Three welding forms of weld seam

After the very narrow area of the edge of the tube blank is heated to a high temperature of 1250~1300°C, the two edges of the tube blank are squeezed together by the large extrusion force transmitted by the extrusion roller to form a co-crystallization and achieve welding, solid-phase welding The characteristic is that although the edge of the tube blank has reached the welding temperature, the heating area of the edge of the tube blank in the corner area of the opening is very narrow, and it still maintains its original shape, and only a small amount of metal is extruded during the welding process, forming a tiny The internal and external burrs, the flying sparks are small, and the height of the burrs is generally not higher than 30mm.

solid solution welding
The performance reflected on the edge of the tube blank is that the edge of the tube blank is heated to 1300~1400°C, and the physical shape of the tube blank edge in the opening corner area is no longer sharp and angular, especially near the apex of the corner, and the contours of the two edges have been blurred At the same time, the heated area is much wider than that of the solid phase, and welding can be completed as long as a large extrusion force is required. In this process, part of the molten metal is extruded to form larger internal and external burrs, accompanied by more Big sparks fly everywhere.

fusion welding
The edge of the tube blank is heated above 1400°C, the heating range of the edge widens sharply, part of the metal is in a molten state, and the physical shape loses its regularity. The molten metal on both sides of the front end of the opening angle has "flowed" together to form a liquid lintel. The current is highly concentrated at the lintel, resulting in partial gasification of the molten metal at the lintel. In this state, the two edges of the tube blank can be welded with a small extrusion force. At the same time, a large amount of molten metal is easily Extrusion produces a large number of internal and external burrs, accompanied by strong sparks flying.
In the actual production process, these three welding forms are often intertwined. However, the solid-solution welding form is more favored by operators and is used more frequently. The application risks of the two forms of solid-phase welding and fusion welding are very high. Large, under the influence of many objective factors, the actual welding temperature is difficult to be strictly constant: in the state of solid phase welding, if the temperature is slightly lower, it will be impenetrable and form cold welding, and in the state of molten welding, if the temperature is a little higher , it will form over-burning defects. On the other hand, when the welding temperature is high or low, the above problems will not occur, and it is easy to meet the process needs. Especially if the customer requires a straight-use tube with small internal burrs, solid If welding with small internal burrs is required, solid solution welding should be selected; of course, if welding high-strength thick-walled pipes, then fusion welding is a better choice.