Processing technology of duplex stainless steel pipe

The Riser of offshore oil platform is washed by Wave for a long time, so it must have high strength and good resistance to pitting corrosion. The dual-phase stainless steel pipe has the advantages of high pitting corrosion resistance, good mechanical properties and chloride ion corrosion resistance, and is an ideal material for offshore oil platform riser, next to understand the processing technology of dual-phase stainless steel pipe bar! However, the duplex stainless steel pipe is very sensitive to the precipitation of the third phase, such as intermetallic compounds, so it is difficult to control the production process in welding and heat treatment. Describes the production process of perfect duplex stainless steel pipe. The priorities include testing raw materials, ultrasonic testing of stainless steel plates, planing, shaping, pre-welding, roundness, cutting, welding, sizing and heat treatment, welding line inspection, pipe end penetration inspection, water pressure test, pickling passivation and finished product inspection after packaging into storage. The second is forming, in the production of straight seam welded pipe, the production difficulty is to effectively give the stainless steel edge of the bending moment guarantee, the traditional forming technology is difficult to solve, but the yield strength of duplex stainless steel is about twice that of ordinary Austenitic stainless steel, and the forming difficulty is also increased.

The flexible forming technology makes use of the tension effect of the winding and bending, and applies the bending moment to the edge of the stainless steel strip to the maximum extent, the forming degree of bending edge can be adjusted freely to achieve the best welding condition. Welding, using a combination of Plasma arc welding and tungsten arc welding techniques. First, plasma arc welding is used as penetration welding, showing the effect of single-side welding, double-side forming; then, tungsten arc welding is carried out in the filling and cover, welding with pure argon protection. In order to reduce the tendency of harmful phase precipitation, it is better to use the lowest possible line energy, the best line energy is less than 16kJ/cm. The outer interlayer temperature is very important for the welding of duplex stainless steel. It must be controlled below 100. Too high interlayer temperature will increase the tendency of harmful phase precipitation and affect the product performance. Heat treatment. In the post-weld heat treatment, the induction furnace is used to carry out solid solution treatment on the whole welded pipe. Heat treatment temperature reaches 1050-1120, with water shower cooling to 40 or below. The existence of austenite in dual-phase structure can reduce the brittleness and grain growth tendency of high chromium ferrite, and improve the weldability and toughness, the yield strength, grain boundary corrosion resistance and stress corrosion resistance of austenite in stainless steel can be improved by chromium-rich ferrite, in particular, chlorides and sulfides have high stress corrosion cracking (SCC) ability, so they can effectively solve long-term problems. The above is the dual-phase stainless steel tube processing technology, if you need to know more stainless steel rectangular tube, stainless steel sanitary tube, stainless steel seamless tube content, you can contact us at any time!