430F stainless steel round bar is a ferritic, free-machining stainless alloy (≈16–18% Cr) specifically modified with added sulfur/selenium to give excellent turning and automatic-screw-machine performance while retaining the basic corrosion resistance and magnetic properties of 430. For machined hardware, fasteners, trim, and medium-duty corrosion environments where cost and machinability matter more than high nickel content or high chloride resistance, 430F round bar offers the best value.

What is 430F stainless steel?

430F (often written AISI 430F or SUS430F) is a ferritic stainless steel derived from AISI/UNS 430 with controlled sulfur (and sometimes selenium) added to produce a free-cutting (free-machining) variant. The base is a straight-chromium alloy — typically ~16–18% chromium — which gives corrosion resistance characteristic of ferritic stainless steels. The “F” denotes free-machining: the added sulfur forms manganese sulfide inclusions that act as chip breakers and lubricants at the cutting zone, reducing tool wear and improving surface finish in automatic lathes and screw machines. Because of that sulfur, 430F is more readily machined but has slightly lower formability and slightly reduced corrosion resistance compared with plain 430.

Chemical composition

Below is a practical, industry-used composition table that assemblers, buyers and engineers reference for procurement and specifications. Values are shown as typical maximums or ranges — always confirm with mill test certificates (MTC) from your supplier.

Notes: sulfur content separates 430F from 430 (which is low in S). The S level is controlled to balance machinability with acceptable corrosion/ductility. Always request the exact MTC values for critical parts.

Mechanical & physical properties

Below are representative mechanical and physical properties used by design engineers for selection and initial calculations. For final design, use vendor MTC/tested values.

Practical remark: the mechanical numbers above are starting points. Because 430F is often used for turned parts that are subsequently cold-worked or polished, final part properties depend on the chosen fabrication path.

Applicable standards and specifications

Common standards/specifications that reference 430F (or the free-cutting variant of 430) include:

• ASTM / ASME: A276 (bars), A479 (for certain stainless bar/tube), A582 (cold-finished bars), A314 etc. — 430F variants are typically supplied to ASTM A276/A582 formats for round bar and bright bar.

• UNS / AISI: UNS S43020 (commonly used notation for 430F).

• JIS / SUS: JIS SUS430F is often used for Japanese-standardized product lines.

• EN / DIN: EN designations like X6Cr17 (430 family) and similar local descriptors exist; check supplier certs for exact EN numbers.

When ordering round bar for precision machining, specify: grade (430F / UNS S43020), standard (ASTM A276 / A582), diameter tolerance, surface finish (bright/turned), length, and required certifications (MTC, mechanical test reports, PMI if required).

Machinability, forming, welding, heat-treatment and finish

Machinability: 430F’s hallmark. The sulfur (or in some mills selenium) creates continuous micro-inclusions that break chips into short curls and provide lubricity at the cutting edge. This lowers cutting forces and extends tool life — ideal for high-speed screw machines, Swiss-type lathes and CNC turning centers. Expect significantly higher feed rates and surface finish quality versus plain 430.

Forming: Because of the added sulfur, 430F is less ductile than plain 430 and forms less predictably in severe stamping or deep drawing. For moderate bending and light forming it remains acceptable but avoid tight radii and stretch forming without trials.

Welding: Welding 430F is feasible using typical ferritic stainless welding consumables, but the free-machining inclusions can lead to embrittlement or porosity if not controlled. For welded components, many fabricators prefer regular 430 or a low-S variant. Post-weld annealing is not used to harden ferritics; consider design alternatives if heavy welding is necessary.

Heat treatment: Ferritic grades are not hardenable by heat treatment (no hardening by quench/temper). Properties are set by composition and cold work. Maximum safe scaling temperature and other high-temperature characteristics are available from supplier datasheets (Carpenter and others provide Tmax values).

Surface finishing: 430F is commonly supplied as bright bar or turned finish for immediate machining. Post-machining finishing methods include polishing, passivation and electropolishing if enhanced corrosion resistance or aesthetics are needed.

430 vs 430F: the precise technical difference

• Core composition: both share essentially the same chromium content (~16–18%) and low nickel content. The distinguishing chemical change is a controlled increase in sulfur/se-lines in 430F to improve chip breaking.

• Machinability: 430F is much easier to machine than 430; pick 430F when part geometry and production volume demand short chips and long tool life.

• Formability & corrosion: 430 (low S) is better for forming (deep drawing, bending) and has slightly superior corrosion resistance in aggressive environments. 430F trades a bit of those properties for machinability.

• Welding: plain 430 is generally preferred when welding is critical; 430F can be welded but may need special precautions.

Selection rule-of-thumb: use 430F for turned, machined components (fasteners, screws, shafts, connectors). Use 430 for stamped, formed or welded components where corrosion and forming are critical.

Typical uses for 430F stainless steel round bar

430F round bar is chosen where high machining throughput and economy are required along with moderate corrosion resistance:

• Precision machined fasteners, screws and threaded components.

