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Published: November 7, 2025 | Updated: November 7, 2025By Gangsteel Engineering Team – 25+ Years in Stainless Steel Export Excellence
When it comes to crafting durable bars for the unforgiving demands of industrial machinery, few materials deliver the punch of A479 UNS S41500. This martensitic stainless steel bar grade, specified under ASTM A479 for seamless and hot-worked bars and shapes, has been a cornerstone of Gangsteel's production line for over two decades.
As a trusted Chinese exporter serving petrochemical plants, offshore rigs, and heavy equipment fabricators worldwide, we've turned countless billets of S41500 into precision bars that power everything from drill stems to compressor rods. If you're battling corrosion in sour environments or chasing higher yield without ballooning costs, this strength guide arms you with the facts, figures, and field-tested wisdom to spec it right.
Picture this: a 2024 deepwater drilling operation off Brazil's coast, where our A479 S41500 bars formed the backbone of stabilizer shafts enduring 2,000 rpm spins in 30% chloride brine. Not a single fatigue crack after 6 months— that's the real-world grit of this alloy. Often equated to F6NM in forging parlance, UNS S41500 bars blend 12-14% chromium for passivation with nickel and molybdenum for enhanced toughness, all while keeping machinability sharp. In this no-fluff breakdown, we'll dissect its strength profile, from chemical roots to mechanical might, plus sourcing savvy. Backed by our ISO-certified testing labs and 500+ client audits, consider this your blueprint for bars that last.
ASTM A479 UNS S41500 bars are engineered for high-stress roles where moderate corrosion resistance meets superior mechanical fortitude. This spec governs austenitic, ferritic, and martensitic stainless bars for elevated-temp or corrosive service, with S41500 excelling in the martensitic camp thanks to its quench-and-temper response. Bars come in rounds, squares, hexes, or custom profiles, hot-rolled or annealed for starting conditions that forge well under load.
At Gangsteel, we stock S41500 bars from 10mm to 500mm diameter, drawn from vacuum-remelted ingots to slash inclusions. Its density hovers at 7.85 g/cm³, making it weight-efficient for long shafts, while a PREN of ~19 shrugs off pitting better than plain 410. We've machined these bars into API 6A-compliant stems that outlasted duplex alternatives in H2S tests by 50%—proof that strength isn't just numbers; it's engineered reliability. For complementary flat stock, pair with UNS stainless steel plates in the same grade.
The chemistry of A479 UNS S41500 bars is dialed in for balance: low carbon to curb brittleness, ample Cr for oxide films, and alloying elements to tune hardenability. Gangsteel melts to these tolerances using AOD (Argon Oxygen Decarburization) for ultra-clean results, with every heat PMI-verified.
|
Element |
% Range (ASTM A479) |
Gangsteel Typical |
Role in Bar Strength |
|---|---|---|---|
|
Carbon (C) |
0.05 max |
0.02-0.04 |
Suppresses martensite over-hardening; enables fine carbide dispersion for uniform strength. |
|
Manganese (Mn) |
0.50-1.00 |
0.60-0.80 |
Boosts deoxidation and toughness; stabilizes austenite during hot-rolling. |
|
Silicon (Si) |
0.60 max |
0.30-0.50 |
Improves scale resistance in forging; minimal to avoid embrittlement. |
|
Phosphorus (P) |
0.030 max |
<0.015 |
Controlled for weld-free zones; low P enhances transverse ductility in bars. |
|
Sulfur (S) |
0.030 max |
<0.010 |
Trace for free-machining; balanced to prevent hot-shortness in extrusion. |
|
Chromium (Cr) |
11.50-14.00 |
12.50-13.20 |
Core for corrosion barrier; elevates yield by pinning dislocations. |
|
Molybdenum (Mo) |
0.50-1.00 |
0.60-0.80 |
Enhances secondary hardening; critical for sour service creep resistance. |
|
Nickel (Ni) |
3.50-5.50 |
4.20-4.80 |
Refines martensite laths; improves low-temp impact without softening. |
|
Nitrogen (N) |
0.10 max |
<0.05 |
Interstitial strengthener; limited to curb strain aging in bars. |
|
Iron (Fe) |
Balance |
>82.00 |
Matrix alloy—our VIM process yields 99.8% purity for fatigue superiority. |
These specs ensure A479 compliance, with Gangsteel offering low-residual variants for premium apps. Mill certs trace back to the ladle, giving you audit-ready assurance.
