What are the treatment methods for blackening of internal hex socket head bolts? The processing technology of hex socket head bolts is different from that of general bolts. In addition to substrate processing technology, it is also suitable for large hexagonal heads, steel frame structures, etc. Blackening treatment refers to the use of specific treatment methods to produce a black surface oxide film on the inner hex socket head bolts, in order to improve its compressive strength. It is usually suitable for bolts above grade 8.8.
In fact, at room temperature, the colors of black raw materials and black materials are different. Black oxide film refers to the formation of a black or blue oxide film on the surface through processes such as acid washing, degreasing, heating, and oxidation. This processing method is suitable for indoor use with high-precision requirements and non replaceable components.
Compared with stainless steel, the metal treated with blackening on the surface of hex socket head bolts belongs to black metal, and the processing temperature is not high, which is generally less prone to deformation. Compared to stainless steel, its cost is lower. However, its rust prevention performance and decorative effect cannot be compared to stainless steel. When selecting metal materials to block air, a layer of oxide film will form on the surface of the inner hex socket head bolts after rust prevention treatment. If the appearance requirements are not high, black treatment can be chosen.
The surface of the hex socket bolt is treated with a black finish, also known as a slight blue finish. Blue treatment is a chemical surface treatment method that mainly generates a dense oxide film on the metal surface to prevent rusting and improve wear resistance. This treatment method is only applicable to the surface and will not affect the internal structure, which is different from alloy treatment methods such as quenching.
As is well known, all screws have grades, which are determined by the tensile strength and shear strength of the screws. The fracture of stainless steel screws may be due to tensile or shear forces exceeding the ultimate strength of stainless steel screws, unless there is a problem with the screws themselves.
Stainless steel screws usually refer to steel screws that can resist corrosion from air, water, acid, alkali salt, or other media. According to the different alloy compositions, stainless steel screws can focus on rust resistance or acid resistance. Although some steels have rust resistance, they may not necessarily have acid resistance, and acid resistant steels typically have rust resistance. The reasons for the fracture of stainless steel screws can be as follows:
Screw quality issue.
Insufficient screw strength.
The pre tightening torque of the screw is not appropriate.
The fatigue strength of screws is insufficient. Factors such as substandard material of screws, improper heat treatment, substandard product manufacturing process, unreasonable selection of stainless steel screws, and harsh usage environment can directly affect the fracture of screws.
