The surface heat treatment of seamless steel pipe is a metal heat treatment process that changes the mechanical properties of the surface layer by heating and cooling the surface of the steel pipe. Surface quenching is the main content of surface heat treatment, and its purpose is to obtain a high-hardness surface layer and favorable internal stress distribution to improve the wear resistance and fatigue resistance of steel pipes.
1. Surface hardening
The seamless steel pipe is heated rapidly by different heat sources, and is cooled rapidly when the surface temperature reaches above the critical point, so that the surface layer of the seamless steel pipe obtains a hardened structure while the core maintains the original structure. In order to achieve the purpose of only heating the surface of the steel pipe, the heat source used is required to have a high energy density. According to different heating methods, surface hardening can be divided into induction heating (high frequency, intermediate frequency, power frequency) surface hardening, flame heating surface hardening, electric contact heating surface hardening, electrolyte heating surface hardening, laser heating surface hardening, electron beam surface hardening . The most widely used in industry is induction heating and flame heating surface hardening.
2. Chemical heat treatment
Place the steel pipe in a medium containing active elements to heat and keep warm, so that the active atoms in the medium can penetrate into the surface of the workpiece or form a covering layer of a certain compound. To change the structure and chemical composition of the surface, so that the surface of the steel pipe has special mechanical or physical and chemical properties. Usually, other suitable heat treatments are required before and after chemical infiltration, so as to maximize the potential of the infiltration layer and achieve the best cooperation between the steel pipe core and the surface layer in terms of structure and performance. According to the different infiltrated elements, chemical heat treatment can be divided into carburizing, nitriding, boronizing, siliconizing, sulfurizing, aluminizing, chromizing, zincizing, carbonitriding, aluminum-chromizing and so on.
Surface heat treatment is one of the important processes in seamless pipe manufacturing. Compared with other processing techniques, heat treatment generally does not change the shape and overall chemical composition of the workpiece, but endows or improves the performance of seamless pipes by changing the microstructure inside the workpiece or changing the chemical composition of the steel pipe surface.
1. Surface hardening
The seamless steel pipe is heated rapidly by different heat sources, and is cooled rapidly when the surface temperature reaches above the critical point, so that the surface layer of the seamless steel pipe obtains a hardened structure while the core maintains the original structure. In order to achieve the purpose of only heating the surface of the steel pipe, the heat source used is required to have a high energy density. According to different heating methods, surface hardening can be divided into induction heating (high frequency, intermediate frequency, power frequency) surface hardening, flame heating surface hardening, electric contact heating surface hardening, electrolyte heating surface hardening, laser heating surface hardening, electron beam surface hardening . The most widely used in industry is induction heating and flame heating surface hardening.
2. Chemical heat treatment
Place the steel pipe in a medium containing active elements to heat and keep warm, so that the active atoms in the medium can penetrate into the surface of the workpiece or form a covering layer of a certain compound. To change the structure and chemical composition of the surface, so that the surface of the steel pipe has special mechanical or physical and chemical properties. Usually, other suitable heat treatments are required before and after chemical infiltration, so as to maximize the potential of the infiltration layer and achieve the best cooperation between the steel pipe core and the surface layer in terms of structure and performance. According to the different infiltrated elements, chemical heat treatment can be divided into carburizing, nitriding, boronizing, siliconizing, sulfurizing, aluminizing, chromizing, zincizing, carbonitriding, aluminum-chromizing and so on.
Surface heat treatment is one of the important processes in seamless pipe manufacturing. Compared with other processing techniques, heat treatment generally does not change the shape and overall chemical composition of the workpiece, but endows or improves the performance of seamless pipes by changing the microstructure inside the workpiece or changing the chemical composition of the steel pipe surface.
