Project Description
AISI 4130 P+X Chromium-Molybdenum Steel Bar — Enhanced Performance for Critical Oil & Gas Applications
AISI 4130 is a low-alloy chromium-molybdenum (CrMo) steel that has anchored oil and gas, drilling, and mining material specifications for generations. Its defining alloying elements — chromium (0.80–1.10%) and molybdenum (0.15–0.25%) — work in concert to deliver deep hardenability, outstanding tempering stability, and inherent resistance to hydrogen-induced cracking, establishing this grade as the foundational choice for high-pressure, safety-critical, and sour-environment components worldwide.
At Hunan ShunFu Metal Material Co., Ltd., we do not simply distribute standard 4130. Our proprietary AISI 4130 P+X (Performance + X-factor) variant elevates this grade through premium melting cleanliness, tightened phosphorus and sulfur chemistry limits of 0.020% each, controlled calcium treatment for inclusion morphology management, advanced vacuum degassing to below 2 ppm hydrogen, and a specialized Quench-Temper-Control (QTC) protocol developed in direct alignment with API 6A requirements.
The measurable result: 20–30% higher low-temperature impact values, 15–20% improved fatigue endurance, and demonstrably enhanced sulfide stress cracking resistance compared to standard AISI 4130 produced to ASTM A322 chemistry limits alone.
As an API Q1 and ISO 9001 certified manufacturer with a dedicated team of 22 metallurgy and materials engineers, ShunFu Metal is a proven supply partner to the world's top-10 oilfield service companies, with verified export records spanning more than 52 countries. Our end-to-end manufacturing capability — from EAF melting through calibrated heat treatment and precision CNC machining — places every 4130 P+X bar under a single, fully traceable quality chain from ladle to dispatch.
Equivalent Grades
| Region / Standard | Designation |
|---|---|
| USA — AISI/SAE | 4130 (UNS G41300) |
| USA — ShunFu Proprietary | 4130 P+X |
| Europe — EN 10083-3 | 25CrMo4 / 1.7218 |
| Germany — DIN | 25CrMo4 |
| United Kingdom — BS | 708M25 |
| France — AFNOR | 25CD4 |
| Japan — JIS | SCM430 |
| China — GB | 30CrMo |
| Russia — GOST | 30KhMA |
Applications
AISI 4130 P+X from ShunFu Metal is purpose-built for applications where standard 4130 performance margins are no longer sufficient and material failure carries safety, financial, or reputational consequences. Every product form listed below is available directly from ShunFu Metal's factory — from ready stock or produced to customer specification — with full heat treatment, precision machining, and certification services performed in-house.
Oil & Gas — Wellhead and Pressure Control Equipment
- High-Pressure Wellhead Body Forgings: ShunFu Metal supplies 4130 P+X as large-diameter quenched-and-tempered forged round bars and rough-turned blanks dimensioned to API 6A PSL 3&4 wellhead body requirements. Our certified QTC heat treatment procedure delivers consistent cross-section hardness uniformity meeting NACE MR0175/ISO 15156 hardness ceiling requirements on every production lot, without exception.
- Blowout Preventer (BOP) Structural Component Blanks: Delivered as heavy-section smooth-turned bars up to 304.8 mm (12″) in diameter, with 100% ultrasonic testing per ASTM A388 completed in ShunFu Metal's in-house inspection facility before dispatch. The P+X-improved microstructural cleanliness materially enhances ultrasonic signal-to-noise ratio, providing greater confidence in subsurface flaw detection for these safety-critical components.
- Sour Service Valve Body Blanks: The P+X tightened S and P limits of 0.020% each, combined with calcium treatment that eliminates elongated manganese sulfide stringers, make this material the correct selection for H₂S-containing service. ShunFu Metal can supply valve body blanks with NACE TM0177 Method A test results included in the standard certification package.
- Safety-Critical Choke and Kill Manifold Blanks: ShunFu Metal produces these as precision-turned round bar sections with guaranteed through-thickness property uniformity, documented by core mechanical testing on diameters above 285.8 mm. This core verification capability — sampling and testing at the full bar cross-section — reflects our manufacturing discipline for safety-critical pressure-containing applications.
