First, what are the cutting operations for S355JRH seamless steel pipe?
(1) Flame cutting: S355JRH seamless steel pipe can be flame cut. Its chemical composition allows it to maintain relatively stable performance under high-temperature flames. During flame cutting, attention should be paid to adjusting the flame intensity and cutting speed. For example, in oxy-acetylene flame cutting, appropriate oxygen pressure and acetylene flow rate can ensure a smooth cut surface. However, after flame cutting, a certain heat-affected zone may be generated at the cutting edge, requiring appropriate post-processing, such as grinding, to remove the oxide and hardened layers.
(2) Plasma cutting: This cutting method is also suitable for S355JRH seamless steel pipe. The high temperature of the plasma arc can quickly melt the seamless steel pipe material for cutting. Its cutting speed is faster than flame cutting, and the cutting accuracy is higher. However, plasma cutting generates a large amount of heat, which may cause changes in the microstructure of the cutting edge. Therefore, attention should also be paid to quality inspection and the necessary treatment of the cutting edge.
(3) Laser Cutting: Laser cutting of S355JRH seamless steel pipes offers advantages such as high precision and high speed. The energy density of the focused laser beam is extremely high, enabling the seamless steel pipe material to melt and vaporize rapidly, achieving precise cutting. It can cut complex shapes with good surface quality and a small heat-affected zone. However, laser cutting equipment is expensive and requires highly skilled operators.
Second, what are the details of the bending processing for S355JRH seamless steel pipes?
(1) Cold Bending: S355JRH seamless steel pipes have certain cold-bending properties. During cold bending, due to the characteristics of its yield strength and elongation, the seamless steel pipe can withstand bending deformation to a certain extent without cracking. However, care must be taken not to make the bending radius too small during cold bending, otherwise it will lead to excessive thinning of the outer wall of the seamless steel pipe or even cracks. Generally, there is a corresponding recommended minimum bending radius value based on the outer diameter and wall thickness of the seamless steel pipe.
(2) Hot Bending: If a large degree of bending is required or the seamless steel pipe has a large specification, hot bending is an option. By heating seamless steel pipes to a certain temperature (generally above the recrystallization temperature of the steel), the yield strength of the steel can be reduced, making it easier to bend. During hot bending, precise control of the heating temperature and bending speed is necessary to ensure that the shape and dimensions of the bent seamless steel pipe meet requirements and to avoid defects such as wrinkles on the surface of the seamless steel pipe due to excessively high temperature or bending speed.
Third, what should be noted in the welding process of S355JRH seamless steel pipes?
(1) Good welding performance: The chemical composition of S355JRH seamless steel pipes determines their good welding performance. Its moderate carbon content and appropriate alloying elements allow for good fusion of the weld metal and the base metal during welding. For example, when using manual arc welding, suitable welding rods can be selected, such as the E50 series welding rods, whose chemical composition and mechanical properties match those of S355JRH seamless steel pipes, ensuring weld quality.
(2) Pre-welding preparation requirements: Before welding, the welding area of the seamless steel pipe needs to be cleaned to remove oil, rust, and other impurities to ensure welding quality. Meanwhile, for thicker seamless steel pipes, preheating treatment may be necessary to reduce welding stress and prevent welding cracks. The preheating temperature is generally determined based on the thickness of the seamless steel pipe and the welding process, typically around 100-150℃.
(3) Post-weld treatment: After welding, post-weld heat treatment may be necessary to eliminate welding stress. For example, for some important welded structures, tempering can be used, heating the welded seamless steel pipe to a certain temperature (e.g., 550-650℃) and then slowly cooling it. This can improve the toughness and fatigue resistance of the weld joint.
Fourth, what are the details of the turning process for S355JRH seamless steel pipes?
During turning processing, S355JRH seamless steel pipes, due to their balance of hardness and toughness, can achieve good surface quality. During the turning process, the key is to rationally select the tool material, tool geometry parameters, and cutting parameters. For example, using carbide cutting tools and selecting appropriate geometric parameters such as rake angle, clearance angle, and inclination angle, as well as suitable cutting speed, feed rate, and depth of cut, can effectively improve turning efficiency and machining quality. Meanwhile, because seamless steel pipes are hollow, care must be taken with the clamping method during turning to prevent deformation.
Post time: Jan-23-2026