Project Description
440B (UNS S44003 / 1.4112 / X90CrMoV18 / SUS440B / 90Х18М / 9Cr18MoV) is a high-carbon martensitic stainless steel bar engineered for maximum attainable hardness and exceptional wear resistance in moderately corrosive service environments. Containing 0.75–0.95% carbon with chromium at 16–19%, 440B heat-treats to 58–59 HRC while retaining better corrosion resistance than 440C and substantially higher hardness than 440A. The vanadium-modified EN 1.4112 and GB 9Cr18MoV variants add grain-refinement and tempered-hardness stability through secondary hardening. 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.
440B Stainless Steel — High-Hardness Martensitic Grade
440B belongs to the high-carbon martensitic stainless steel family — alloys that achieve their service properties through quenching from the austenitizing range (1,010–1,065°C) to form hard martensite, followed by tempering at 150–370°C to balance hardness with toughness. Carbon content of 0.75–0.95% enables through-hardening up to 59 HRC, roughly 2–3 HRC points above 440A and only 1–2 HRC below 440C, while the reduced carbon and carbide volume relative to 440C deliver measurably lower quench-cracking risk in complex-section parts. The 16–19% chromium provides oxidation resistance and mild-environment corrosion protection superior to tool steels at equivalent hardness. SHUNFU METAL refines each 440B heat through AOD processing, with LF and VD steps ensuring tight chemistry control, low sulfur for improved transverse properties, and minimal gas content. For critical oil and gas applications, ESR remelting is available to eliminate centerline segregation and achieve superior micro-cleanliness. The ISO 9001 framework governs every stage: incoming raw material verification, spectrometric chemistry checks, heat treatment chart recording, mechanical test sampling per ASTM A370, ultrasonic inspection per ASTM E2375, and final dimensional inspection. API Q1 supplementary requirements — including independent third-party witness testing and retained reference samples — are applied in full for API-governed orders.
Compared to 440A, 440B gains significantly higher as-quenched and tempered hardness through its elevated carbon content, making it the preferred choice where 440A cannot reach the specified hardness floor. Compared to 440C, 440B offers improved corrosion resistance through its lower chromium carbide volume fraction, which leaves more chromium in solid solution, and reduced quench-cracking sensitivity in thick sections. SHUNFU METAL supplies 440B 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 EN 10204 3.1 certificates.
Equivalent Grades of 440B Across International Standards
| Standard / Specification | Designation |
|---|---|
| ASTM A276 / A276M | Type 440B (UNS S44003) |
| ASTM A580 / ASTM A959 | 440B (S44003) Wire / Grade Reference |
| ASTM A473 | Type 440B (S44003) Forgings |
| EN 10088-3 | X90CrMoV18 (1.4112) |
| DIN EN 10088-3; DIN 17440 | X90CrMoV18 (1.4112) |
| JIS G4303 | SUS 440B |
| GOST 5632 | 90Х18М (90X18M) |
| GB/T 1220 / GB/T 3280 | 9Cr18MoV / 90Cr18MoV |
Oil & Gas Industry Applications
440B stainless steel bars find extensive application across upstream, midstream, and downstream petroleum operations wherever extreme surface hardness, edge retention, and galling resistance converge. The grade is the material of choice for hardened valve internals subjected to high-cycle contact stress, wear-critical pump components in abrasive produced-fluid service, and precision bearing elements in downhole and surface rotating equipment. SHUNFU METAL supplies 440B bars to valve manufacturers, pump OEM shops, bearing houses, and machining workshops supporting the global oil and gas industry, with ISO 9001 and API Q1 certification ensuring full compliance with end-user quality and lot-traceability requirements.
Valve Balls & Seats
Through-hardened ball-valve balls and seat rings for API 6D and API 6A gate, ball, plug, and floating-ball valves in production and gathering service.
Valve Stems & High-Pressure Trim
Hardened stems, cages, discs, and internal trim for control valves and chokes in high-pressure hydrocarbon and gas-lift service.
Ball & Roller Bearings
Hardened bearing races and rolling elements for downhole drilling motors, mud-pump connecting rods, top drives, and rotating control devices.
Pump Wear Rings & Bushings
Case and impeller wear rings, shaft sleeves, and throat bushings for API 610 centrifugal pumps handling abrasive produced-water and multiphase fluids.
Compressor Valve Plates
Hardened reciprocating compressor valve plates, springs, and seats for natural gas gathering, gas-lift compression, and vapor-recovery compressor service.
Needle Valves & Metering Devices
Hardened needle tips, tapered plugs, and flow-control metering stems for chemical injection quills, sampling systems, and instrument isolation valves.
Choke & Throttle Components
Hardened flow beans, throttle bushings, and orifice plates for adjustable and fixed chokes in pressure letdown stations and wellhead choke manifolds.
High-Hardness Fasteners & Pins
Shear pins, set screws, and wear-resistant fasteners requiring surface hardness above 54 HRC for critical bolted joints and alignment fixtures in field equipment.
Instrument & Gauge Components
Hardened pivots, anvils, and sliding contacts for pressure gauges, dead-weight testers, and mechanical metering equipment on well-test and process skids.