- Subsea Tree and Connector Component Blanks: Supplied in P+X tempered condition with enhanced corrosion fatigue resistance derived from the refined, homogeneous tempered martensitic microstructure characteristic of the P+X process. ShunFu Metal supplies these blanks to subsea equipment manufacturers in North America and Europe.
Drilling Engineering
- Drill Collar Blanks: Produced as solid round bar or heavy-wall hollow bar blanks, drawing directly on ShunFu Metal's extensive drill collar manufacturing expertise. Our BTA deep-hole boring and CNC turning lines convert 4130 P+X round bar stock into precision drill collar blanks machined to customer-specified bore diameters, OD tolerances, and connection geometry.
- Drill String Stabilizer Sleeves: Supplied as rough-bored hollow bar blanks in P+X quenched-and-tempered condition, pre-processed for direct weld-on blade attachment or customer finish machining. The improved fatigue endurance of the P+X material directly extends service intervals in high-RPM rotating drill string applications.
- Downhole Tool Mandrels: Produced as precision-bored, CNC-turned tubular sections with controlled bore finish and concentricity. ShunFu Metal's Long Distance Gunhole Drilling capability enables the production of mandrel blanks with exceptionally long, straight through-bores in a single pass — a specific advantage for extended-reach downhole tool designs.
- MWD/LWD Tool Housings: Machined as CNC-turned tubular sections to tight wall thickness and concentricity tolerances. The P+X microstructure's 15–20% improved fatigue endurance limit is directly relevant to MWD/LWD housing applications, where resonant vibration in the BHA accumulates cyclic loading hours rapidly and material fatigue is a documented failure mechanism.
Mining and Heavy Engineering
- Rock Drill Barrel and Shank Adapter Blanks: Drawing on ShunFu Metal's dedicated Rock Drill Steel product line and deep experience in percussion drilling materials, 4130 P+X is supplied as pre-drilled hollow bar stock for high-impact applications demanding simultaneous toughness and fatigue resistance.
- Hydraulic Cylinder Barrels: Supplied as BTA-bored hollow bars with controlled internal surface finish, ready for finish honing. ShunFu Metal's Long Distance Gunhole Drilling capability enables long, straight bore passes in a single setup, producing cylinder barrel blanks with bore straightness within 0.5 mm/m as standard.
- High-Stress Load-Bearing Structural Forgings: Supplied as quenched-and-tempered round forged bars for critical lifting, hoisting, and load-bearing structural components in mining environments where formally traceable mechanical test documentation is required by the end-client safety management system.
Specifications & Standards
AISI 4130 P+X as manufactured by ShunFu Metal is produced in full conformance with the following internationally recognized specifications. Only standards to which this grade genuinely applies are listed below.
| Standard | Designation | Product Scope |
|---|---|---|
| ASTM A29/A29M | Grade 4130 | Steel Bars, Carbon and Alloy, Hot-Wrought — dimensional and general manufacturing requirements |
| ASTM A322 | Grade 4130 | Steel Bars, Alloy, Standard Grades — chemical composition requirements |
| ASTM A388 | — | Standard Practice for Ultrasonic Examination of Steel Forgings — applied to 100% UT inspection of all P+X bars |
| API 6A | PSL 3 & PSL 4 | Specification for Wellhead and Tree Equipment — material qualification, heat treatment, mechanical, and inspection requirements |
| NACE MR0175 / ISO 15156 | — | Materials for Use in H₂S-Containing Environments in Oil and Gas Production — sour service material compliance |
| NACE TM0177 | Method A | Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking — batch-level SSC performance verification |
| SAE J404 | 4130 | Chemical Compositions of SAE Alloy Steels — chemistry reference |
ShunFu Metal organizes every production lot of AISI 4130 P+X strictly in accordance with the specifications listed above and is able to issue material test reports and mill test certificates referencing the applicable standard designation — EN 10204 3.1 as standard, EN 10204 3.2 by arrangement — to satisfy customer incoming inspection and project documentation requirements.
