Surface cleaning of ductile iron castings

Surface cleaning of ductile iron castings

1. Dust on the surface of ductile iron castings

The production of steel castings is often carried out in dusty places, where there is often a lot of dust in the air that continuously falls on the surface of the equipment. They can be removed with water or alkaline solution. However, sticky dirt requires high-pressure water or steam for cleaning.

2. Surface floating iron powder or embedded iron on ductile iron castings

On any surface, free iron will rust and corrode stainless steel. Therefore, floating powder generally falls off with dust. Having a certain degree of adhesion is considered as embedded iron. In addition to dust, there are many sources of surface iron, including cleaning with ordinary carbon steel wire brushes and shot peening with sand, glass beads, or other abrasives, which were previously used for grinding ordinary carbon steel, low alloy steel, or cast iron, or stainless steel products near non stainless steel parts and equipment mentioned above. If stainless steel is not protected during cutting or lifting, the wire ropes, lifting tools, and irons on the working surface are easily embedded or dirty.

Ordering requirements and post factory inspections can prevent and detect the presence of free iron. The ASTM standard A380 specifies a corrosion test method for inspecting iron or steel particles on the surface of stainless steel. When iron free is required, this testing method should be used. If the result is satisfactory, clean the surface with clean purified water or nitric acid until the dark blue color disappears.

As stated in standard A380, if the rust prevention test solution is not completely clean, it is not recommended to use this test method on the technical surface of the equipment, that is, for direct contact surfaces used in the production of human consumer goods.

A simpler testing method is to expose it to water for 12 to 24 hours to check for rust spots. This test is not very sensitive and time-consuming. These are testing methods, not cleaning methods. If iron is found, please use the chemical method described later. And electrochemical cleaning.

3. Scratches on ductile iron castings

Mechanical cleaning of scratches and other rough surfaces to prevent the accumulation of process lubricants or products and/or dirt.

4. Rust spots on ductile iron castings

Stainless steel products or equipment may sometimes rust before or during production, indicating severe surface contamination. Before putting the equipment into use, rust removal should be carried out, and the cleaned surface should be inspected by iron and/or water testing.

5. Rough grinding and machining

Grinding and machining can both cause surface roughness with defects such as grooves, overlaps, and burrs. Each defect can also seriously damage the metal surface, to the extent that the damaged metal surface cannot be cleaned by acid washing, electrolytic polishing, or shot peening. Cleaning. A rough surface may become a source of corrosion and deposition products. Before re welding, clean the weld defects or excess weld reinforcement ribs and do not use rough grinding for polishing. In the latter case, fine abrasive should be used for grinding.

Precision machining