AISI 4145H
It is a high-strength, chromium-molybdenum (chromoly) alloy steel specifically designed for applications requiring exceptional hardenability, toughness, and fatigue resistance.
Descriptions
1. Chemical Composition
AISI 4145H features a higher carbon content compared to AISI 4140, enhancing its strength and hardenability. Chromium and molybdenum improve wear resistance and high-temperature stability.
| Element | Composition (% by Weight) | Role |
| Carbon (C) | 0.43-0.48 | Enhances hardness and tensile strength. |
| Manganese (Mn) | 0.75-1.00 | Improves hardenability and toughness. |
| Silicon (Si) | 0.15-0.35 | Strengthens ferrite and deoxidizes molten steel. |
| Chromium (Cr) | 0.80-1.10 | Boosts hardenability, wear, and corrosion resistance |
| Molybdenum (Mo) | 0.15-0.25 | Enhances high-temperature strength and creep resistance. |
| Phosphorus (P) | 0.035 max | Controlled impurity (minimizes brittleness). |
| Sulfur (S) | 0.040 max | Controlled impurity (improves machinability in small amounts). |
| Iron (Fe) | Balance | Base metal. |
2. Mechanical Properties
AISI 4145H forgings achieve superior mechanical performance through heat treatment (e.g., quenching and tempering). Hardenability bands (H-code) ensure uniformity in large cross-sections.
| Property | As-Forged | Quenched &Tempered | Normalized | Test Standard |
| Tensile Strength | 700-900 MPa | 1000-1200 MPa | 750-900 MPa | ASTME8 |
| Yield Strength (0.2% offset) | 500-700MPa | 850-1050 MPa | 550-700 MPa | ASTME8 |
| Elongation (%in 50 mm) | 12-18% | 10-15% | 15-20% | ASTME8 |
| Reduction of Area | 40-50% | 35-45% | 45-55% | ASTME8 |
| Hardness (Brinell) | 220-270HB | 302-375HB | 200-250 HB | ASTME10 |
| Impact Toughness (Charpy V) | 30-50 J(room temp) | 20-40J | 40-60J | ASTME23 |
3. Key Advantages
Controlled Hardenability: Uniform properties in thick sections (H-grade compliance).
High Fatigue Strength: Resists cyclic loading in drilling and mining equipment.
Wear Resistance: Suitable for abrasive environments.
4. Typical Product Names
Forged Drill Collars
Tool Joints for Drill Pipes
Heavy-Duty Gear Blanks
Turbine Rotor Shafts
High-Pressure Valve Bodies
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CONTACT US
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B-2007,Chuanmei Building,Taishan Street,Taian City，Shandong, China
Call Us
+86 0538 6368027
Email Address
Sales@tiptopforging.com
Applications
High-stress landing gear parts and engine mounts.
Drill collars, tool joints, blowout preventer (BOP) components.
Shafts, crusher parts, heavy-duty gears.
Turbine shafts, rotor components, high-pressure valves.