Available Sizes & Delivery
ShunFu Metal supplies AISI 4130 P+X as hot-rolled or forged round bars from 76.2 mm (3″) to 304.8 mm (12″) diameter, peeled or smooth-turned, in the P+X QTC quenched-and-tempered condition. In-house BTA boring, CNC lathe and milling, and Long Distance Gunhole Drilling convert solid bar directly into precision hollow bar sections to order.
| Order Type | MOQ | Indicative Lead Time |
|---|---|---|
| Standard stock diameters — ready inventory | 1 piece | ~7 days |
| Custom forged or rolled bars, specified dimensions/levels | 3 metric tons | ~30 days |
| Small-batch special heats — in-house induction furnace | 3–5 metric tons | ~30 days |
| Large-volume production orders — EAF (30–60 MT capacity) | 30 metric tons | Accelerated schedule |
Chemical Composition
ShunFu Metal verifies the chemical composition of every heat of AISI 4130 P+X through in-house optical emission spectrometry (OES) conducted on ladle samples prior to casting, ensuring that all elements — including residual elements critical to sour service performance — comply strictly with P+X specification limits before any material enters the downstream processing chain.
| Element | Standard AISI 4130 Min (%) | Standard AISI 4130 Max (%) | ShunFu 4130 P+X Min (%) | ShunFu 4130 P+X Max (%) |
|---|---|---|---|---|
| Carbon (C) | 0.28 | 0.33 | 0.28 | 0.33 |
| Chromium (Cr) | 0.80 | 1.10 | 0.80 | 1.10 |
| Manganese (Mn) | 0.40 | 0.60 | 0.40 | 0.60 |
| Molybdenum (Mo) | 0.15 | 0.25 | 0.15 | 0.25 |
| Silicon (Si) | 0.15 | 0.35 | 0.15 | 0.35 |
| Phosphorus (P) | — | 0.035 | — | 0.020 |
| Sulfur (S) | — | 0.040 | — | 0.020 |
Bold values denote tightened P+X limits versus standard AISI 4130. In addition to the tabulated controls, ShunFu Metal's P+X process incorporates controlled calcium treatment for inclusion shape modification to eliminate elongated MnS stringers, alongside microalloying additions within standard composition limits to maintain consistent ASTM grain size 7–8 — both verified metallographically on every production lot.
Melting & Processing
ShunFu Metal's standard P+X melt route is EAF + LF + VD, with extended desulfurization and vacuum degassing targeting H₂ below 2 ppm. ESR is available for superior inclusion cleanliness requirements. Customers select the route matched to their specific application criticality — ShunFu Metal's technical team advises on the optimal process path.
Mechanical Properties
All properties below are measured on AISI 4130 P+X bars in the quenched-and-tempered condition, processed using ShunFu Metal's proprietary QTC procedure, qualified in full alignment with API 6A requirements at the 75 ksi minimum yield strength level.
Room Temperature Tensile Properties — Q+T (75 ksi Yield Level)
| Property | Standard AISI 4130 | ShunFu 4130 P+X |
|---|---|---|
| 0.2% Yield Strength (min) | 75 ksi (517 MPa) | 75 ksi (517 MPa) |
| Ultimate Tensile Strength (min) | 95 ksi (655 MPa) | 95 ksi (655 MPa) |
| Elongation (min) | 18% | 20% |
| Reduction of Area (min) | 35% | 45% |
| Hardness | 18–22 HRC / 217–237 HBW | 18–22 HRC / 217–237 HBW |
Charpy V-Notch Impact Energy
| Test Temperature | Standard AISI 4130 (Average) | ShunFu 4130 P+X (Average) |
|---|---|---|
| +23°C (+73°F) | 100 J (74 ft-lb) | 130 J (96 ft-lb) |
| −60°C (−76°F) | 27 J (20 ft-lb) | 35 J (26 ft-lb) |
| −75°C (−103°F) | 19 J (14 ft-lb) | 25 J (18 ft-lb) |
Prior to shipment, ShunFu Metal issues mechanical test reports — generated by our in-house laboratory or an accredited third-party test facility — fully traceable to the specific heat number and production batch, providing complete data accountability across your supply chain documentation.
