What problems will fasteners encounter during cleaning

1. There are signs of discoloration after tempering of fasteners, and oily residues will be found after soaking and volatilizing. In fact, this kind of substance is a high content of lipids, which indicates that the fastener is polluted by cleaning agent and quenching oil during rinsing, melts at heat treatment temperature and leaves chemical burn scars. This kind of substance proves that the surface of the fastener is not clean. The analysis results of quenching oil in mesh belt furnace confirm that the fasteners are slightly oxidized in quenching oil due to unreasonable stacking during heating, which is also related to the cleaning process.

2. There is white residue on the high-strength screw. We analyzed it with infrared spectrometer, and the results showed that these residues were phosphides. This indicates that the fasteners are not cleaned with acid cleaning agent and the concentration of alkali solution in the rinsing tank is not often detected.

3. Large size fasteners are often quenched with polymer aqueous solution. Before quenching, they are cleaned and rinsed with alkaline cleaning agent. The quenched fasteners have rusted on the inner side. In fact, in addition to iron oxide, there are sodium, potassium and sulfur, indicating that alkaline cleaning agent is adhered to the inner side of the fastener, which is likely to be potassium hydroxide, sodium carbonate or similar substances to promote its rusting.

4. Solid substances appear on the surface of fasteners. This is because the fasteners are not rinsed thoroughly, leaving silicate and iron oxide on the surface of the fasteners.