The head of the St52 hydraulic cylinder tube is a semi-spherical ball head. The small hole 2mm is 28mm deep from the center of the head, and then quenched. After quenching, the oxide layer inside the small hole is difficult to remove. Which expert helped me, the oxide layer on the outer surface, I can remove it, the key is the oxide layer inside the two large holes, it is difficult to remove!
The purpose of quenching the rolling tube is to make the martensite or bainite transformation of the supercooled austenite. I don't need to introduce this conversion to convert all the objects, and it is not just surface conversion.
For the oxide surface of the metal surface, the simple method is pickling. In the same acidic solution, the metal oxide is preferentially reflected, that is, you only need to control the time, such as thirty seconds, one minute. Remove the item, wash it, and remove surface acid. Thus, the oxide film is generally etched away.
A rolling tube is a steel pipe material that has been treated by cold drawing or hot rolling. Because the inner and outer walls of the steel pipe have no oxide layer, high pressure and no leakage, high precision, high smoothness, no deformation of cold bending, flaring, flattening without cracks, etc., it is mainly used to produce pneumatic or hydraulic components, such as cylinders or cylinders. It can be a seamless tube. The chemical components of the honing pipe are carbon C, silicon Si, manganese Mn, sulfur S, phosphorus P, and chromium Cr.