• Small valve parts, shafts, bushings and stepped turned components.

• Automotive trim and interior parts where magnetism and finish are acceptable.

• Appliance components, brackets and trim where nickel-bearing stainless steels are unnecessary.

• Heat-exchange components where ferritic thermal conductivity is advantageous but corrosion is moderate.

Limitations: Not recommended for seawater or chloride-rich environments, nor where high ductility/forming or critical weld integrity is required.

430F stainless steel round bar — size & weight table

Engineers and buyers often need quick weight estimates to calculate material cost or to plan machining yields. The table below provides approximate weight per meter for common round bar diameters using density ≈ 7.75 g/cm³.

(Formula: area = π·(d/2)²; weight/m = area (cm²) × 7.75 g/cm³ × 100 cm/m → convert to kg.) For precise procurement and shipping calculations, use vendor weight tables or an online round-bar weight calculator.

Global price comparison 2025

Important note on prices: stainless steel prices vary continually (coil vs bar, mill vs distributor, MOQ, finish, and surcharges). Below is a snapshot approximation for 2025 using third-party price services and marketplace listings; treat these as indicative ranges and always request quotations (FOB or CIF) for firm buys. Sources include MEPS, MetalMiner and China wholesale platforms.

How to interpret these numbers:

• Coil indices are useful leading indicators; finished bright bars carry markups for drawing/cold finishing and straightening.

• China export quotes on large B2B platforms sometimes show very low FOBs (e.g., < USD 1,000/t) for commodity 430 coil — these typically reflect limited-spec lots or promotional pricing; major mill prices are higher. Always confirm MOQ, delivery lead time, inspection and MTC.

• For small orders of turned bright bar, per-kg cost will be higher due to processing and cutting charges.

What is equivalent to 430f stainless steel?

Note: Equivalence charts are approximate. When substituting across standards, check critical elements (e.g., sulfur level, carbon control) and confirm with the supplier.

Sourcing 430F round bar from China

As a multinational buyer, you need a supplier that combines consistent chemistry, mill certifications and reliable logistics. MWAlloys (our company) supplies 430F stainless steel round bar with the following strengths:

• Factory direct (100% mill origin): we supply at competitive factory pricing (no middleman markup) on standard and custom diameters.

• Stock & quick delivery: warehouse stock for common diameters and bright finishes; we offer expedited shipments for urgent production demands.

• Quality paperwork: full MTCs, chemical & mechanical test reports, and third-party inspection on request.

• Customization: lengths, chamfers, turned/bright finishes and cut-to-size services.

• Global shipping & compliance: FOB/CIF options to major hubs; export experience and support with documentation.

Procurement checklist for ordering 430F round bar from China (recommended):

1. Confirm grade (430F / UNS S43020) and acceptable sulfur range.

2. Specify standard (e.g., ASTM A276 / A582), diameter, tolerance and finish (turned bright or cold-drawn).

3. Request MTC (EN 10204/3.1 or 2.2 as needed).

4. Clarify MOQ, lead time, packaging and inspection rights (third-party inspection if required).

5. Check delivery terms (FOB, EXW, CIF) and shipping timeline.

Frequently asked questions

1. Is 430F stainless steel magnetic?
   Yes, it is ferritic and magnetic.

2. Can I weld 430F parts?
   Yes, but with caution: the free-machining inclusions can affect weld quality; for welded assemblies plain 430 or a low-S alternative is often chosen.

3. Is 430F suitable for seawater?
   No, 430F is not recommended for long-term exposure to seawater or chloride-rich environments. Use higher-alloy corrosion steels (e.g., 316L) for marine service.

4. What finishes are common for round bar?
   Bright turned (cold-finished), ground and polished finishes. For decorative or corrosion-sensitive parts, additional polishing or passivation is advised.

5. Which is better for machining: 430 or 430F?
   430F — intentionally free-machining; choose it for high-volume CNC or automatic turning.

6. How to specify a 430F bar order?
   Specify grade (430F / UNS S43020), standard (ASTM A276/A582), diameter tolerances, surface finish, length, MTC and packaging.

7. Are there food-contact concerns?
   For food contact, corrosion resistance and passivation quality matter; 430F is used in some food equipment, but regulatory/cleaning regimes must be verified. Ask for supplier’s hygiene/food-grade declarations.

8. Can 430F be hardened?
   Ferritic grades like 430F are not hardenable by heat treatment; strength is modified by cold work.

9. What tooling improvements help machining 430F?
   Carbide inserts with positive rake, appropriate coolant, higher feed rates and chip breakers are effective due to the short chips produced by the sulfur.

10. Typical delivery times from China?
    Depends on stock and finish; standard bright bars often ship in days to a few weeks if stock is available; customized draws or large orders may require longer lead times. MWAlloys maintains stock for common sizes to shorten lead times.