【 welding knowledge 】 the laser welding of stainless steel pipe welding method

Laser welding

In all of the steel pipe welding application, the edge of the steel strip to melt, when use the clamp bracket to edge of steel pipe extrusion to together, edge of solidification. For laser welding, however, the nature is its beam with high energy density. A laser beam to the surface of the molten material not only has produced a keyhole, and weld appearance is very narrow.

Power density is lower than 1 MW/cm2, such as GTAW technology, can't produce enough energy density keyhole to produce. In this way, no keyhole welding process get broad and shallow shape. Brought efficiency of penetration laser welding of high precision, this in turn reduced the grain growth, better metallurgical quality. GTAW, on the other hand, the higher the heat input and the slower cooling process resulted in the rough welding structure.

Generally speaking, it is considered that the laser is faster than GTAW welding process, they have the same rejection rate, while the former better metallurgical properties, and this brings the higher blasting strength and higher formability. When compared with the high frequency welding, laser processing material oxidation process does not occur, this makes the reject rate is lower and higher formability.

The influence of the spot size

In the welding of stainless steel pipe factory, welding depth is determined by the thickness of the steel pipe. In this way, the production goal is by reducing the welding width to improve formability, and to achieve higher speeds. When choosing the appropriate laser, people can not only consider the beam quality, must also consider the accuracy of the mill. In addition, the mill before the error size of work must also consider the limits of reducing speckle.

Many sizes in the steel pipe welding on the problem, however, is the main factors influencing the welding, the welding box (more specifically, welding volume) on the seams. Once the steel strip after forming for welding, weld features include: steel band gap, serious/slight dislocation welding, weld center line change. Clearance determines how much material is to be used for the formation of weld pool. The pressure is too big to steel pipe at the top or inside diameter excess material. On the other hand, severe dislocation or slight welding leads to poor weld appearance.

In addition, after welding box, steel tube will be further modification. This includes the size adjustment and shape (shape). Additional work, on the other hand, can remove some serious/slight weld defects, but may not be removed. Of course, we hope to achieve zero defect. In general, the rule of thumb is not more than five percent of the thickness of the material welding defects. More than this value, will affect the strength of the welding products.

The existence of the welding line for production of high quality stainless steel pipe is very important. As the car market is becoming more and more attention of formability, is directly related to a smaller heat affected zone (HAZ), and reduce the welding appearance. This, in turn, will promote the development of laser technology, namely improve beam quality to reduce spot size. With the smaller spot size, we need more focus on the Central Line scanning seam precision. Generally speaking, the steel pipe manufacturing chamber of commerce as far as possible reduce the deviation, but in fact, to 0.2 mm (0.008 inch) of deviation is difficult.