S31803  is nitrogen-balanced duplex stainless steel bright bar with roughly 50% ferrite + 50% austenite.
Nitrogen solid-solution hardening delivers yield strength ≥450MPa, double that of 316L. It combines ferrite’s outstanding chloride stress corrosion cracking (SCC) resistance and austenite’s high low-temperature toughness. High Cr-Mo-N passivation film provides superior pitting & crevice corrosion resistance versus 316L, 317L and S31500. Ultra-low carbon eliminates intergranular corrosion after welding.

Chemical element content (%)

Specification：1.00~300.00mm

Application: It is mainly used to manufacture replacement shafts for legacy seawater desalination equipment, H₂S-containing pump shafts for offshore oil & gas, FGD heat exchanger mandrels for power plants, pulp bleaching valve spools, marine circulating seawater pipe flanges, coastal high-salt wastewater treatment bolts, NACE sour oil & gas wellhead fasteners, low-temperature desulfurization valve bodies for waste incineration, stressed bars for chemical brine reactors, medium-corrosion standard parts for hydrometallurgy, etc.
Widely applied in legacy seawater desalination renovation projects, offshore oil & gas extraction platforms, complete power plant flue gas desulfurization systems, paper bleaching production lines, marine seawater cooling supporting facilities, high-salt wastewater environmental equipment, oil & gas sulfur-containing pipelines, hydrometallurgy anti-corrosion equipment and other industries.

Core Advantages Over Competitors

1. High quality stability: Full closed-loop production & dual online spectral/metallographic inspection strictly control C, Cr, Ni, Mo, N with ferrite-austenite ratio stabilized 40~60%. Uniform dispersed Mo-N precipitates ensure minor batch fluctuation of yield strength, SCC and pitting resistance for consistent mass production of legacy replacement and sour oil & gas components.

2. Excellent surface quality: Dedicated high-precision cold drawing & centerless grinding lines produce bars free of scale, scratches and pits with smooth uniform finish. Smooth surface reduces chloride-induced stress concentration to extend fatigue life under seawater & desulfurization cyclic service; secondary polishing is unnecessary for most precision machining.

3. Ultra-high dimensional accuracy: Precision cold rolling mills & automatic online detectors narrow tolerance range with tiny single-bar error and strong batch uniformity, unifying part sizes in automatic mass production to raise finished yield.

4. Rich product variety: According to market demand and customer's special requirements, customized products are provided to meet the use requirements under various complex working conditions, providing customers with more choices.

5. Perfect after-sales service: The perfect after-sales service system can respond to customer needs and feedback in a timely manner. For problems encountered by customers during use, technical support and solutions are provided to customers quickly.

We mainly engage in cold heading wire, bar, peeled bar, and profiled bar; our products cover 11 series and more than 300 grades, and we continue to develop a variety of professional steels. We can provide all-round solutions such as cold heading finishing line manufacturing and high-precision bright bar customization, and provide one-stop procurement services and package procurement solutions for global customers. The website displays some grades. If you don’t have the grade you need, please contact us by phone or email.