Hardness of Galvanized Steel Pipe

Galvanized steel pipe is a steel pipe that has been coated with zinc. This coating protects the steel from corrosion. It is most commonly used for outdoor construction like fences and handrails, or for some interior plumbing. The zinc provides a barrier against corrosion so that the pipe may be exposed to the outdoor environmental elements. The protective barrier proves equally effective against damage from indoor humidity.

Galvanized steel can be made into a strong plumbing or tubing material — one that resists corrosion from exposure to water or the elements. It has been used used for water-supply pipes or as a strong tubing for outdoor applications.

Galvanized steel hardness

Galvanized Steel are those steel that has been covered with a layer of zinc metal. Galvanized steel in terms of hardness test is a Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, micro-hardness and high-temperature hardness, etc., which can be divided into a variety, most of the manufacturers or using a Buchner,Rockwell, Vickers hardness of these three methods.

Brinell hardness measurement principle is the test force F (N) with a certain size, the diameter D (mm) of hardened steel balls or carbide ball pressed into the surface of the metal under test, to maintain a predetermined time after the drop test force, the the indentation average diameter d (mm) measured with a reading microscope, and then the equation Brinell hardness HB value, or the value d from the prepared Brinell hardness table to detect HB Brinell hardness measurement method is suitable for cast iron, non-alloy, annealing and quenching and tempering steel, the determination should not be too hard, too small, too thin and the surface does not allow the larger indentation specimen or workpiece.

Rockwell hardness test when the sample is too small or Brinell hardness (HB) is greater than 450, to switch to a Rockwell hardness measurement. The test method is an apex angle of 120 degrees with a diamond cone or the diameter 1.59mm/3.18mm the ball, pressed into the surface of the material under a certain load, the hardness of the material by the indentation depth obtained.

The Vickers hardness means a standard of the hardness of the material. Vickers hardness there is a small negative Vickers hardness test load 1.961 <49.03N, it applies to a thinner workpiece, the tool surface or coating hardness measurement; micro-Vickers hardness test load <1.961N applicable to the metal foil, , of the ultra-thin surface layer hardness measurement.

Defects Of Welded Steel Pipe

Defects Of Welded Steel Pipe

Welded steel pipe production process is a steel sheet,strip,and other various molding methods using the straight press roll helical direction curling into a desired cross-sectional shape,and then by means of heart,prssure,different methods of welding weld weld together to obtain steel.Therefore,defects in the welded steel pipe is divided into two parts:the steel base material defects and weld defects.

1.Steel base material defect
The sheet material defects after rolling and other processes,most of planar,parallel to the surface;their main weakness delamination,cracks,folds,etc.,which is the most common layered internal defects.Stratification will produce a variety of cracks when the tensile stress perpendicular to the surface of the sheet by the hierarchical will seriously affect the strength of the steel pipe,it is not allowed defects.

2.Weld defects
Weld defects refers to defect during welding or after welding resulting in the weld is divided into cracks,proes,slag,incomplete penetration,incomplete fusion,undercut weld defects.Intensive weld porosity,slag,etc.a dense three-dimensional defects,cracks,lack of fusion and other  defects in the case of the flat,great harm.Strip slag.