Heat Treatment
| Process | Temperature Range | Minimum Soak Time | Cooling Method |
|---|---|---|---|
| Normalizing (where specified) | 870–925°C (1600–1700°F) | 1 hr per 25 mm of cross-section | Air cool |
| Austenitizing (Hardening) | 855–900°C (1570–1650°F) | 1 hr per 25 mm of cross-section | Oil or polymer quench |
| Tempering — P+X QTC Protocol | 595–680°C (1100–1255°F) | 1 hr per 25 mm of cross-section | Air cool or furnace cool |
| Stress Relieving (where specified) | 540–650°C (1000–1200°F) | As agreed with customer | Slow furnace cool |
ShunFu Metal maintains all heat treatment furnaces under a rigorous API-standard calibration program, with documented furnace temperature uniformity surveys (TUS) and system accuracy tests (SAT) conducted on a scheduled basis. This discipline ensures uniform, repeatable thermal profiles and eliminates batch-to-batch property scatter across all P+X production. Complete digital heat treatment cycle records — including thermocouple data and ramp profiles — are archived and provided as part of the standard certification package with every order.
Surface Finish & Machining
ShunFu Metal delivers 4130 P+X as peeled or smooth-turned bar (Ra ≤ 3.2 µm, tolerance h9–h11), CNC finish-turned (Ra ≤ 1.6 µm, h7–h8), or BTA-bored hollow sections (bore Ra ≤ 1.6 µm, straightness ≤ 0.5 mm/m). Roller burnishing achieves bore Ra ≤ 0.4 µm. Shot peening is available for fatigue-critical components. All operations are executed in-house across ShunFu Metal's dedicated CNC and BTA equipment lines.
Quality Assurance & Inspection
Under ShunFu Metal's API Q1 and ISO 9001 certified QMS, every 4130 P+X lot undergoes in-house OES composition verification, post-heat-treatment hardness survey, 100% UT to ASTM A388 at API 6A PSL 3&4 acceptance criteria, full mechanical testing (tensile, CVN impact, hardness), and metallographic grain size verification. EN 10204 3.1 is standard; 3.2 is negotiable. SGS, TÜV, and CNSA third-party inspection arranged on request.
Packing & Shipping
Black-surface bars are steel-wire bundled with protective inter-bar separators. Peeled, smooth-turned, or precision-machined products receive individual anti-rust oil treatment, polyethylene stretch-film wrapping, and wooden crate or steel-framed packaging engineered to maintain surface finish and dimensional accuracy. All products are treated with rust-inhibiting oil specified for long-duration ocean freight.
With active export experience covering more than 52 countries — including the United States, United Kingdom, Germany, Norway, the United Arab Emirates, Brazil, Singapore, and Australia — ShunFu Metal's export logistics team tailors packaging formats, bar marking, and documentation packages to any destination port requirement. A standard export package includes commercial invoice, packing list, certificate of origin, EN 10204 3.1 mill test report, and any requested third-party inspection certificates.
Frequently Asked Questions
Can ShunFu Metal supply AISI 4130 P+X bar to API 6A PSL 3 and PSL 4 requirements, including NACE MR0175 sour service compliance?
Yes. ShunFu Metal's AISI 4130 P+X is specifically engineered and production-qualified to meet API 6A PSL 3 and PSL 4 material requirements, manufactured in full conformance with NACE MR0175/ISO 15156 for sour service. Our API Q1 certified system and proprietary QTC heat treatment provide complete documentation: tensile, CVN, hardness surveys, 100% UT to ASTM A388, and fully traceable MTRs per heat number.
What is the minimum order quantity for AISI 4130 P+X round bar, and how quickly can ShunFu Metal deliver?
For stock diameters, single-bar orders ship in approximately 7 days. Custom specifications carry a typical MOQ of 3 metric tons and a lead time of about 30 days. Small-scale qualification heats from 3–5 metric tons are available using our in-house induction furnace, allowing material testing without large initial commitments.
How does ShunFu Metal verify that 4130 P+X meets NACE MR0175 hardness limits and sulfide stress cracking resistance?
We conduct full cross-section hardness surveys after QTC heat treatment, verifying HRC ≤ 22. For SSC qualification beyond hardness testing, we can supply NACE TM0177 Method A test results on production-lot specimens, meeting the evidence level required by top-tier oil & gas operators.
What is the difference between ShunFu Metal's AISI 4130 P+X and standard 4130 bar from distributors?
Standard 4130 from distributors typically meets only ASTM A322 chemistry. ShunFu Metal’s 4130 P+X is manufactured under API Q1 with tightened P/S limits, calcium treatment, vacuum degassing below 2 ppm H₂, proprietary QTC heat treatment, 100% ultrasonic testing, and complete EN 10204 3.1 certification — ready for safety-critical pressure-containing applications.
