The processing technology of high-strength bolts is different from ordinary bolts. In addition to the most basic manufacturing process, there is also a heat treatment process. Widely used in large hexagonal head bolts, also known as large hexagonal head bolts and steel frame structure bolts. High-strength blackened bolts refer to bolts with a strength level above 8.8 after blackening treatment. What is blackening treatment? Let's take a look. 1. In fact, at room temperature, the color of black raw materials is different from that of black raw materials. 2. Blackening refers to pickling passivation, degreasing, heating and air oxidation on the reflective surface to form a black or blue oxide film. The bolt gauge is accurate and cannot be replaced. There are many applications in the room. The surface of the high-toughness blackened bolt forms an oxide layer, and the ambient temperature during processing is not too high, so it generally does not deform. Compared with stainless steel, it is naturally much cheaper, but its rust resistance and decorative arts are worse than stainless steel. 3. After the metal material is used to protect the gas and prevent rust, a layer of oxide film will also be formed on the surface of the high-strength bolts. If the appearance is not required, blackening treatment can be adopted. The surface of construction steel is blackened, also known as some dark blue. Dark Blue Solution is an organic chemical surface solution. Its core function is to produce a dense oxide film on the surface of the workpiece to prevent corrosion and corrosion. In order to ensure the wear resistance of the workpiece, it is only a surface treatment and will not have any impact on the internal structure. This is not a heat treatment process, it is fundamentally different from heat treatment. When installing high-strength bolts, in what order should they be assembled? The high-strength bolts in a connecting head need to be gradually assembled from the middle of the bolt group and tightened one by one. The initial tightening, re-tightening, and final tightening all need to be tightened gradually from the middle of the bolt group to the surroundings one by one. Each tightening is marked with different colors of paint to avoid missing tightening. If the joints are connected by high-strength bolts or arc welding, they must be tightened first and then welded by electric welding. They should be arranged in the order specified by the design points. If there is no requirement in the design, the sequence of construction technology shall be arranged according to the construction technology sequence of first tightening and then electric welding (that is, first bolting and then welding), and the high-strength bolts shall be screwed first and then electric welding and welding. The tightening sequence of high-strength bolts is carried out from the part with the largest bending stiffness to the free end that is not restrained, and the same connection point is inclined to the surroundings, so that the plates can be closely bonded.