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Alloy Steel dealers in UAE

AISI 4145 / 4145H

AISI 4145 / 4145H — the standard CrMo alloy steel for oil & gas drill collars, HWDP, and BHA components per API Spec 7-1. Higher carbon than 4140 (0.43-0.49% vs 0.38-0.43%) for greater hardness and wear resistance in downhole service. Available as round bar, heavy hollow bar, and forgings.

Industries Served

Oil & Gas
Aerospace & Defense
Heavy Engineering
Mining

Applications

  • Drill collars for rotary drilling BHA assemblies in UAE and GCC oilfield operations - primary application globally for 4145H material
  • Heavy weight drill pipe (HWDP) body and transition zone components providing weight on bit and BHA stiffness
  • Stabiliser bodies and integral blade stabilisers for directional and vertical drilling BHA configurations
  • Shock sub mandrels, jars, and drilling jar components requiring combined strength and impact resistance
  • Crossover subs, float subs, and bit subs for BHA string connections and fluid control
  • MWD (Measurement While Drilling) and LWD (Logging While Drilling) tool housing mandrels requiring strength and non-magnetic exterior sections
  • Mining drill rods and heavy-duty mining rotary drilling components requiring API-equivalent strength and wear resistance
  • Large-diameter downhole motor (PDM) housing and mandrel components for directional drilling equipment
  • Forged wellhead components and Christmas tree body sections requiring high-strength CrMo alloy steel with API documentation
  • Fishing tool bodies and overshot mandrels for oil well workover and intervention operations

Chemical Composition

0.46 %
C

Carbon

0.43 – 0.49 %

0.25 %
Si

Silicon

0.15 – 0.35 %

0.85 %
Mn

Manganese

0.75 – 1 %

P

Phosphorus

≤ 0.035 %

S

Sulphur

≤ 0.04 %

0.95 %
Cr

Chromium

0.8 – 1.1 %

0.2 %
Mo

Molybdenum

0.15 – 0.25 %

Typical value Range (min–max) Minimum (≥) Maximum (≤) Hover / tap for notes

Standard

ASTM A29 / A29M - current edition

Available Forms

Round Bar

Diameter 50-500 mm. Hot-rolled or forged, Q&T or normalised. Per ASTM A29 / ASTM A304 (4145H). Standard form for drill collar and downhole BHA machining from solid. Larger sections machined to drill collar OD/ID dimensions; larger diameters available from forged bar.

Hollow Bar

Heavy-wall extruded or bored hollow bar. OD 80-450 mm, various wall thicknesses (15-200 mm) and bore sizes (ID typically 50-75 mm for drill collar utility bore). Supplied as API 7-1 Class 1 Q&T. Significantly reduces machining waste for drill collar production. Specify OD x ID x length and required API 7-1 class.

Forging

Open-die forgings, OD 100-2000 mm. For large-diameter BHA components, stabiliser bodies, and MWD/LWD tool housings. Per ASTM A508 / API Spec 7-1. All sizes on request. Lead times apply.

Ring Forging

Ring forgings, OD 100-2000 mm. For large-diameter BHA components, stabiliser bodies, and MWD/LWD tool housings. Per ASTM A508 / API Spec 7-1. All sizes on request. Lead times apply.

Designations & Equivalents

StandardDesignationNotes
AISI / SAE4145—
AISI / SAE4145HH-band hardenability variant per ASTM A304
UNSG41450—
UNSH41450H-band hardenability variant
ASTMA29 Grade 4145Bar designation per ASTM A29
ASTMA304 Grade 4145HH-band bar designation per ASTM A304
Common Name4145H Class 1 or Class 2API Spec 7-1 drill collar material designation
Common NameDrill Collar Steel—
Common Name4145 Modified (4145 MOD)Variant designation

Compliance & Certification

StandardStatusNotes
EN 10204 3.1SuitableMill Test Certificate - standard with all supply.
EN 10204 3.2ConditionalIndependent third-party Mill Test Certificate - available on request.
NACE MR0175 / ISO 15156Requires ConfirmationApplicable only at 22 HRC max (248 HB). Standard API 7-1 Q&T may not be NACE compliant; verify hardness on MTC at order stage.
API Spec 7-1ConditionalAPI Spec 7-1 compliance (including full mechanical test report with Charpy impact data) available from qualified mill sources - specify at order stage.

