There is stress in the steel pipe, no matter where it is, it will cause the steel pipe to crack during quenching. Generally, in the production process, after the heat treatment, a cooling process is required. If the cooling is too fast or incomplete, it will also cause cracks on the surface of the steel pipe. Moreover, if the local area is not cooled in place, problems such as cross-section will occur, mainly due to the residual stress molecules inside the steel pipe.
At the cracks of the steel pipe, the cracks begin to appear in the center of the cross-section and expand rapidly from the inside to the outside. Generally, in order to avoid such cracks, the water and oil double liquid quenching process is used during quenching. When the process is in production, the high-temperature parts can achieve rapid cooling, so as to ensure that the outer layer of the steel pipe gets enough martensite, and the rapid cooling will also cause stress. Thick-walled seamless steel pipes are divided into two types: round and special-shaped according to the cross-sectional shape. Special-shaped pipes have square, elliptical, triangular, hexagonal, melon seed, star, and finned pipes. Seamless steel pipe manufacturers Seamless steel pipes are widely used. General-purpose seamless steel pipes are rolled from ordinary carbon structural steel, low-alloy structural steel or alloy structural steel, with a large output, and are mainly used as pipelines or structural parts for conveying fluids. According to different purposes, it is divided into three types of supply: a. According to chemical composition and mechanical properties; b. According to mechanical properties; c. According to hydraulic test. Steel pipes supplied according to categories a and b, if used to withstand liquid pressure, shall also be subjected to a hydraulic test. 3. Special-purpose seamless pipes include seamless pipes for boilers, chemical and electric power, seamless steel pipes for geology, and seamless pipes for petroleum. Therefore, the slow cooling method is used when cooling, which can reduce the temperature difference on the surface of the steel pipe, and prevent the central part of the steel pipe from shrinking, which can reduce the stress well and avoid the occurrence of quenching cracks.
The cooling rate during quenching can be said to be a very important factor that determines the quality of the steel pipe. Seamless steel pipe manufacturers Seamless steel pipes have a hollow section and are used in large quantities as pipelines for conveying fluids, such as pipelines for conveying oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter in flexural and torsional strength and is an economical section steel. Therefore, during quenching, in order to ensure the quality, the cooling rate is usually accelerated during the high temperature forging process. The premise is that this rate must exceed the critical quenching cooling rate, so that it can be used in the steel pipe The surface of the steel tube forms a martensite structure, and this method can also offset the thermal stress value inside the steel pipe. Thus, it is possible to reduce the occurrence of cracks on the surface of the steel pipe due to stress.
Tips:ASTM A53 seamless and welded steel pipe is a general, all-purpose pipe used in generator plants, refineries, compressor stations, natural gas transmission, and steam conduction. It is acceptable for welding, flanging, and bending.