Seamless steel pipes have become very common in life, so do you know that seamless steel pipes can be divided into several grades?
First, the surface of a general hot-rolled seamless steel pipe product is FA, and the seamless steel pipe product after pickling is FB. The quality of cold rolled seamless steel pipe is
Ordinary seamless steel pipe products are not required on the surface, such as the inner panel of the car, with the FB surface, for some of the outer panels of the car that are not particularly high in requirements, use FC. For high-end cars, use FD surface.
Usually the pickled seamless steel pipe product is the FB surface, so it can replace the cold rolled product to make some structural parts.
There are fewer processes in the back, which can save costs for the company, and the surface of the scale is removed, and it is easy to solder.
Relatively speaking, compared with hot-rolled products, pickling products are easier to weld. If oiling, lacquering, etc. are followed, it is easier and the quality is better.
Reports such as China's seamless pipe network: In addition, the dimensional accuracy is much better than that of hot-rolled products, and the dimensional accuracy is relatively high compared to hot-rolled seamless steel pipe products. Moreover, the pickled products are flat, the layout is better, the unevenness and so on are better. Surface finish is much better than hot rolled products, and the appearance is higher
45 steel is a high-quality carbon structural steel, the hardness is not high and easy to cut, the mold is commonly used as a template, a tip, a guide column, etc., but heat treatment.
45# steel is widely used in machinery manufacturing, and the steel has good mechanical properties. But this is a medium carbon steel, the quenching performance is not good, 45 steel can be hardened to HRC42~46. Therefore, if surface hardness is required, and it is desired to exert the superior mechanical properties of 45# steel, the surface of 45# steel is often carburized and quenched, so that the required surface hardness can be obtained.
Before the steel is quenched, the hardness is greater than HRC55 (up to HRC62).
The highest hardness for practical application is HRC55 (high frequency quenching HRC58).
Steel should not be subjected to a heat treatment process of carburizing and quenching.
After quenching and tempering, the parts have good comprehensive mechanical properties and are widely used in various important structural parts, especially those connecting rods, bolts, gears and shafts that work under alternating load. However, the surface hardness is low and it is not wear resistant. Tempering + surface quenching can be used to improve the surface hardness of the part.
Such a report on China's seamless pipe network: carburizing is generally used for heavy-duty parts with surface wear resistance and core impact resistance, and its wear resistance is higher than quenching and tempering + surface quenching. The surface has a carbon content of 0.8--1.2%, and the core is generally 0.1--0.25% (in a special case, 0.35%). After heat treatment, the surface can obtain high hardness (HRC58--62), low core hardness and impact resistance.
