SAWH steel pipe in the proportion in recent years, stable at 42% to 45%, the pipe on the rise. SAWH steel pipe compared with the reliability of materials and adaptable species, especially adapted to the production of thick steel and alloy steel.
The main problem is the high investment, high cost and complex manufacturing process, wall thickness and ovality tolerances. The welded pipe is actually a plate of deep-processed products, the price of similar conditions, the spiral steel pipe market competitiveness and improve its reliability, with the continuous improvement of quality steel plate and pipe technology and equipment level, part of the spiral steel occupy the market, there is the possibility of welding pipe replacement, but this is only a very limited area. Spiral Pipe thermal fatigue reliability generally refers to work in hot and cold alternating crack under the action of the ability to resist. As the cold, heat generated by alternating thermal fatigue crack called crack.
In the mold die casting mold, forging mold scrapped the main reason is easy to produce thermal fatigue reliability is poor thermal fatigue cracks. For the die steel, its stability is mainly determined by the thermal fatigue of steel toughness and strength. Therefore, thermal fatigue and good stability tool steel must have good toughness and high strength (wet strength) is a good match. Usually made of steel into a variety of materials used when the processes are often one that is cold, heat exchange, the exchange, the steel will output some of the cracks, and different steel on the number of these cracks is it different for steel against the ability of this role is called the thermal fatigue reliability. As the spiral steel pipe from the raw materials, therefore, spiral steel pipe will have a stable thermal fatigue, thermal fatigue for the good stability of the spiral steel pipe will have better toughness and strength.
Reduce the carbon content, can effectively improve the weldability of steel pipe; reduce the sulfur content ofsteel pipe to improve the toughness of injection and crack beneficial, can reduce the build-sulfide inclusions to improve the crack resistance of steel, At the same time, reduce the sulfur content of steel can improve the surface quality. Phosphorus for the steel toughness and weldability are harmful, and other common elements in steel compared to the strong increase of phosphorus Charpy impact transition temperature grams of strong hardening effect is also to reduce the phosphorus content can directly improve weldability, because some hot-rolled steel strip in the phosphorus content as low as possible.
