How to clean fasteners correctly? When we use them, we should maintain them in time. For example, timing cleaning could improve their service efficiency. Let's share with you the way how to clean them. The main contents are as follows:
A. About the rinsing contamination of fasteners
Wash them with silicate-containing detergent and flush them afterwards after hardening. With infrared spectrum analysis the solid matters on the surface are proved to be inorganic silicates and iron oxide, which are caused by inadequate rinsing and the remnant silicate on the surface of fasteners.
B. The improper deposit of fasteners
The fasteners fade after drawing. Oily residues appear after immersion and evaporation which means they are high in fat. During the rinsing fasteners have been obviously contaminated by detergent and quenching oil. They melt under the heat treatment temperature with chemical burns, which indicates the squalor of the exterior of fasteners. The squalor are the mixture of base oil and ether in the quenching oil. The quenching oil could produce ether. By analyzing the quenching oil in the mesh belt furnace, we find that the low oxidation of fasteners in the quenching oil could be neglected because of their improper deposit in the process of heat. This is relating to cleaning and oil quenching.
C. The remnant on the external of fasteners
The white remnant on the high strength hex nut are proved to be phosphides by infrared spectrum analysis. If you haven't used the acid detergent and discover that the carbon solubility in the washing tank are high, you should pour out the liquids in the washing tank at fixed period and check out the concentration of lye in the washing tank.
D. The alkali burning of fasteners
1. The high strength hex nut blackens with remaining heat quenching and their appearance are in balanced black. But some places in the outside lane are visible to the naked eyes. And some places are in baby blue or blush. The raw materials and wire rods are painted with phosphate coating in case of need of cold impact. They could be directly heat treated without flushing. Cool them off in the quenching oil, clean them with alkali detergent and dry them, then draw them in 550 degree Celsius and heat the anti-rust oil in the drawing furnace. Thus the red spots appear on the screw thread.
2. The red particles in the bolts are caused by burning. In the process of heat treatment, chloride and calcium compound in the alkali detergent would burn and steel the fasteners and leave a mark on the surface of fasteners.
3. The quenching oil of steel fasteners should not be removed from the surface of alkali matters for it will keep the surface in high temperature austenization and cause it to be destroyed in the next drawing. Therefore you should clean and flush fasteners before the heat treatment to thoroughly clean out the alkali remnants so that the alkali burning is avoided.
E. The improper flushing of fasteners
It is common to quench larger fasteners with aqueous polymer solutions. Clean them with alkali detergent before hardening. After hardening, the inward parts of fasteners become rusted. This indicates that besides iron oxide sodium，gallium and sulfur are also there. It is certain that the inward parts of fasteners have alkali detergent, which maybe potassium hydroxide or sodium carbonate, or similar anti-rust substances. So it is necessary to clean the fasteners with water and exchange them regularly. This is also a good way to add anti-rust additive in the water.
F. The excessive corrosion of fasteners
Usually some black stripes are found on the high-strength fasteners. Through the flushing with organic and inorganic detergents the fasteners still have black stripes after quenching before heat treatment in the experiment. Even the larva, who have been carefully washed, would left spots after heat treatment. By analyzing the remnant contaminators with infrared spectrum analysis, we find that the sulfur and calcium are high-content. Get a piece of the fasteners, and scrub its black spots hard with filter paper of isopropanol acetic acid, leaving the spots on the paper. It is verified that the main elements on the paper are calcium, sulfur, iron, manganese and chromium and many more.