Post-solution anneal (1010-1120°C) and temper (565-760°C), A479 UNS S41500 bars unleash martensitic muscle. Tests per ASTM A479 (longitudinal specimens) reveal:
|
Property |
Min Value (Annealed + Tempered) |
Typical Gangsteel Bar |
Bar-Specific Insights |
|---|---|---|---|
|
Tensile Strength (MPa) |
795 |
850-920 |
Anchors high-load apps; we've pulled 950 MPa in 100mm dia. rounds. |
|
Yield Strength (0.2% Offset, MPa) |
620 |
680-750 |
Exceeds for safety margins; vital for torque-loaded shafts. |
|
Elongation (%) |
15 (in 50mm) |
18-22 |
Measures forge ductility; higher in peeled bars for turning. |
|
Hardness (HRB) |
32 max |
25-30 |
Soft for machining; tempers to HRC 22-28 for wear resistance. |
|
Reduction of Area (%) |
40 |
45-55 |
Gauges necking resistance; key for upset ends in fittings. |
|
Charpy V-Notch Impact (J) |
27 @ -18°C |
32-40 @ -46°C |
Absorbs shocks in impacts; NACE-optimized for no transition drop. |
Service at 350°C sees <8% tensile loss; down to -196°C, yield climbs 10%. Gangsteel's tensile machines (calibrated to ASTM E8) and impact testers routinely validate these, with data showing bars outperforming castings by 25% in cyclic bending.
Bars arrive annealed, but unlock full strength with: austenitize 1050°C, air-quench, temper 620°C/2hrs. This yields tempered martensite with delta-ferrite islands for balanced props. Machining? Feeds/speeds like 4140: carbide tools at 100 m/min, coolant mandatory to dodge built-up edge. Pitfall: Skip PWHT on welds, and sigma embrittles— we've stress-relieved 200mm bars at 650°C without distortion.
For standards integration, A479 bars mesh with ASTM A240 /A240M sheets in assemblies.
These bars fortify sour gas valves (API 6A), pump plungers in refineries, and propeller shafts in tugs. In renewables, they're spindles for tidal turbines, resisting biofouling.
Gangsteel case: 2025, a Norwegian subsea tie-back used 8 tons of 150mm S41500 bars for riser connectors—endured 500 bar/5,000 cycles, per DNV tests. Or a U.S. fracking firm's 50mm hex bars in manifolds: cut failures 35% vs. 17-4PH, saving $200K annually.
November 2025 pricing for A479 S41500 bars: $2,600-2,800 USD per ton FOB Tianjin, steady amid stable alloys. Rounds: $2,600 base; peeled +$150/ton.
Gangsteel perks: Peel-and-ship service, 98% on-time. Explore UNS S41500 stainless steel plate for bar-sheet kits.
Q: What defines the strength of A479 UNS S41500 bars?
A: Min tensile 795 MPa, yield 620 MPa, 15% elongation, HRB 32 max. These ensure robust performance in loads up to 1000 MPa; Gangsteel's bars average 880 MPa tensile for extra margin in UNS S41500 stainless steel plate hybrids.
Q: How does A479 UNS S41500 compare to AISI 4140 bars?
A: S41500 yields 620 MPa vs. 4140's 415, plus Cr corrosion edge—PREN 19. Forges similarly but welds easier. Swapped in a 2024 gearbox, boosting life 50% in wet conditions.
Q: What's the current price for A479 UNS S41500 bars?
A: $2,600-2,800/ton FOB; discounts to $2,500 for 5+ tons. Q4 stable; our direct forging saves 20% vs. imports—quotes include size-specific calcs.
Q: Are A479 UNS S41500 bars NACE-compliant for sour service?
A: Yes—MR0175/ISO 15156 at <22 HRC, HIC-resistant. Yield 620 MPa handles 20% H2S/150°C. Supplied 15 tons to Exxon; aced 500-hr autoclave tests.
Q: What's the ideal heat treatment for A479 S41500 bars?
A: Anneal 1010°C, quench air, temper 620°C/2hrs for HRC 25-28. Elongation hits 18%; avoid 425-540°C. Our HT logs show 99% uniformity in 300mm bars.
Q: What equivalents exist for A479 UNS S41500 bars?
A: EN 1.4313 (bars), ASME SA479 (pressure). 1.4313 for EU; SA479 for boilers. Dual-spec at Gangsteel—streamlined a UK client's recert by 40%.
Q: How do you guarantee bar quality under A479?
A: 100% UT (A479 S12), tensile per E8, chem per A479. ISO 9001 mills; 2025 zero defects. Links to ASTM A240 /A240M for full assemblies.
Q: Lead time and MOQ for custom A479 UNS S41500 bars?
A: MOQ 500 kg; stock 10 days, custom 25. Air options +$0.40/kg for urgency. Rushed 3 tons to Singapore in 8 days last month.
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