The SPCC material in the welded steel pipes that people usually use is more prominent, but the quality of welded pipes is also divided into good and bad. People must select dignifiedly when selecting welded pipes. The following is a detailed explanation of the quality evaluation methods of welded pipes.
The welded pipe itself has the unique ability to resist corrosion and acid-base chemicals. It can be equipped with organic chemistry differently from the reducing agent. Its surface layer has a thin but very dense air. The oxide film has short and long effects and often resists redox reactions in more ways. In the whole process of steel rolling, there will be surface cracks in the welded pipe. The surface cracks can be divided into several types:
1). Welded steel pipe cracks traverse the thickness of the cast slab, and the cracks in the equiaxed crystal zone at the center of the tube are fine cracks along the grain boundary. The cracks on the inner arc side usually crack parallel line cracks, and the cracks on the outer arc side usually follow the cracks. Crystal cracks.
2) The cracks along the grain boundary are in-situ stress cracks, and the cracking cracks are the cracks that traverse the crystals destructively and are the result of external forces. Suppose what countermeasures must be taken to deal with this kind of cracked state? The following is a detailed explanation for everyone:
1. Improve the arc precision of the casting machine to prevent excessive ground stress on the heterogeneous page in the early stage of freezing and avoid cracks along the grain boundary.
2. Use methods such as moderately accelerating the forging rate and expanding the cooling water flow, increasing the water flow, and reducing the temperature within a certain range to maintain forced cooling.
3. Strictly control the steel composition of the alloy layout, especially in the control of carbon and water content.
4. Improve the electromagnetic induction mixing of rolled steel, and control the superheat of the molten steel in the tundish below 40℃.
