Main performance of stainless steel welding performance

It is welded with stainless steel, non-toxic, non polluting, argon arc welding process, equipped with multiple universal wheels, capable of all-round movement and braking, making it easy to move and park. Both sides of the body open doors, making cleaning more convenient, greatly reducing the generation and diffusion of noise. LED lighting is added to make it more beautiful and energy-saving. The new generation of improved equipment is also equipped with a top air duct, and the side air vent stops the progress, so that the purification is more sufficient. The fan stops to control the air volume by grades. Grades 1-3 enable smoke to be discharged in large, medium and small sizes, making it easier to control. The energy saving and consumption reduction are more obvious. The wind resistance is less than 70Pa, and the operating noise is less than 40dB. The upper part is a barbecue board and a lampblack outlet, and the lower part is a built-in electrostatic lampblack purifier. The lampblack collected from the lampblack outlet is disposed by the purifier, and then the clean gas is discharged from the chimney in front of the barbecue oven.

Main performance of stainless steel welding performance

(1) High temperature crack

The high-temperature crack mentioned here refers to the crack related to welding. High temperature cracks can be roughly divided into solidification cracks, microcracks, HAZ (heat affected zone) cracks and reheat cracks.

(2) Low temperature crack

Low temperature cracks sometimes occur in martensitic stainless steels and some ferritic stainless steels with martensitic structure. Because the main reasons for its generation are hydrogen diffusion, the restraint degree of welded joints and the hardening structure in them, the disposal methods are mainly to reduce hydrogen diffusion during welding, appropriately suspend preheating and post weld heat treatment, and reduce the restraint degree.

(3) Toughness of welded joints

In order to reduce the high temperature crack sensitivity in austenitic stainless steel, 5% - io% ferrite remains in the composition design. However, the existence of these ferrites leads to the drop of low-temperature toughness. When the duplex stainless steel discontinues welding, the amount of austenite in the welding joint area decreases, which affects the toughness. In addition, with the increase of ferrite, the toughness value has a significant downward trend

It has been proved that the reason why the toughness of welded joints of high purity ferritic stainless steel decreases significantly is due to the mixing of carbon, nitrogen and oxygen. The chloride type inclusions are formed after the oxygen content in the welded joints of some steels increases, which become the source of crack onset or the path of crack propagation, making the toughness drop. Some steels are mixed with air in the maintenance gas, in which the ammonia content increases and produces lath like Cr2N on the {100} surface of the matrix cleavage surface, making the matrix harden and making the toughness drop.

(4) B phase embrittlement

Austenitic stainless copper, ferritic stainless steel and duplex stainless steel are prone to embrittlement of b phase. Due to a few percent of b phase precipitated in the structure, the toughness decreases significantly. O phase is usually precipitated at 600~900 ℃, especially at 750 ℃. As a preventive measure to prevent the formation of b phase, the content of iron cord in austenitic stainless steel should be reduced as much as possible.

(5) 475 ℃ embrittlement

Stainless steel with a chromium content of more than 15.5%, when heated for a long time at 475 ℃ (370-540 ℃), will often show an increase in strength and a significant decrease in toughness, accompanied by a decrease in corrosion resistance. Because this phenomenon is most common when the heating temperature is 475 ℃ (about 475 ℃), it is called 475 ℃ brittleness.

Since the chromium content of stainless steel is mostly above 15.5%, the welding heat during welding must also pass through the range of 370~540 ℃. If the welding is not properly controlled, the stay time in the range of 370~540 ℃ is too long, and some martensitic stainless steel austenitic stainless steel, ferritic stainless steel, duplex stainless steel and precipitation hardening stainless steel with high chromium content will show 475 ℃ embrittlement. The systematic study points out that after the embrittlement treatment at 475 ℃, the steel is not only cold brittle, but also hot brittle (the impact toughness below 800 ℃ is lower than that without embrittlement). The degree of embrittlement increases with the increase of chromium content. When the chromium content is below 15.5%, there is no tendency of embrittlement. When the carbon content is within the range of 0.04%~0.28%, there is no obvious difference in the degree of embrittlement.