Treatment Method For Sanitary Pipe Fittings

Advantages and disadvantage of Hot rolling and cold rolling of stainless steel

Hot rolling and cold rolling are the two most commonly used processes for forming steel or steel plates. They are also the most basic steel processing methods.

Hot rolling and cold rolling

This two treatments can have a great impact on the structure and performance of stainless steel. The rolling stress of steel is based on hot rolling. Cold rolling is mainly only used for the production of small sections and thin plates.


I. Hot rolled for sanitary pipe fittings

Advantage:

It can destroy the casting structure of the steel ingot, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is dense and the mechanical properties are improved. This improvement is manifested in the upward direction of the rolling, so that the steel is no longer isotropic to a certain extent; the bubbles, cracks and looseness formed during casting can also be welded under the action of high temperature and pressure.

Disadvantages:

 

  • 1. After hot rolling, the non-metallic mixture (tension is sulfide and oxide, and silicate) inside the steel is pressed into thin sheets, and signs of delamination (interlayer) appear. Delamination greatly deteriorates the tensile properties of the steel along the thickness direction, and interlayer tearing may occur when the weld is tightened. The local strain induced by weld shrinkage often reaches several times the yield point strain, which is much larger than the strain caused by the load.
  • 2. The dross stress caused by uneven cooling. The dross stress is the internal self-balanced stress without external force. Hot-rolled steel sections of various cross-sections have such dross stress. The larger the section size of ordinary steel, the greater the dross stress. Although the dross stress is self-balanced, it still has a positive effect on the performance of steel components under external forces. Such as deformation, stability, resistance to fatigue, etc., may have unlucky effects.

II, Cold rolling for sanitary pipe fitting

It refers to the steel plate or steel strip processed into various types of steel by cold drawing, cold bending, and cold drawing at room temperature.

Advantages:

Unlike Hot rolling cold rolling has fast forming speed, high output, and without damaging the coating, it can be made into a variety of cross-sectional forms to meet the needs of utilization conditions; cold rolling can cause large plastic deformations in the steel, thereby improving the steel Yield point.

Disadvantages:

 

  • 1. Although there is no thermal plastic compression during the forming process, slag stress still exists in the section, which affects the characteristics of the steel group and local buckling.
  • 2. The style of cold-rolled steel is usually an open section, which makes the free rotation stiffness of the section low. It is easy to rotate when being bent, and bend torsional buckling when being pressed, and its torsion resistance is poor.
  • 3. The wall thickness of cold-rolled steel is small, and the corners where the plates are joined are not thickened, and the load is weak.