How can duplex steel achieve "biphasic strength and toughness"?

        In heavy industrial fields such as petrochemicals, Marine engineering, and energy transmission, flanges, as the core components of pipeline connections, are subject to extreme working conditions such as high pressure, high temperature, and strong corrosion for a long time. However, traditional carbon steel or stainless steel flanges are prone to cracking, leakage, corrosion and failure in harsh environments, which not only leads to equipment shutdown for maintenance, but also may cause safety accidents. Facing the current conditions, Longquan Industrial, with over two decades of technological accumulation in the field of duplex steel flanges, redefines the performance standards of flanges with the "duplex strength and toughness" characteristic, providing more reliable and durable solutions for global customers.

The biphasic structure creates a "combination of rigidity and flexibility"

        Traditional flanges mostly use single austenitic or ferritic stainless steel, making it difficult to balance corrosion resistance and tensile strength. Longquan Industrial's duplex steel flanges (such as SAF 2205, SAF 2507) achieve a perfect balance between strength and toughness through a unique "austenite + ferrite" duplex microstructure. Its ferritic phase offers high yield strength (≥620MPa), while the austenitic phase endows it with excellent resistance to stress corrosion cracking. Especially in corrosive media containing chloride ions, hydrogen sulfide, etc., its corrosion resistance is more than three times higher than that of traditional 316L stainless steel.

        In a certain Middle East oilfield project, the customer reported that the average service life of traditional flanges in sulfur-containing well fluid was only six months, while Longquan duplex steel flanges had been in continuous operation for three years without corrosion leakage, directly reducing maintenance costs by over 70%.

Double guarantee of precision forging and heat treatment

        To fully leverage the performance advantages of duplex steel, Longquan Industrial independently developed the "low-temperature forging + temperature-controlled solution treatment" process. The forging temperature is strictly controlled at 1050℃-1150℃ to avoid grain coarsening. The solution treatment adopts staged cooling technology to ensure that the ratio of the two phases is precisely controlled at 50:50±5%. This major technological breakthrough has enabled the flange to pass the intergranular corrosion resistance performance (ASTM A262 Practice E) at 100%, and the impact toughness (AKV) remains ≥80J even in an environment of -40℃, far exceeding the industry standard.

        A certain European chemical enterprise once suffered from pipeline leakage due to the brittle fracture of flanges at low temperatures. After switching to Longquan duplex steel flanges, it has been operating continuously for two years in an extremely cold environment of -50℃ without any failure. The customer praised it as "redefining reliability in severe cold conditions".

All-round protection from the deep sea to high temperatures

        In the field of Marine engineering, Longquan duplex steel flanges have passed the DNV GL certification and have been successfully applied to the 300-meter deepwater oil and gas platform in the South China Sea. Its resistance rate to seawater corrosion (ISO 9227) is lower than 0.01mm/ year. Combined with the patented sealing structure design, it still maintains zero leakage under the impact of high-pressure water hammer.

        In high-temperature refining and chemical scenarios, a domestic oil refinery adopted Longquan duplex steel flanges to replace traditional carbon steel flanges. Under a high-temperature environment of 450℃ and a high-pressure environment of 25MPa, the creep rate of the flanges decreased by 60%, and the service life was extended from 18 months to over 5 years.

Cost reduction and efficiency improvement can benefit both enterprises and customers

        Choosing Longquan duplex steel flanges is not just about purchasing a product, but also about buying a set of solutions. The purchasing director of a certain international engineering company said. By reducing the frequency of flange replacement, lowering the risk of leakage and shortening the downtime, the overall cost for customers can be reduced by 40% to 60%. At present, Longquan Industrial has provided over 500,000 duplex steel flanges to more than 80 countries around the world, covering leading enterprises such as BP, Shell and petrochina.

        Longquan Industrial holds international certifications such as ASME U/U2, PED, and API 6A. It is equipped with a German SMS forging line and an American Niton spectrometer, achieving full traceability from raw materials to finished products. In the future, Longquan will continue to invest in the research and development of duplex steel materials, promoting the upgrading of flanges towards higher strength, lighter weight and greater intelligence.If necessary, please contact us for details or to discuss cooperation.