What are the mechanical properties of hot-rolled seamless pipes?
Hot-rolled seamless pipes have excellent mechanical properties, and their tensile strength is usually between 400-600MPa, and their yield strength can reach more than 245MPa. Due to the hot rolling process, the steel grains are refined, so that the pipes have both good strength and toughness. Compared with cold-rolled pipes, hot-rolled seamless pipes have higher elongation and can withstand greater plastic deformation. These characteristics make them particularly suitable for high-pressure and high-load working environments. In addition, hot-rolled seamless pipes have low anisotropy and have stable mechanical properties in all directions.
What is the corrosion resistance of hot-rolled seamless pipes?
The basic corrosion resistance of hot-rolled seamless pipes depends on their material, and the corrosion resistance of ordinary carbon steel pipes is relatively limited. In a humid or corrosive environment, an oxide layer is easily formed on the surface of hot-rolled seamless pipes, which can slow down the corrosion rate to a certain extent. In order to improve corrosion resistance, hot-rolled seamless pipes are usually subjected to surface treatments such as galvanizing, spraying or painting. For special environments, hot-rolled seamless pipes made of alloy steel or stainless steel can be selected. It is worth noting that the hot rolling process itself will form oxide scale on the surface of the pipe, which requires subsequent treatment to improve its corrosion resistance.
What is the dimensional accuracy of hot-rolled seamless pipes?
The dimensional accuracy of hot-rolled seamless pipes can usually reach ±1% outer diameter tolerance and ±12.5% wall thickness tolerance. Due to the thermal expansion and contraction effect, the dimensional control difficulty of hot rolling process is greater than that of cold rolling process. For applications with high precision requirements, hot-rolled seamless pipes often require subsequent cold processing to improve dimensional accuracy. The ovality control of large-diameter hot-rolled seamless pipes is also an important indicator. With the advancement of modern rolling technology, the dimensional accuracy of hot-rolled seamless pipes is constantly improving.
What is the welding performance of hot-rolled seamless pipes?
Hot-rolled seamless pipes usually have good welding performance, especially hot-rolled seamless pipes made of low carbon steel. When welding, it is necessary to pay attention to the microstructural changes in the heat-affected zone, which may cause welding stress. For alloy steel hot-rolled seamless pipes, preheating and post-weld heat treatment may be required to ensure welding quality. Hot-rolled seamless pipes have no welds, so there will be no problem of performance differences between the weld zone and the parent material during welding. Selecting the right welding materials and process parameters is the key to ensuring welding quality.
What is the high temperature resistance of hot-rolled seamless pipes?
The long-term use temperature of ordinary carbon steel hot-rolled seamless pipes generally does not exceed 450°C. In high temperature environments, hot-rolled seamless pipes may experience creep, affecting their service life. For high temperature applications, hot-rolled seamless pipes made of special materials such as chromium-molybdenum alloy steel are usually selected. The oxidation resistance of hot-rolled seamless pipes at high temperatures is also an important consideration. Through reasonable material selection and heat treatment processes, the high temperature resistance of hot-rolled seamless pipes can be significantly improved.
