321 Stainless Steel Round Bar

321 Stainless Steel Black Polished Round Bar is a high-performance alloy that combines the strength and durability of 321 stainless steel with a sleek, black polished finish. The black polished surface provides a unique aesthetic while retaining all the superior properties of 321 stainless steel, making it ideal for both functional and decorative applications. The addition of titanium in 321 Stainless Steel ensures exceptional resistance to oxidation, corrosion, and high-temperature environments, making it a perfect material for use in demanding industries like aerospace, chemical processing, and marine.

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Product Introduction

The 321 Black Polished Round Bar redefines industrial elegance, combining titanium-stabilized heat resistance with a mirror-grade black oxide finish. Engineered for applications demanding visual sophistication and extreme durability, it excels in luxury architectural frameworks, high-temperature décor, and precision instrumentation. Its seamless blend of dark luster and technical prowess resists both thermal scaling and environmental degradation.

Global Compliance & Surface Finish Standards

Region	Material Standard	Finish Specification
USA	ASTM A314	AMS 2700 (Electrochemical Polish)
Europe	EN 10088-2	DIN 50939 (Black Oxide Coating)
Japan	JIS G4303	SUS 321-BP (Class 4 Reflectivity)
International	ISO 9444	Ra ≤0.2μm (Post-Polish Roughness)

Material Innovation

Core Alloy Attributes

Titanium Stabilization: Ti ≥5×C% prevents intergranular corrosion, even after prolonged exposure to 800°C.

Black Oxide Layer: 3–5μm thickness via controlled electrochemical oxidation, enhancing scratch resistance and light absorption.

Enhanced Surface Properties

Gloss Level: 85–95 GU (Gloss Units) at 60° angle.

Adhesion Strength: 15 MPa (Per ASTM D3359 Crosshatch Test).

UV Stability: ΔE <1.5 after 1.000 hrs Xenon arc testing (ASTM G155).

Technical Superiority

Category	Performance	Benchmark
Corrosion Resistance	1.500 hrs neutral salt spray (ASTM B117)	10x better than normal coating
Thermal Cycling	500 cycles (200°C ↔ 800°C) without finish delamination
Load Capacity	600 MPa tensile strength (cold-drawn)
Hygienic Compliance	FDA 21 CFR 175.300 (Indirect food contact)

5 Market-Differentiating Features

Stealth-Grade Aesthetics

Matte-black finish minimizes glare in optical/laser systems while meeting MIL-STD-3009 low-reflectivity criteria.

Biofilm Resistance

Nano-textured surface inhibits bacterial adhesion (ISO 22196: >99% reduction vs. unpolished 321).

Zero Maintenance Appeal

Self-healing oxide layer regenerates in oxygen-rich environments, eliminating repainting needs.

Thermal-Emissivity Control

Black finish enhances radiative heat dissipation (ε=0.85 at 500°C per ASTM E903).

Circular Economy Ready

100% reclaimable via alkali stripping; achieves Cradle-to-Cradle Bronze certification.

Cross-Industry Applications

Sector	Innovative Use Cases
Luxury Architecture	Facade cladding, avant-garde sculptures
Semiconductor	Vacuum chamber components, black-body radiators
Automotive	High-end exhaust tips, heat-shielded trim
Consumer Tech	Wearable device frames, premium audio hardware
Energy	Solar absorber tubes, geothermal sensor housings