What Is Duplex Stainless Steel Pipe

What Is Duplex Stainless Steel Pipe

Duplex stainless steel tube has good welding performance. Compared with ferritic stainless steel and austenitic stainless steel, it does not have the welding heat affected zone of ferritic stainless steel. Due to the severe coarsening of the grains, the plasticity and toughness are greatly reduced. It is also not as sensitive to welding hot cracks as austenitic stainless steel.

Due to its special advantages, duplex stainless is widely used in petrochemical equipment, seawater and wastewater treatment equipment, oil and gas pipelines, papermaking machinery and other industrial fields. In recent years, it has also been studied in the field of bridge load-bearing structures and has good performance Prospects. Duplex ss pipe has a solid-quenched structure in which the ferrite phase and the austenite phase account for half each. Generally, the minimum phase content may reach 30%.

The main characteristic of duplex stainless steel is that its yield strength can reach 400-550mpa, which is twice that of ordinary stainless steel, so it can save materials and reduce equipment manufacturing cost. In the aspect of corrosion resistance, especially in the condition of bad medium environment (such as seawater, high chloride ion content), the pitting corrosion resistance, crevice corrosion resistance, stress corrosion resistance and corrosion fatigue performance of duplex stainless steel are obviously superior to that of ordinary austenitic stainless steel, which can be compared with high alloy austenitic stainless steel.

When selecting duplex stainless steel in different corrosive environments, it should be noted that the corrosion resistance of steel is always relative. Although stainless steel duplex has better local corrosion resistance, for a certain duplex stainless steel, it also has An applicable range of medium conditions, including temperature, pressure, medium concentration, pH value, etc., needs to be carefully selected. Many of the data obtained from literature and manuals are laboratory corrosion test results, which are often different from the actual conditions of the project. Therefore, you need to pay attention when selecting materials. If necessary, you need to conduct corrosion tests in actual media or under on-site conditions. Coupon testing and even testing of simulated devices.