Stainless Bar｜Rust-Resistant, Easy to Machine, Strong – Ready for All Industries

Key Industry ChallengesIn industries such as mold making, machinery, automotive, food, and medical sectors, manufacturers frequently face issues like rust formation on stainless bars, cracking during machining, and dimensional or straightness deviations. Standard steel typically does not withstand corrosion in humid or chemical environments, leading to surface deformation, reduced hardness, and shorter service life. These problems directly affect part quality, production accuracy, and overall factory costs.

Root Cause of the Problem

Carbon steel lacks essential alloying elements like chromium and nickel, which form a protective anti-rust film. Additionally, its microstructure is unsuitable for applications requiring smooth surfaces, tight tolerances, and precision machining. This often results in tool wear, workpiece warping, and dimensional inaccuracies after machining.

Solution

Yamaichi Special Steel (Thailand) offers high-quality Japanese stainless bars, cold drawn and precision centerless ground to ensure high dimensional accuracy, excellent mechanical strength, easy machinability, and superior corrosion resistance. Every batch is tested under ISO 9001:2015 and JIS G4303 standards to guarantee consistent, reliable quality.

Specifications of YAMAICHI Stainless Bar

1. SUS303 — Free Cutting Stainless (Best for Machining)

• Austenitic structure (Cr-Ni 18-8)
• Sulfur added for easier machining and smooth finish
• Hardness: HV 180–230
• Corrosion-resistant in general environments
• Ideal for: Nuts, shafts, bushings, and general machine parts

2. SUS304 — General Purpose Stainless (Industry Standard)

• Austenitic structure (Cr18-Ni8)
• Excellent corrosion resistance
• Tensile strength: approx. 520–750 MPa
• Suitable for: Machine structures, general molds, electrical equipment
• Easy to polish and weld

3. SUS316 — Chemical Resistant Stainless

• Molybdenum (Mo) added for acid and chloride resistance
• Ideal for: Food, chemical, medical industries, and outdoor use
• Hardness: HV 150–200
• Higher corrosion resistance than SUS304

4. SUS403 — Martensitic Stainless (Hardenable Grade)

• 12% Chromium, suitable for quenching and tempering
• Post-treatment hardness: HRC 40–45
• Ideal for: Valve shafts, mechanical parts, and high-load molds

5. SUS430 — Ferritic Stainless (Magnetic)

• Nickel-free
• Moderate rust resistance
• Cost-effective, suitable for: Electrical appliances, decoration, general structures

6. SUS416 — Free Machining Martensitic Stainless

• Sulfur added (S) for improved machinability
• Hardenable to ~HRC 35–40
• Ideal for: Small machined parts, nuts, rotating shafts, or fasteners

7. KM31 / KM35F / KM38 — Special Machining Bar (Japan Grade)

• Premium Japanese grades, comparable to SUS303 / 416 / 420 Series
• Fine-grain structure, excellent machinability and surface finish
• Straightness tolerance: ±0.1 mm, Surface Roughness: Ra ≤ 0.3 µm
• Ideal for: CNC machining, molds, and precision parts

Key Advantages of Yamaichi Stainless Bars

• Manufactured to Japan Quality Standards and ISO 9001:2015
• Available in all structures: Austenitic / Martensitic / Ferritic / Free Cutting
• Centerless ground finish – ready for immediate use
• Standard sizes: 3–100 mm diameter
• Custom cut-to-length service
• Each batch inspected for straightness, hardness, and surface finish

※ For more information, please contact us or download the brochure.

Glossary

• Austenitic Stainless – Non-magnetic stainless steel with high toughness and corrosion resistance
• Centerless Grinding – A precision grinding method for round bars to ensure consistent diameter and straightness
• Free Cutting – Stainless steel formulated for easier machining, typically with added sulfur
• Martensitic Stainless – Hardenable stainless steel suitable for high-stress and wear-resistant applications

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