Duplex Stainless Steel (DSS) consists of two phases of ferrite and austenite in a volume ratio close to 1:1. Generally, the content of less phase also requires a minimum of 30% stainless steel. Duplex stainless steel has excellent mechanical properties and resistance to chloride stress corrosion, and is increasingly used in oil and gas pipelines, chemical transportation tanks and shipbuilding industries. As a nickel resource-saving stainless steel, duplex stainless steel can replace austenitic stainless steel in many cases, which can effectively reduce costs. After continuous upgrading and upgrading of products, Tientai Duplex Stainless Steel Flux Cored Wire TFW-2209 has become more and more perfect, reaching the advanced level at home and abroad. Let's take a look at the excellent performance of this product used in chemical tankers!
chemical element
In the case of low-carbon stainless steel, the content of Cr is 18~28% and the content of Ni is 3~10%. Some steels also contain alloying elements such as Mo, Cu, Nb, Ti, and N. Our TFW-2209 products meet the requirements of AWS A5.22 E2209T1-1/-4: C content is less than 0.04%, Cr content is close to 24.0%, 9% Ni and 3% Mo, and trace amounts The elements Cu, Ti, V and about 0.1% of the N element. The chromium content in the weld is Cr≥12%, which will form a very thin, but dense oxide film (known as passivation film) on the surface of the steel. The protective substrate will no longer be oxidized or corroded, and the stainless steel will not rust. The main reason is therefore excellent corrosion resistance. The nickel element contained can strengthen the ferrite and effectively increase the strength. Nickel reduces the low temperature brittle transition temperature of the weld, which gives the product a good low temperature impact toughness. The addition of nickel is not only resistant to acids, but also resistant to alkali and resistant to the atmosphere and salt. The addition of molybdenum prevents temper brittleness and increases corrosion resistance in certain media. Vanadium has a strong affinity with carbon, ammonia and oxygen to form a corresponding stable compound. Its main role is to refine the structure and grains. Titanium is used to fix carbon to eliminate the depletion of chromium at the grain boundaries, thereby eliminating or reducing the tendency to intergranular corrosion. Nitrogen is partially soluble in iron and has solid solution strengthening. Since the nitride precipitates on the grain boundary, precipitation strengthening occurs. Combined with other elements, it has precipitation hardening effect. In addition, nitrogen is also a strong ferrite forming element.
Welding operation
Tientai Duplex Stainless Steel Flux Cored Wire TFW-2209 uses 100% CO2 or 80% Ar+20% CO2. It can weld flat welding, fillet welding, horizontal welding, overhead welding and vertical welding. Welding current Wide application range, good workability, small splash, easy slag removal, no residue. The following is a photo of the vertical welding. After welding, the welding slag will fall off automatically. Give our welders a compliment!
