The commonly used materials for self-tapping screws are stainless steel and carbon steel. Generally speaking, the difficult problem of carbon steel self-tapping screws in cleaning is often that after heat treatment and tempering, the main problem is that the rinsing is not clean. The lye remains on the surface due to unreasonable screw stacking, causing surface corrosion, alkali burns or sudden fire, improper oil selection and rust on the surface of fasteners.
1. Unreasonable stacking of screws. Carbon steel screws show signs of discoloration after tempering, indicating that the fasteners are contaminated by cleaning agents and quenching during the rinsing period, and melt at the heat treatment temperature, leaving chemical burn scars. This substance is confirmed to be tight. The surface of the firmware is dirty.
2. Improper rinsing. For large-size carbon steel self-tapping screws, they are often quenched with polymer aqueous solution. Before quenching, they are cleaned and rinsed with alkaline cleaning agent. After quenching, the fasteners have rusted on the inside.
Analysis with a red spectrometer confirmed that in addition to iron oxide, there is sodium, indicating that there is an alkaline cleaning agent on the inside of the carbon steel self-tapping screw, which is likely to be carbon or similar, which promotes its rust. Rinse the screws to check whether there is excessive contamination, and it is also recommended to change the rinse water frequently. In addition, adding a rust-like agent to the water is also a good way.
In short, everyone should pay attention to these points when cleaning self-tapping screws.
