403 stainless steel plate remains a cost-effective, high-hardness martensitic grade in 2025. While its corrosion resistance is moderate, it offers significant wear strength and thermal stability suitable for industrial tools, turbines, and high-stress components. Prices vary by region, with factory-direct Chinese suppliers offering the most competitive rates.

We open with 403 stainless steel as a versatile, 12 % chromium martensitic alloy prized for high hardness, strength, and moderate corrosion resistance. It's widely applied in turbine blades, valve parts, and other demanding industrial contexts. Its affordability and mechanical performance sustain steady global demand.

Material Characteristics Overview

We note 403 is martensitic stainless steel (UNS S40300) with ~11.5–13 % Cr, low carbon (~0.15 %), and minor Ni, Mn, Si, P, S. The chromium provides corrosion resistance; carbon boosts hardness.

Chemical Composition & Physical Traits

We examine composition ranges: Cr 12–14 %, Ni ~0.5–1 %, C 0.15–0.40 %, Mn ≤1 %, Si ≤1 %, P ≤0.04 %, S ≤0.03 %. Its density (~7.75 g/cm³), melting point (1400–1450 °C), thermal conductivity (~25 W/m·K), and other thermal properties highlight its engineering suitability.

Mechanical Properties & Heat Treatment

We report tensile strength (520–700 MPa), yield strength (280–450 MPa), elongation (20–30 %) and hardness (~30–40 HRC) in annealed state. These metrics make 403 robust in high-stress applications. Heat treatments (annealing at 800–900 °C; hardening at 1000–1100 °C with oil or air quench) enable tailoring hardness and toughness.

Corrosion and Heat Resistance Profile

We clarify that 403’s corrosion resistance is moderate—adequate in mildly corrosive environments but inferior to grades like 304/316. It is prone to pitting in chloride-rich media. It tolerates continuous use up to ~600 °C, intermittent to ~650 °C, with scaling beginning around 700 °C (≈1300 °F).

Manufacturing Standards & Equivalents

We highlight common standards: UNS S40300, AISI 403, SUS403 (Japan), and EN 1.4006. Metric equivalents vary slightly but offer similar performance envelopes.

Processing: Fabrication, Machining & Welding

We emphasize that 403 is moderately machinable (~60 % relative to standard steel) and demands sharp tooling at moderate speeds. Weldability is workable but requires preheating and often post-weld heat treatment to prevent cracking. Cold and hot forming are feasible but limited by work hardening—bend radii must be controlled.

Applications & Industries

We list key uses:

• Aerospace: Turbine components (strength at elevated temperatures)

• Automotive: Exhaust valves (heat and wear resistance)

• Oil & Gas: Pump shafts (wear durability)

• General tools: Cutting implements, bearings, valves (wear and hardness focus)

• Additional: Food-processing machinery, chemical equipment, medical apparatus, structural and shipbuilding parts.

Price Landscape 2025: Global Comparison

We aggregated price data from suppliers:

*Note: Western prices are estimated based on typical mark-ups and may vary.

We observe that Chinese direct suppliers offer the most attractive pricing, particularly for bulk or OEM procurement.

Comparison with Alternative Grades

We contrast 403 with more corrosion-resistant grades like 304/316 (austenitic) and ferritic grades.

• 304/316: Superior corrosion resistance, better weldability, but lower strength and higher cost.

• Ferritic steels: Magnetic, cost-effective, but less hardenable and generally lower strength at high temperatures.

• 403 balance: Strength, affordability, moderate corrosion resistance—optimal for robust yet budget-sensitive applications.

FAQs

Q1: How does 403 stainless steel price compare to 304 or 316?
A: 403 generally costs less due to lower nickel content and simpler processing; 304/316 grades are more expensive given their superior corrosion resistance.

Q2: Can 403 be used in marine environments?
A: Only in limited, non-static marine contexts—its moderate chloride resistance makes it vulnerable in aggressive saltwater unless properly coated or polished.

Q3: What surface finishes are available for 403 plates?
A: Suppliers offer finishes such as BA, 2B, NO.1, NO.4, 4K, HL, 8K, mirror polishing, brushed—suited for appearance or performance requirements.

Q4: Is 403 stainless steel food-safe?
A: Yes—with proper polishing or BA finish, 403 can be used in food-processing equipment, offering adequate cleanability.

Q5: What is scaling temperature and why does it matter?
A: Scaling temperature (~1300 °F / 700 °C) is where oxidation accelerates. Above this, protective oxide layers break down—critical for high-temp use limits.