Specifications

Mechanical Properties

Values are minimums unless noted; hardness is a maximum.

PropertyAISI 4145 / 4145H — ASTM A29 / A29M — Quenched & Tempered (Q&T)DefaultAISI 4145 / 4145H — API Spec 7-1 — Q&T API 7-1 Class 1AISI 4145 / 4145H — ASTM A29 / A29M — Normalised
Tensile Strength (UTS)range965–1100 MPaTypical: 1030 MPaCondition: Room temp, longitudinalNotes: Slightly higher than 4140 Q&T due to higher carbon. Values for sections to 100 mm.965 MPaTypical: 1030 MPaCondition: Room temp, longitudinalNotes: API Spec 7-1 Class 1 minimum 140 ksi (965 MPa). Per certified test report.965–1100 MPaTypical: 1030 MPaCondition: Room tempNotes: Note: 4145 normalises to high strength due to high hardenability.
Yield Strength (0.2% Proof Stress)range827–965 MPaTypical: 896 MPaCondition: Room tempNotes: 0.2% offset.827 MPaTypical: 896 MPaCondition: Room tempNotes: API Spec 7-1 Class 1 minimum 120 ksi (827 MPa). The defining Class 1 requirement.655–827 MPaTypical: 740 MPaCondition: Room temp
Elongationmin13 %Typical: 16 %Condition: 50 mm gauge length13 %Typical: 16 %Condition: 50 mm gauge lengthNotes: API Spec 7-1 Class 1 minimum 13%.10 %Typical: 14 %Condition: 50 mm gaugeNotes: Lower than Q&T.
Reduction of Areamin45 %Typical: 55 %Condition: Longitudinal45 %Typical: 55 %Condition: LongitudinalNotes: API Spec 7-1 Class 1 minimum 45%.30 %Typical: 45 %Condition: Longitudinal
Hardnessrange22–30 HRCTypical: 26 HRCCondition: Surface, Rockwell CNotes: NACE MR0175 limit: 22 HRC max. Upper range of standard Q&T may exceed NACE limit.22–30 HRCTypical: 26 HRCCondition: Surface and cross-section surveyNotes: Hardness survey across full cross-section required per API 7-1. Check NACE sour service requirement vs hardness achieved.280–340 HBTypical: 310 HBCondition: BrinellNotes: Significantly harder than normalised 4140 (152-207 HB).
Impact Energy (Charpy)max54 JCondition: Room temp, V-notchNotes: API 7-1 Class 1 minimum. Verify with Charpy testing for API applications.—27 JCondition: Room tempNotes: Lower than Q&T. NOT suitable for API 7-1 drill collar use without re-Q&T.
Impact Energy (Charpy V-notch)min—54 JTypical: 81 JCondition: Room temp, V-notchNotes: API Spec 7-1 Class 1 minimum 54 J (40 ft-lbf) at room temperature. Full Charpy testing required on CTR.—

Physical Properties

PropertyAISI 4145 / 4145H — ASTM A29 / A29M — Quenched & Tempered (Q&T)DefaultAISI 4145 / 4145H — API Spec 7-1 — Q&T API 7-1 Class 1AISI 4145 / 4145H — ASTM A29 / A29M — Normalised
Density20 degrees C7.85 g/cm37.85 g/cm37.85 g/cm3
Modulus of Elasticity25 degrees C210 GPa210 GPa210 GPa
Thermal Conductivity100 degrees C42 W/m·K42 W/m·K42 W/m·K
Coefficient of Thermal Expansion20-100 degrees C12.3 um/m·°C12.3 um/m·°C12.3 um/m·°C
Specific Heat Capacity20 degrees C475 J/kg·K475 J/kg·K475 J/kg·K
Melting Point / RangeSolidus1430 degrees C1430 degrees C1430 degrees C
ENGINEERING NOTES
Weldability
Poor

