We sent four delegates to Paris. ...
15 Mei 2012, 14:36
What Causes Corrosion ...
04 Mei 2012, 14:47
Factors Affecting the Quality Galvaniz ...
Factors Affecting the Quality Galvanized & and Preservation
There are several factors that affect the properties of steel galvanizer in providing quality products and reliability, namely:
1. Condition of the surface of the workpiece (steel): Painted, galvanized rust or have previously.
Steel which is very rusty, will long for the pickle and the rust on the surface of the steel will still imprint on the surface so that it will cause the galvanizing defects.
Galvanized steel has to be in stripping before the galvanized. This can be done effectively, but requires an additional fee for the use of more acid and also special handling. Therefore the use of components that have been galvanized for fabrication should be avoided.
2. Metallurgy of Steel
Galvanized coating is formed by the reaction between the steel with galvanized zinc temperature. Metallurgy of steel and steel surface conditions will also affect the thickness and appearance of the galvanized.
composition of Steel
Silicon or phosphorus contained in a steel can both significantly affect the structure, appearance and properties of the galvanized coating. In cases of extreme layer can be very thick, brittle and easily damaged.
As shown in the chart below, the levels of certain silicon will produce a very thick layer. A very thick layer is the result of the increased reactivity of zinc degan molten steel, and the formation of zinc-iron coating the steel surface quickly. The graph shows that the combination of accelerated growth of the thickness of galvanizing occur during the silicon content is between 0:04 to 0:14%.
The growth rate will be reduced in content between the 0:15 and 0.22%, and increased with increasing silicon content above 0.22%.
The presence of phosphorus above the threshold at 0.05% caused an increase in the reactivity of the steel with zinc coating liquid and the formation of the fast. When combined with silicon, phosphorus can cause effects that are not proportional to the thickness of which is excessive rise in the galvanized coating.
The feasibility of silicon steel / phosphor for galvanized
For eligibility guidelines silicon steel / phosphor for galvanized criteria are as follows:
Levels of silicon (Si) <0.04% and
Levels of silicon (Si) + (2.5 x% P) <0.09%
Galvanized coatings on silicon steel is usually dull gray or pale with a slightly rough surface and may be fragile. The resistance of the layer is proportional to the thickness of the galvanized coating and is not influenced by appearance. In general, thickness, adhesion and appearance of the galvanized coating on steel silicon and phosphorus are beyond the control of the galvanizer.
3. Quality Welding
Welding quality design and workmanship relating to the direct effect on the quality of galvanizing. Welding wire is generally high levels of silicon and this can cause the metal parts are welded with zinc reacts more intensely than other parts, resulting in a thicker galvanized coatings on metal parts are welded.
If aesthetic welding overlooked here where the former welding must difinis essentially flush with the surface after the galvanized metal, it must use a wire welding of low-grade silicone and has the same metallurgical composition of the metal base.
Welding design is a function of the location of welding and expansion. Welding is less dense liquid chemical process can allow penetration into the joints. The trapped liquid will boil into steam at the surface causes kerukan in hot dip.
Remnants of flux crystals are left in the joints of air will absorb moisture and cause rust and corrosion galvanized after it is installed at the field.
The surface tension (surface tension) of liquid zinc dalah such a way that he could not penetrate into the gaps of less than 1 mm in diameter. some material is welded in submerged arc welding flux may contain small particles that are generally less than 1 mm in diameter are melted together into a groove weld surface. These particles are ceramic and not consumed by pickling and will cause pinholes in the galvanized coating on the groove weld. Because of the small diameter, the pinholes is not affecting the durability of the galvanized coating. If the presence of pinholes is not desirable for aesthetic reasons it must be done at the welding abrasive blasting to remove these particles.
In the MIG welding will leave a thin layer of slag on the weld-lasannya. This layer must be removed before because it would cause damage to galvanized coatings on galvanized welded parts. Welding sparks attached to the material to be removed anyway because it will cause problems of aesthetics after galvanized.
Welding quality will affect the quality of the galvanized coating. Poor welding will cause the chemical liquid penetration into the joints and then flow out after the object is mounted so that it can damage the part.
Welding slag left in the pickling liquid cleaning will prevent the passage and also will prevent the action of liquid zinc with that part. Galvanized coating will not stick to this part and the damage is beyond the control of the Galvanizers.