Project Description
440A (UNS S44002 / 1.4109 / X70CrMo15 / SUS440A / 70Х15М) is a high-carbon martensitic stainless steel bar delivering exceptional hardness after heat treatment while retaining useful corrosion resistance in mild environments. With approximately 17% chromium and a controlled molybdenum addition, 440A occupies the sweet spot between the lower-carbon 420 series and the maximum-hardness 440C — offering better machinability and toughness than 440C yet significantly higher attainable hardness than 410 or 420. SHUNFU METAL manufactures and exports this grade as a strategic product for the global petroleum equipment supply chain, operating under ISO 9001 and API Q1 certified quality systems with full lot traceability from melt to dispatch.
440A Stainless Steel — High-Hardness Martensitic Grade
440A belongs to the high-carbon martensitic stainless steel family — alloys that achieve their service properties through quenching from the austenitizing range to form hard martensite, followed by tempering to balance hardness with toughness. Carbon content of 0.60–0.75% enables through-hardening up to 57 HRC, approximately 6–8 HRC points above the maximum of 420 and comparable to many tool steels, while the 16–18% chromium content provides oxidation resistance and mild-environment corrosion protection. SHUNFU METAL refines each 440A heat through AOD processing, which delivers tight carbon and chromium control plus low sulfur for improved transverse properties. The ISO 9001 framework governs every stage: incoming raw material verification, spectrometric chemistry checks, heat treatment chart recording, mechanical test sampling per ASTM A370, and final dimensional inspection. When specified for API-governed applications, API Q1 supplementary requirements — including independent third-party witness testing and retained reference samples — are applied in full.
The practical advantage of 440A over 440C lies in its improved machinability in the annealed condition (typical machinability rating ~45% of B1112 versus ~30% for 440C), lower quench cracking risk in complex sections, and measurably higher toughness at equivalent hardness levels. SHUNFU METAL supplies 440A in the annealed condition for customer machining with subsequent in-house hardening, or fully heat-treated to target hardness per customer specification, supported by complete heat treatment records and mechanical test certificates.
Equivalent Grades of 440A Across International Standards
| Standard / Specification | Designation |
|---|---|
| ASTM A276 / A276M | Type 440A (UNS S44002) |
| ASTM A580 / A959 | 440A (S44002) Wire / Grade Reference |
| AMS 5631 | 440A (S44002) Bars & Forgings |
| EN 10088-3 | X70CrMo15 (1.4109) |
| DIN EN 10088-3 | X70CrMo15 (1.4109) |
| JIS G4303 | SUS 440A |
| GOST 5632 / GOST 5949 | 70Х15М (70X15M) |
| GB/T 1220 | 7Cr17Mo / 68Cr17 |
Oil & Gas Industry Applications
440A stainless steel bars serve across upstream, midstream, and downstream petroleum operations wherever high surface hardness, wear resistance, and moderate corrosion protection converge. The grade finds extensive use in valve internals, rotating-element bearings, pump wear components, and precision metering devices that must resist both mechanical abrasion and mildly corrosive process fluids. SHUNFU METAL supplies 440A bars to valve manufacturers, pump OEM shops, bearing houses, and machining workshops supporting the oil and gas industry globally, with ISO 9001 and API Q1 certification ensuring compliance with end-user quality and traceability requirements.
Valve Balls & Seats
Through-hardened ball-valve balls, seat rings, and sealing faces for API 6D and API 6A gate, ball, and plug valves.
Valve Stems & Trim
Hardened stems, discs, and internal trim for control, choke, and safety-relief valves in moderate-corrosion hydrocarbon service.
Ball & Roller Bearings
Hardened bearing races and rolling elements for downhole drilling motors, top drives, and rotating control devices.
Pump Wear Rings
Case and impeller wear rings for API 610 centrifugal pumps, resisting galling and abrasive wear in produced-water and light hydrocarbon duty.
Compressor Valve Plates
Hardened reciprocating compressor valve plates and springs for natural gas gathering and gas-lift compression service.
Throttle & Orifice Components
Hardened throttle bushings, orifice plates, and flow beans for chokes and pressure letdown stations.
Injector Nozzles
Hardened nozzles and needle valves for chemical injection quills and fuel-injection metering systems.
Check Valve Internals
Hardened poppets, discs, and guide bushings for swing and lift check valves in upstream gathering and midstream pipeline service.
High-Hardness Fasteners
Studs, set screws, and shear pins requiring surface hardness above 50 HRC for wear-dominated bolted joints in field equipment.