4145 / 4145H has limited weldability due to its higher carbon content (CE approximately 0.80-0.90) and is generally not recommended for structural welding in the Q&T condition. For drill collar and BHA assembly, threaded connections (API 7-1 box and pin connections) are used - welding is not a standard joining method for these components. Where repair welding is required on downhole tools: full solution anneal the component first, weld with low-hydrogen consumables (E7018), preheat to 250-300 degrees C, then fully re-Q&T to original API specification - partial re-heat treatment of a welded region only will not restore properties reliably. Post-weld heat treatment without full re-Q&T is not acceptable for API 7-1 drill collar components. Repair filler metals (exception cases only): E7018-1 low-hydrogen SMAW electrode or ER80S-D2 MIG wire; both require 250-300 degrees C preheat and full re-Q&T heat treatment afterward to restore API 7-1 properties.

Machinability
Good

4145 / 4145H machines well in the annealed or normalised condition. In the Q&T condition at standard API 7-1 hardness (22-30 HRC), carbide tooling is required. Machining characteristics are similar to 4140 at equivalent hardness. For drill collar production, the typical machining sequence is: receive as Q&T bar, rough turn to near-final OD/ID, finish machine box and pin connection threads (API 7-1 rotary shoulder connections), finish bore internal utility bore, then apply appropriate surface treatment (phosphate, etc.). Hollow bar reduces the rough boring operation significantly, cutting machining time and material waste.

Overview

AISI 4145 / 4145H (UNS G41450 / H41450) is a chromium-molybdenum alloy steel containing 0.43-0.49% carbon - slightly higher than AISI 4140 (0.38-0.43%) - which provides greater hardness response and wear resistance in heavy-duty downhole drilling applications. 4145H, the H-band hardenability variant per ASTM A304, is the standard material specified in API Spec 7-1 (Specification for Rotary Drill Stem Elements) for drill collars, heavy weight drill pipe (HWDP), stabiliser bodies, and bottom hole assembly (BHA) components. The API 7-1 Class 1 mechanical requirement - minimum yield strength 120 ksi (827 MPa) and minimum UTS 140 ksi (965 MPa) - is achieved by Q&T heat treatment, with Charpy impact testing at room temperature and full hardness survey required on each lot. The tighter H-band hardenability specification ensures consistent Q&T response across the full cross-section of large-diameter drill collar bar (typically 150-250 mm diameter), providing predictable and uniform properties throughout the drill collar wall.

Nifty Alloys supplies AISI 4145 / 4145H from stock in Dubai, UAE, in round bar, hollow bar, and forgings in Q&T and normalised conditions. API Spec 7-1 Class 1 certified material (with full mechanical test reports, Charpy impact data, and hardenability certification) is available from our qualified mill sources - specify at enquiry stage. All material is supplied with EN 10204 3.1 Mill Test Certificates as standard. EN 10204 3.2 third-party inspection is available on request. We deliver across the UAE within 24-48 hours and export to Saudi Arabia, Kuwait, Qatar, Oman, and Bahrain. Contact our team for same-day quotation and stock availability.

Frequently Asked Questions

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AISI 4145 / 4145H is the standard CrMo alloy steel for oil & gas rotary drilling equipment, specified in API Spec 7-1. Primary applications include: drill collars for BHA assemblies in UAE and GCC onshore and offshore drilling operations; heavy weight drill pipe (HWDP) body components; stabiliser bodies and integral blade stabilisers; shock sub and jar mandrels; crossover subs, float subs, and bit subs; MWD/LWD tool housing mandrels; downhole motor (PDM) housing components; and forged wellhead body sections. The higher carbon content (0.43-0.49%) compared to 4140 (0.38-0.43%) provides greater hardness and wear resistance in the abrasive downhole environment, while the H-band hardenability specification (4145H per ASTM A304) ensures consistent Q&T response across large-diameter drill collar sections. 4145H Q&T to API 7-1 Class 1 (120 ksi YS min / 140 ksi UTS min) is the universal drill collar steel specification globally.

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Ras Al Khor Ind. Area-2, Dubai United Arab Emirtates

+971 565450916

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