Supply Range of 440B Stainless Steel Bar
SHUNFU METAL manufactures and stocks 440B stainless steel in hot-rolled, forged, and cold-finished bar forms covering the dimensional spectrum required by valve, bearing, and pump component manufacturers worldwide. Hot-rolled bars are produced from continuous-cast bloom through our bar mill; forged bars utilize open-die press forging with upset reduction ratios ≥ 4:1 to ensure full structural consolidation and uniform grain flow in large sections. Cold-finished bars are centerless-ground or peeled to IT 7–8 tolerances. Every heat undergoes ultrasonic inspection per ASTM E2375 / EN 10228-3, dimensional verification 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 EN 10204 3.1 certificates linking product to melt chemistry, heat treatment chart records, and mechanical test results. ESR-remelted stock is available for applications demanding maximum micro-cleanliness and isotropic properties.
| Product Form | Diameter / Section Range | Length | Surface / Condition |
|---|---|---|---|
| Hot-Rolled Round Bar | ⌀8 mm – ⌀200 mm | 3,000 – 6,000 mm | Annealed & Peeled / Black |
| Forged Round Bar | ⌀100 mm – ⌀1,000 mm | 2,000 – 8,000 mm | Annealed / Rough Machined |
| Hot-Rolled Flat Bar | 5–100 mm thick × 50–500 mm wide | 3,000 – 6,000 mm | Black / Ground / Machined |
| Forged Flat / Block | 100–500 mm thick × 200–1,000 mm wide | 1,000 – 5,000 mm | Annealed / Rough Machined |
| Cold-Finished / Ground Bar | ⌀5 mm – ⌀100 mm | 1,000 – 4,000 mm | Centerless Ground / Polished |
Bars supplied in the annealed condition (max 96 HRB / ~269 HB) for customer machining and in-house hardening, or fully heat-treated to target hardness per specification (53–59 HRC range). Non-standard diameters, stepped shafts, hollow bars, and cut-to-length pieces available on inquiry. Electrolytic cut for hard-tempered stock to avoid thermal end-zone alteration. PKO/PE anti-rust coating, VCI wrapping, and sea-worthy timber crate packing standard for export. Custom packaging configurations and batch-level third-party inspection by SGS or TÜV are available on request.
Chemical Composition of 440B (EN 10088-3 / ASTM A276)
The chemical composition of 440B is defined under both European and North American standards, with a key distinction: EN 10088-3 specifies the vanadium-modified X90CrMoV18 (1.4112) variant featuring mandatory molybdenum at 0.90–1.30% and vanadium at 0.07–0.12%, while ASTM A276 defines 440B as a simpler Cr-only + optional Mo grade. The EN 1.4112 chemistry offers improved tempered-hardness stability through vanadium’s grain-refinement effect and enhanced pitting resistance from the higher Mo content. SHUNFU METAL controls each heat to the tighter overlap range of both specifications through AOD + LF + VD refining, with ESR remelting available for critical applications. 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 X90CrMoV18 (1.4112) | ASTM A276 Type 440B (S44003) |
|---|---|---|
| Carbon (C) | 0.85 – 0.95 | 0.75 – 0.95 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 | ≤ 0.030 |
| Chromium (Cr) | 17.0 – 19.0 | 16.0 – 18.0 |
| Molybdenum (Mo) | 0.90 – 1.30 | ≤ 0.75 |
| Vanadium (V) | 0.07 – 0.12 | — |
All values in weight percent (wt%). Cast analysis per respective standard. EN 10088-3 additionally restricts Ni ≤ 0.30%. SHUNFU METAL’s AOD practice typically achieves P ≤ 0.025% and S ≤ 0.008% for standard-grade, and P ≤ 0.020% / S ≤ 0.005% for ESR-grade, well inside both specification maxima. The GB/T 1220 9Cr18MoV chemistry (C 0.85–0.95, Cr 17.0–19.0, Mo 1.00–1.30, V 0.07–0.12, Si ≤ 0.80, Mn ≤ 0.80) closely aligns with EN 1.4112 and is available dual-certified upon request.
Mechanical Properties — Annealed & Hardened Conditions
440B 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. Peak hardness of 58–59 HRC is achieved at the lowest tempering temperatures (~150°C); increasing tempering temperature to 300–370°C reduces hardness by 3–6 HRC points while improving ductility and impact resistance. Tempering between 370–540°C is avoided due to the risk of chromium carbide precipitation with associated loss of corrosion resistance. 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. For oil-quenched heavy sections, immediate tempering after quench-cooling to 50–60°C is mandatory to prevent delayed cracking.
| Condition | Tensile Rm (MPa) | Yield Rp0.2 (MPa) | Elong. A5 (%) | RA Z (%) | Hardness |
|---|---|---|---|---|---|
| +A Annealed (ASTM A276) | ≥ 740 | ≥ 425 | ≥ 18 | — | ≤ 96 HRB (≤ 269 HB) |
| +QT315 Hardened & Temp. 315°C (ASTM A276) | ≥ 1,930 | ≥ 1,860 | ≥ 3 | ≥ 15 | ≥ 55 HRC |
| +QT200 Hardened & Temp. 150–200°C (Max Hardness) | 1,900 – 2,100 | 1,700 – 2,000 | 2 – 4 | — | 56 – 59 HRC |
| +QT300 Hardened & Temp. 200–370°C (Balanced) | 1,600 – 1,950 | 1,400 – 1,800 | 3 – 6 | — | 53 – 57 HRC |
| +A Cold-Finished Wire, Annealed (ASTM A580) | ≤ 965 | — | — | — | ≤ 96 HRB |
Data per ASTM A276/A276M, EN 10088-3, and manufacturer typical values. Mechanicals measured on longitudinal specimens at room temperature per ASTM A370 / EN ISO 6892-1. +QT conditions: austenitize 1,010–1,065°C, oil or air quench, temper as indicated, air cool. Isothermal annealing at 690°C for 4 hours available for improved machinability. Physical properties: density 7.7 g/cm³, elastic modulus 200 GPa, thermal conductivity 24.2 W/m·K at 100°C, coefficient of thermal expansion 10.1–11.7 μm/m·°C (0–538°C). Forging range: 925–1,175°C. SHUNFU METAL’s technical team provides application-specific heat treatment optimization and mechanical test certification beyond standard minimums upon request.