304 stainless steel square bar (AISI 304 / SUS304 / EN 1.4301) is the most versatile and widely used 18-8 austenitic stainless steel. Featuring balanced chromium and nickel composition, it delivers outstanding corrosion resistance, excellent ductility, superior weldability and reliable mechanical stability. Unlike high-strength spring-grade stainless steel, 304 square bar focuses on comprehensive performance, easy machining, forming and welding, making it the preferred structural stainless material for industrial manufacturing, architectural decoration, food machinery, chemical equipment and daily engineering projects.

Manufactured through professional hot rolling, cold drawing and precision finishing processes, the square bar features flat and smooth surface, precise right-angle dimension, uniform internal structure and stable tolerance. It supports cutting, bending, drilling, welding and other deep processing, meeting diverse customized structural and functional usage demands.

2. International Standard Grade Equivalents & Chemical Composition

2.1 Global Equivalent Grades (Full Cross-Reference)

304 stainless steel has unified equivalent grades in mainstream global standards, with minor compositional tolerance differences. The complete international grade matching table is as follows:

Grade Note: All above grades are fully interchangeable for general industrial and decorative use. The minor difference lies in carbon and chromium tolerance ranges, with no obvious difference in daily processing and service performance.

2.2 Chemical Composition (Standard: ASTM A276 / GB/T 1220 / EN 10088-3, wt%)

Core Advantage: Low carbon content effectively prevents intergranular corrosion after welding; standard 18Cr-8Ni alloy structure forms a dense self-healing oxide film on the surface, providing excellent rust and corrosion resistance in atmospheric, fresh water and mild corrosive working environments. Strict control of sulfur and phosphorus ensures smooth welding and no brittle fracture during cold bending processing.

3. Physical & Mechanical Properties

3.1 Basic Physical Properties (Room Temperature)

Density: 7.93 g/cm³
Melting Point: 1398–1454℃
Thermal Conductivity: 16.2 W/m·K
Specific Heat Capacity: 500 J/kg·K
Resistivity: 0.72 Ω·mm²/m
Linear Expansion Coefficient: 17.2×10⁻⁶ /℃ (20–200℃)
Elastic Modulus: 193 GPa
Shear Modulus: 72 GPa
Poisson’s Ratio: 0.24
Magnetism: Completely non-magnetic in annealed state; slightly magnetic after cold working

3.2 Key Mechanical Properties (Annealed State)

Performance Feature: Excellent toughness and plasticity, far better processing performance than high-carbon spring stainless steel; no cracking during cutting, bending, stamping and welding; stable mechanical structure, not easy to deform under long-term static load. Consistent mechanical property standards across global grades ensure uniform processing effect for cross-border orders.

4. Product Specifications & Surface Types

4.1 Size Range

Square Size: 3×3mm – 400×400mm (custom special sizes available)
Standard Length: 6000mm / fixed custom length
Dimension Tolerance: ±0.02mm ~ ±0.05mm (precision grade available)
Right Angle: Standard 90° flat right angle, no burrs

4.2 Common Surface Finishes

Black Hot Rolled Surface: Oxidized black skin, low cost, suitable for industrial structural parts and hidden engineering components
Pickled Matte Surface: Uniform silver-gray surface, no oxide layer, easy for subsequent processing and welding
Polished Bright Surface: Smooth mirror finish, anti-rust and aesthetic, ideal for decorative and exposed parts
BA Bright Surface: High-precision bright finish, clean and flawless, for high-end precision equipment

5. Core Key Features

●Superior Corrosion Resistance: Resists rust, oxidation and corrosion in humid air, fresh water, food-grade weak acid and alkali environments; excellent anti-rust performance for indoor and outdoor long-term use
●Excellent Processing Performance: Outstanding ductility and toughness, supports cutting, bending, drilling, tapping, welding and stamping without cracking
●Weldability & Machinability: Low carbon content avoids welding cracks and intergranular corrosion; stable structure for high-precision machining
●High & Low Temperature Resistance: Stable performance at -196℃ to 800℃, suitable for normal temperature, high-temperature and low-temperature working conditions
●Non-toxic & Sanitary: Food-grade compliant, no precipitation of harmful substances, safe for food and medical equipment applications
●Durable & Low Maintenance: Wear-resistant and aging-resistant, no need for surface coating, long service life and low later maintenance cost
●Cost-Effective: Balanced performance and price, more practical than 316 series, better corrosion resistance than 201 series, ideal universal structural stainless steel

6. Typical Applications & Grade Application Guidance

6.1 Food & Medical Industry

Food processing equipment, kitchen equipment frames, sanitary production line brackets
Medical instrument structural parts, pharmaceutical equipment supports, sanitary hardware accessories

6.2 Architectural & Decoration Engineering

Stair handrail frames, curtain wall supports, decorative structural square bars
Outdoor guardrails, landscape engineering brackets, building anti-corrosion structural parts

6.3 Mechanical & Industrial Manufacturing

Automation equipment frames, machinery support brackets, tooling fixture structural parts
Conveyor equipment parts, pump valve structural accessories, general mechanical anti-corrosion components

6.4 Chemical & Environmental Protection Industry

Low-pressure chemical equipment brackets, environmental protection sewage treatment equipment parts
Mild acid and alkali medium working structural parts, anti-corrosion pipeline accessories

6.5 Daily Hardware & Custom Processing

Hardware tool structural parts, equipment base supports, customized special-shaped mechanical parts
Furniture anti-corrosion brackets, precision machinery assembly parts

7. Grade Comparison (304 VS 304L VS 301 VS 201)

8. Production Standards & Certification

Compliant with global mainstream standards including ASTM A276, EN 10088-3, JIS G4303, GB/T 1220, GOST 5632; fully matches international equivalent grades. Support SGS, RoHS, food-grade inspection and customized factory test reports, completely meeting global export and engineering procurement standards.