Supply Range of 440A Stainless Steel Bar
SHUNFU METAL manufactures and stocks 440A stainless steel in hot-rolled, forged, and cold-finished bar forms covering the dimensional spectrum required by valve, bearing, and pump component manufacturers. Production routes include hot rolling from continuous-cast bloom, open-die forging with upset reduction ratios ≥ 4:1 for structural integrity, and precision peeling or centerless grinding to IT 7–8 tolerances. Every lot undergoes ultrasonic inspection per ASTM E2375 / EN 10228-3, dimensional checks against order tolerances, and hardness testing (HRC or HB depending on condition). The ISO 9001 and API Q1 quality system ensures complete traceability: each bar is stamped with heat number and re-identified after cutting, with certificates linking product back to melt chemistry, heat treatment chart record, and mechanical test results.
| Product Form | Diameter / Section Range | Length | Surface / Condition |
|---|---|---|---|
| Hot-Rolled Round Bar | ⌀6 mm – ⌀300 mm | 3,000 – 6,000 mm | Annealed & Peeled / Cold Drawn |
| Forged Round Bar | ⌀80 mm – ⌀1,000 mm | 2,000 – 7,000 mm | Annealed / Rough Machined |
| Hot-Rolled Flat Bar | 3–60 mm thick × 15–400 mm wide | 3,000 – 6,000 mm | Black / Peeled / Ground |
| Forged Flat / Block | 30–400 mm thick × 150–1,200 mm wide | 1,000 – 4,500 mm | Annealed / Rough Machined |
| Cold-Finished / Ground Bar | ⌀3 mm – ⌀100 mm | 1,000 – 4,000 mm | Centerless Ground / Polished |
Bars supplied in the annealed condition (max 95 HRB / ~215 HB) for customer machining and in-house hardening, or fully heat-treated to target hardness per specification (49–57 HRC range). Non-standard diameters, stepped shafts, hollow bars, and cut-to-length pieces available on inquiry. PKO/PE coating, VCI wrapping, and sea-worthy timber crate packing standard for export shipments.
Chemical Composition of 440A (EN 10088-3 / ASTM A276)
The chemical composition of 440A is defined under European and North American standards with a notable difference: EN 10088-3 specifies a slightly broader carbon range (0.60–0.80%) and lower chromium (14.0–16.0%), while ASTM A276 tightens chromium to 16.0–18.0% with a narrower carbon band (0.60–0.75%). SHUNFU METAL controls each heat to the tighter overlap of both specifications through AOD refining, delivering carbon at 0.65–0.73% and chromium at 16.5–17.5% as standard. Spectrometric verification is performed on every cast and product analysis accompanies each certificate. The API Q1 system mandates retained reference samples for five years and independent third-party rechecks for all critical oil and gas orders.
| Element | EN 10088-3 X70CrMo15 (1.4109) | ASTM A276 Type 440A (S44002) |
|---|---|---|
| Carbon (C) | 0.60 – 0.80 | 0.60 – 0.75 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 | ≤ 0.040 |
| Sulfur (S) | ≤ 0.015 | ≤ 0.030 |
| Chromium (Cr) | 14.0 – 16.0 | 16.0 – 18.0 |
| Molybdenum (Mo) | 0.20 – 0.80 | ≤ 0.75 |
All values in weight percent (wt%). Cast analysis per respective standard. EN 10088-3 additionally restricts Ni ≤ 0.50%. SHUNFU METAL’s AOD practice typically achieves P ≤ 0.025% and S ≤ 0.010%, well inside both specification maxima. For bearing and valve applications requiring enhanced cleanliness, vacuum degassing and refining modifications are available.
Mechanical Properties — Annealed & Hardened Conditions
440A achieves its full mechanical performance through austenitizing at 1,010–1,065°C followed by oil or forced-air quenching to form hard martensite, then tempering at 150–370°C to adjust the hardness/toughness balance. Higher tempering temperatures within this range reduce hardness and residual stress but improve toughness; tempering between 370–540°C is avoided due to reduced corrosion resistance from chromium carbide precipitation. Annealed bars (heated to 845–900°C and slowly cooled) provide maximum machinability for customer processing before finish heat treatment. SHUNFU METAL executes all heat treatment in calibrated furnaces under ISO 9001 and API Q1 protocols with chart-recorder validation, ensuring uniform through-section properties. Stress relief, when requested, is performed at 28°C below the final tempering temperature.
| Condition | Tensile Rm (MPa) | Yield Rp0.2 (MPa) | Elong. A5 (%) | RA Z (%) | Hardness |
|---|---|---|---|---|---|
| +A Annealed (ASTM A276) | ≥ 725 | ≥ 415 | ≥ 20 | — | ≤ 95 HRB (~215 HB) |
| +QT315 Hardened & Temp. 315°C (ASTM A276) | ≥ 1,790 | ≥ 1,650 | ≥ 5 | ≥ 20 | ≥ 51 HRC |
| +QT200 Hardened & Temp. 150–200°C (Typical) | 1,820 – 2,050 | 1,700 – 1,950 | 3 – 5 | — | 54 – 57 HRC |
| +QT300 Hardened & Temp. 200–370°C (Typical) | 1,500 – 1,850 | 1,300 – 1,700 | 4 – 8 | — | 49 – 55 HRC |
Data per ASTM A276/A276M and manufacturer typical values. Mechanicals measured on longitudinal specimens at room temperature per ASTM A370. +QT conditions: austenitized 1,010–1,065°C, oil or air quenched, tempered as indicated. Annealed wire (cold-finished, ASTM A580): tensile ≤ 965 MPa. Physical properties: density 7.7 g/cm³, elastic modulus 200 GPa, thermal conductivity 23 W/m·K at 100°C. Custom heat treatment to intermediate hardness levels and mechanical test certification beyond standard minimums available through SHUNFU METAL’s technical team.