welding rod, welding wire, flux specification models, etc..

 

2. spot welding

Welding structure in the splicing, assembly to determine the precise location of the parts, the first spot welding. The length and thickness of the spot welding shall be determined by calculation. The current should be more than 10%~15%, and the position of the spot welding should be avoided as far as possible to avoid the stress concentration of the end part and the corner of the component.

 

3. electrode baking

The welding rod and the powder core welding wire must be baked in accordance with the quality requirements before baking, low hydrogen electrode after baking, should be placed in the heat preservation box with the use of.

 

4. preheating before welding

Preheating can reduce the cooling rate of the heat affected zone, and prevent the generation of welding delay cracks. Preheating zone on both sides of the weld, the width of each side should be more than 1.5 times the thickness of the welding parts, and should not be less than 100mm.

 

5. post weld heat treatment

Post weld heat treatment is mainly to the welding seam for dehydrogenation treatment, in order to prevent the generation of cold crack. After heat treatment should be carried out immediately after welding, heat preservation time should be determined according to the thickness of the plate according to the thickness of 25mm plate 1h. Preheating and post heat can be used to distribute the flame gun. 

 

6. welding sequence determination

The general began to expand from around the welding seam center; first welding shrinkage, after weld shrinkage; as symmetrical welding; weld intersection, weld longitudinal seam, after cooling to room temperature, then weld transverse weld; thick plate welding layer.