Introduction of Kunshan Joule laser -- the most commonly used welding process of 304 stainless steel pipe

In the laser welding industry, the use of laser welding stainless steel material workpiece manufacturers are very many, laser welding machine welding effect is also very good, 304 stainless steel material natural use of laser welding is also a very good choice.

304 stainless steel, as a kind of austenitic stainless steel, has good corrosion resistance, heat resistance and no magnetism. The corrosion resistance is better than that of 200 series stainless steel. It also has good high temperature resistance, good weldability, less sensitivity to welding cold cracks and hot cracks, good hot workability such as stamping and bending, no heat, and can be as high as 1000-1200 degrees.

In recent years, stainless steel has been widely used in aerospace, electronic devices, medical devices, nuclear industry, mechanical instruments and so on. Therefore, the packaging and welding of ultra-thin stainless steel products become very important. The traditional welding method is difficult to ensure the welding quality of sheet metal, and laser welding has the incomparable advantages of traditional welding, which can effectively reduce the welding defects. The research of 304 stainless steel welding technology is produced under this background.

In the process of using stainless steel, a large part of them need to be welded, because the welding quality directly affects the performance of stainless steel parts. Stainless steel welded joint consists of weld metal zone, heat affected zone and base metal zone.

1、 Advantages of laser welding for stainless steel

Compared with traditional welding, low power pulse laser seam welding has the advantages of high power density, concentrated energy, small heat input, narrow weld and small deformation. Moreover, after focusing the laser beam, a small spot can be obtained, which can be precisely positioned. These characteristics make laser seam welding more suitable for small size workpiece welding than other welding methods. For the laser welding of ultra-thin stainless steel, because the material is very thin, it is easy to vaporize and perforate, in order to get a continuous weld without burn through. The key is to control the parameters accurately.

Laser welding is based on the excellent directivity and high power density of laser beam. The laser beam is focused in a very small area by the optical system. In a very short time, a heat source area with highly concentrated energy is formed at the welded part, so that the welded object is melted and a firm solder joint and weld are formed.

There are two common laser welding methods: pulse laser welding and continuous laser welding. The former is mainly used for single point fixed continuous and thin material welding. The latter is mainly used for welding and cutting of large and thick parts.

2、 Characteristics of laser welding processing method:

1. Non contact machining, without pressure and surface treatment.

2. Small solder joint, high energy density, suitable for high speed machining.

3. Short time welding not only has no thermal effect on the outside world, but also has small thermal deformation and heat affected zone of the material itself. It is especially suitable for processing high melting point, high hardness and special materials.

4. There is no need for filler metal, no need for vacuum environment (can be directly carried out in the air), and no risk of X-ray generation in the air like electron beam.

5. Compared with the contact welding process, there is no wear consumption of electrodes, tools, etc.

6. No processing noise, no pollution to the environment.

7. Small workpieces can also be processed. In addition, it can be welded through the wall of transparent material.

8. It can realize long-distance and multi-channel simultaneous or time-sharing welding for parts that are difficult to reach by common methods through optical fiber.

9. It is easy to change the laser output focal length and solder joint position.

10. It's easy to carry on automata and robots.

11. The conductor with insulating layer can be directly welded, and the dissimilar metals with different properties can also be welded.

3、 The main parameters that affect the quality of laser welding are welding current, pulse width, pulse frequency and so on

1. With the increase of the current, the width of the weld increases, spatter gradually appears in the welding process, and the surface of the weld is oxidized and rough.

2. With the increase of pulse width, the width of weld is also increasing. The change of pulse width has a significant effect on the welding effect of laser welding machine for stainless steel ultra-thin plate. With the increase of pulse width, the sample may be oxidized and burned out.

3. With the increase of pulse frequency, the overlap ratio of solder joint increases, and the weld width increases at first, and then remains unchanged. Under the microscope, the weld is more and more smooth and beautiful. However, when the pulse frequency increases to a certain value, the welding spatter is serious, the weld becomes rough, and the upper and lower surfaces of the weldment are oxidized.

4. Positive defocusing is suitable for laser welding of ultra-thin plate. Under the same defocusing amount, the weld surface obtained by positive defocusing laser welding is smoother and more beautiful than that obtained by negative defocusing laser welding.

First, the cost of equipment: internationally, the price of ultrasonic welding machine and laser welding machine is the same, but Wuxi Nico, through the introduction of foreign technology and independent research and development, launched the full-automatic whole plate ultrasonic metal welding machine in the solar energy heat utilization industry, which completely broke the situation that China's ultrasonic welding equipment needs to rely on foreign imports, and basically reduced the price of domestic ultrasonic welding machine by half. The purchase cost of single equipment of ultrasonic metal welding machine is lower than that of laser welding machine, and the purchase ratio is usually 300000:1 million (now the price of domestic laser welding machine is also rapidly declining, about 700000). Laser welding machine is generally with two laser welding heads, ultrasonic machine is generally with one welding head. For the same production capacity, two ultrasonic welding machines are slightly better than one laser welding machine.

Second, the use cost: first, laser welding is suitable for thick materials, such as welding aluminum, and the thickness of aluminum plate is generally 0.4mm, while ultrasonic welding is suitable for thin products, such as aluminum plate, generally 0.2-0.3mm. In terms of welding materials, ultrasonic is superior. The second is the cost of consumable parts. The consumable parts of laser welding are xenon lamp and filter element. The consumable parts of ultrasonic welding are welding head. Generally speaking, laser welding consumables are cheaper than ultrasonic welding consumables. Therefore, ultrasonic metal welding is slightly better than laser welding.