Quality factor of Polished 304 rectangular 2 inch tube tubing

Polished 304 rectangular 2 inch tube tubing is a common material, and its quality is often affected by some factors, such as billet, roll speed, solution treatment and welding temperature, which are all things that everyone needs to pay attention to.

1. Rough: Polished 304 rectangular 2 inch tube tubing blank, the molten steel is supplied by electric arc furnace or intermediate frequency furnace and refined in AOD furnace, and decarburized by oxygen blowing in AOD furnace. In this way, gas inclusions in the molten steel float to the slag layer. In actual operation, sometimes too much oxygen is blown in, and iron silicon is added for reduction, but more silica inclusions are produced.

2. Rolling speed: The stainless steel seamless pipe is made of round billets for two-roll cross-rolling and perforation, during which the metal flows outward to form holes. When the rolling speed is too fast, the hole forming speed exceeds the advance speed of the blank, causing the inner hole and the mandrel to separate without contact. In addition, in the process of perforation deformation, the inner hole is not compressed, and inner hole cracks are easily generated.

3. Solution treatment: To change the outer diameter and wall thickness of the stainless steel seamless pipe through cold drawing, cold rolling and other processes, it is necessary to eliminate cold drawing by solid solution, and work hardening after cold rolling. In order to avoid the bending of the steel pipe, some factories cool the steel pipe slowly after solid solution, and the carbides do not dissolve in the austenite grains and precipitate at the grain boundaries. When the metal is deformed again, the hard carbide precipitates become the deformation resistance, and cracks are prone to occur during cold drawing and cold rolling.

4. Welding temperature: After the stainless steel continuous casting slab is hot rolled into a steel plate, it becomes a stainless steel welded pipe after bending and vertical welding. The welding temperature is too high, the thick wall is not welded with a layer, and the wet towel is not covered after welding to cool. The slow cooling of the weld and heat-affected zone from high temperature greatly reduces the toughness of the weld and heat-affected zone and causes weld cracks.