Bronze gas welding operation points

     Bronze gas welding process and operation should pay attention to the following problems:

1) Preparation before welding. Before gas welding, the defects such as shrinkage, looseness, and falling sand of the casting should be shoveled, and the groove of 60 ° ~ 70 ° should be shoveled and the depth of the shovel should be until the metal base metal is in good condition. Before the weld repair crack, the start and end points of the crack should be found. When the weld penetration defect or the cracked workpiece is prone to copper leakage, the bottom of the weld repair may be padded or sealed with a back cover. The repaired bronze parts must be properly leveled to prevent deformation during welding.

2) Gas welding of tin bronze. Because of the brittleness of tin bronze at high temperatures, it must not be subjected to impact during the welding process except for preheating at 350~450 °C. Do not move immediately after welding.

    When tin bronze is used for gas welding, the welding wire can be made of the same material as the base material, but it is preferable to make the tin content higher than the base material by 1% to 2% (mass fraction) to supplement the burning loss of tin during the welding process, or to contain A bronze material of deoxidizing elements such as phosphorus, silicon, and manganese. The gas welding flux is the same as that when welding pure copper, and the air agent 301 (CJ301) is used .

    Gas solder bronze should be strictly neutral flame, the flame energy rate is the same as when welding carbon steel. The position of the flame is slightly higher than that of the welded carbon steel, and the distance between the flame core and the surface of the weldment is ≥ 10 mm . The operation process is basically the same as when gas welding pure copper. After welding, the weld can be hammered or annealed to eliminate welding residual stress and improve the mechanical properties and compactness of the weld.

3) Repair welding of aluminum bronze. Before the gas welding, the aluminum oxide film can be removed by using a flux of aluminum gas (air agent 401 ). In addition, the gasification film can also be removed mechanically.

    When welding aluminum bronze, the welding wire adopts the same welding wire as the base material; preheating should be preheated to 500~600 °C before welding; the flame energy rate should be larger; the neutral flame is used, and the flame flame is 7~10mm away from the surface of the weldment. When repairing several defects on a casting, the biggest defects should be repaired first, and then the small defects should be repaired. This is because the weldment has been preheated to some extent when the repair is large, so it is compared. Easy to repair small defects.

    When repairing long and deep defects, it is best to tilt the workpiece by 45 ° and then perform up-slope welding, because single-pass welding can be used to ensure the quality of the welded joint.