Defects such as metal oxidation, porosity and cracks often occur during the welding repair of aluminum welding strip cast aluminum parts. Therefore, the following points should be noted during the welding repair process:

 

1. Welding electrode used for welding repair is not suitable for direct use. It should be baking at 150~160℃ for 2h to remove water and reduce hydrogen pores in the weld.

 

2. Horizontal swing should not be made during welding operation to avoid oxidation of welding parts due to overheating.The welding rod should be perpendicular to the surface of the welding piece, and make a straight line round trip along the welding direction, so that the weld metal in the liquid state for a longer time, conducive to hydrogen from the molten pool escape.

 

3. When starting arc or joint, the arc should not be too short, so as to avoid bonding or bad fusion between welding rod and welding parts. By increasing arc length, the welding rod end can produce droplet injection, with better welding effect;Welding arc should not be too long, should be controlled between 5~6mm, too long arc will make metal droplet oxidation fast, big splash, easy to form pores and other defects;At the end of welding, slowly extinguish the arc by filling the crater.

 

4. The melting speed of the aluminum welding rod is fast, so the feeding speed of the welding rod should be adjusted to the melting speed of the welding rod.

 

5. When welding and repairing the casting with defect depth less than 20mm, the defect can be shoveled into a v-shaped groove of 60°~70°. It is required that the processed groove should not exceed 24h, and welding and repairing should be carried out immediately.

 

6. It is not suitable to use larger welding current and thicker electrode diameter during welding repair of al-Mg alloy castings, otherwise welding pieces are prone to collapse or excessive alloy element burning.

 

7. When there are multiple cracks in cast aluminum, the small cracks should be repaired first and then the big cracks should be repaired.Long cracks should be welded in sections, each section length is 60~70mm, first from the middle of the crack to one end, then back to the middle of the crack to the other end.

 

8. In order to improve the microstructure of weld metal and eliminate welding residual stress, the cast aluminum should undergo an overall annealing treatment of 300~350℃ after welding, and then slow cooling.

 

9. Multi-layer welding repair should be carried out to remove slag layer by layer, so as not to cause slag inclusion of welding seam.

 

10. After the whole welding work is finished, flush the slag and spatter on the surface of the welding piece with steam or hot water to avoid corrosion of the welding piece.

 

11. Common aluminum welding strips are: pure aluminum welding strip L109;Aluminum silicon alloy electrode L209;Aluminum-manganese alloy electrode L309;Al - Mg alloy electrode L409, etc.For casting aluminum parts with unknown components, especially imported parts, it is also possible to make aluminum welding strips by melting the original material to match the welding material.

 

12, it is worth noting that, due to the aluminum alloy electrode is extremely susceptible to moisture, it is difficult to keep, in addition to the relatively poor welding quality, is now basically eliminated.