Prevent the lock on the problem of locking fasteners
Fastener users often reflect why stainless steel fasteners are sometimes locked, and in the use of carbon steel fasteners do not often happen when a similar phenomenon is not stainless steel fasteners material is soft, carbon steel Fasteners relatively hard reason? Yes! Stainless steel and carbon steel are essentially different. Stainless steel has a good ductility, but its hardness and carbon steel have a certain gap. Austenitic stainless steel grade 316 head A4-80 hardness can only be achieved in the equivalent of carbon steel hardness rating of 8.8. However, this argument can only be said to be half.
Locking (Thread Galling, or killed) often occurs in stainless steel, aluminum and titanium alloy fasteners, these types of metal alloy itself has anti-corrosion characteristics, will be damaged in the surface, the metal The surface produces a thin layer of oxide (in terms of austenitic stainless steel, is chromium oxide) to prevent further deeper corrosion. When the stainless steel fasteners are locked, the pressure and heat generated between the teeth will destroy and erase the chromium oxide layer between them, making the metal tooth pattern directly blocked / cut, and then the phenomenon of adhesion. When the adhesive phenomenon continues to occur (usually not more than one lap full diameter), will make the stainless steel fasteners completely locked, no longer can be removed or locked. Usually this series of blocking → shearing → sticking → locking a series of actions takes place in just a few seconds. Therefore, to understand the characteristics of stainless steel products and follow the correct procedures are to prevent the first step in the lock of stainless steel fasteners.

The external cause of the lock
1, did not correctly select the product before use should first confirm whether the mechanical properties of the product to meet the needs (such as the tensile strength of screws and nuts safety load). In addition, the length of the screw should be chosen to tighten the exposed nuts to one or two teeth.
2, tooth pattern rough or a foreign body sticky if there are solder joints and other metal chips caught in the teeth, often lead to lock.
3, too hard or too fast to try to use a torque wrench or socket wrench, to avoid the use of wrenches or electric wrenches. Because the electric wrench often leads to the lock speed too fast, the temperature rises rapidly and locked.
4, force the direction of the angle of the wrong nut must be perpendicular to the screw axis of rotation, do not tilt.
5, the use of notch washers / retaining ring can effectively prevent the use of too tight lock problem.

Prevents the prevention of stainless steel fasteners
1, in the use of stainless steel fasteners, is always a fixed speed to lock the nut?
If you are the first to use or are not familiar with the stainless steel product process users, you should consult your supplier about the relevant characteristics of stainless steel. Generally speaking, slowing the speed of locking will be able to significantly reduce (or even completely avoid) the chance of locking. Because, heat often occurs when the lock, so when the heat increases, the chance of locking will also increase. In use, the speed of locking stainless steel fasteners should be less than the speed of carbon steel.
2, in the lock before the first lubrication screw or nut?
If the answer is "no", it is recommended to use butter, molybdenum disulfide, graphite, mica or talc to lubricate the teeth inside and outside to reduce the occurrence of locking. The coating is also an effective way to lubricate the nuts that have been deducted, as if there were a layer of lubricant between the nut and the screw.
3, whether to use the same material grade screws and nuts?
If the answer is yes, you can recommend using different grades of screws and nuts, such as 304 with 316 and so on. But should pay attention to the choice of stainless steel grade or to meet their own anti-rust corrosion needs.
In addition, when locking the flange is the most common case of locking. Assuming you have noticed and acted on the above points, including the use of gaskets, the use of gaskets, and the use of longer nuts, such as GB6710 or DIN934, diagonally on the nut, slowly Appropriate tightness, etc., if still can not be resolved, often in the pre-lock after unloading, and finally, had to ask you in the pre-locking flange device when the first use of carbon steel nut, until the last official lock and then use Stainless steel nuts, in the beautiful rust-resistant and do not lock to find a balance between