431 is nickel-enhanced high-chromium martensitic stainless steel bright bar.

Two key benefits from nickel: ① Eliminates low-temperature brittle fracture by boosting impact toughness; ② Stabilizes chromium passivation film, delivering superior resistance to atmosphere, nitric acid and organic acid vs 410 & 420, the best balanced corrosion performance among standard martensitic grades.

Heat treatment system: Oil quenching at 1000~1050℃ + tempering 200~600℃ achieves tensile strength 850~1000MPa and hardness HRC30~45. Full annealing at 760~800℃ slow cooling softens material to HB ≤295 for easy machining.

Without molybdenum, poor performance in concentrated seawater and high-chloride wet media. Limitation: Long-term aging at 400~600℃ precipitates brittle M₂₃C₆ carbides; welding triggers intergranular rust, full re-quench-tempering required for pressure components.

Chemical element content (%)

Specification：1.00~300.00mm

Application:It is mainly used to manufacture high-strength aerospace fasteners, steam turbine blades, nitric & acetic acid chemical pump shafts, high-pressure anti-corrosion valve stems, medium-temperature chloride-free heat exchange bars for solar thermal power, low-pressure chloride-free marine pipe flanges, wear-resistant pins for food organic acid equipment, load-bearing medium-temperature tooling for heat treatment furnaces, short transmission shafts for power plant medium-temperature auxiliary machines, high-pressure hot steam circulation standard parts, etc.
Widely applied in aerospace supporting components, thermal power steam turbines, nitric & phosphoric chemical anti-corrosion equipment, solar thermal medium-temperature dry heat facilities, ocean-going marine chloride-free supporting parts, food acid drying lines, industrial heat treatment furnaces and medium-temperature thermal steam pipe networks.

Core Advantages Over Competitors

1. High quality stability: Full closed-loop production with dual online spectral & metallographic inspection strictly control C, Cr, Ni key alloy elements. Controllable martensitic grains and evenly dispersed carbide precipitates ensure negligible batch fluctuation of low-temperature toughness, nitric acid resistance and creep strength for consistent mass production of aerospace and chemical high-pressure components.

2. Excellent surface quality: Dedicated high-precision cold drawing & centerless grinding lines produce bars free of peeling, scale, scratches and pits with mirror finish. Smooth surface reduces cyclic thermal oxidation stress concentration to greatly extend fatigue life of parts operating long-term at 500℃ under steam & acid service; secondary polishing is unnecessary for most precision machining.

3. Ultra-high dimensional accuracy: Precision cold rolling mills and automatic online dimension detectors narrow tolerance range with tiny single-bar error and strong batch uniformity. Unified part specifications during automatic mass production significantly raise finished yield and machining precision.

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.