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AISI 4340 Steel Round Bar - High Tensile Strength, Shock and Impact Resistant, Wear and Abrasion Resistant
商品の詳細
| 直径範囲 | 6-630mm | 炭素含有量 | 0.38~0.43% |
|---|---|---|---|
| マンガンの内容 | 0.60~0.80% | リン含有量 | 0.035% |
| 硫黄分 | 0.040% | シリコン含有量 | 0.15~0.35% |
| ニッケル含有量 | 1.65~2.00% | クロムの内容 | 0.70~0.90% |
| モリブデン含有量 | 0.20~0.30% | 抗張力 | 930~1080MPa |
| 降伏強さ | 740MPa | 伸長 | 12% |
| 耐衝撃性 | 47 J | Brinell硬度 | 269-331HB |
| 熱伝導率 | 44.5W/mK | ||
| ハイライト | High Tensile Strength AISI 4340 Steel Round Bar,Shock and Impact Resistant 40CrNiMoA Round Bar,Wear and Abrasion Resistant SNCM439 Alloy Steel Bar |
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製品の説明
40CrNiMoA BS S535/AMS 6350 AISI 4340 Round Bar JIS Sncm439
AISI 4340 steel is a medium carbon, low alloy steel known for its exceptional toughness and strength in relatively large sections. As a nickel chromium molybdenum steel, 4340 alloy steel is typically supplied hardened and tempered in the tensile range of 930-1080 Mpa. This material offers excellent shock and impact resistance along with superior wear and abrasion resistance in the hardened condition.
Specifications and Standards
| Country | USA | Britain | Britain | Japan |
|---|---|---|---|---|
| Standard | ASTM A29 | EN 10250 | BS 970 | JIS G4103 |
| Grades | 4340 | 36CrNiMo4/1.6511 | EN24/817M40 | SNCM 439/SNCM8 |
Chemical Composition
| Standard | Grade | C | Mn | P | S | Si | Ni | Cr | Mo |
|---|---|---|---|---|---|---|---|---|---|
| ASTM A29 | 4340 | 0.38-0.43 | 0.60-0.80 | 0.035 | 0.040 | 0.15-0.35 | 1.65-2.00 | 0.70-0.90 | 0.20-0.30 |
| EN 10250 | 36CrNiMo4/1.6511 | 0.32-0.40 | 0.50-0.80 | 0.035 | 0.035 | <=0.40 | 0.90-1.20 | 0.90-1.2 | 0.15-0.30 |
| BS 970 | EN24/817M40 | 0.36-0.44 | 0.45-0.70 | 0.035 | 0.040 | 0.1-0.40 | 1.3-1.7 | 1.00-1.40 | 0.20-0.35 |
| JIS G4103 | SNCM 439/SNCM8 | 0.36-0.43 | 0.60-0.90 | 0.030 | 0.030 | 0.15-0.35 | 1.60-2.00 | 0.60-1.00 | 0.15-0.30 |
Mechanical Properties
| Condition | Ruling Section (mm) | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Izod Impact (J) | Brinell Hardness |
|---|---|---|---|---|---|---|
| T | 250 | 850-1000 | 635 | 13 | 40 | 248-302 |
| T | 150 | 850-1000 | 665 | 13 | 54 | 248-302 |
| U | 100 | 930-1080 | 740 | 12 | 47 | 269-331 |
| V | 63 | 1000-1150 | 835 | 12 | 47 | 293-352 |
| W | 30 | 1080-1230 | 925 | 11 | 41 | 311-375 |
| X | 30 | 1150-1300 | 1005 | 10 | 34 | 341-401 |
| Y | 30 | 1230-1380 | 1080 | 10 | 24 | 363-429 |
| Z | 30 | 1555- | 1125 | 5 | 10 | 444- |
Thermal Properties
| Properties | Metric | Imperial |
|---|---|---|
| Thermal expansion co-efficient | 12.3 µm/m°C | 6.83 µin/in°F |
| Thermal conductivity | 44.5 W/mK | 309 BTU in/hr.ft².°F |
Heat Treatment Processes
Forging
Preheat 4340 steel to 1150°C - 1200°C maximum for forging, holding until temperature is uniform throughout the section. Do not forge below 850°C. Following forging, cool the workpiece as slowly as possible in sand or dry lime to prevent cracking.
Stress Relieving
Heat to 600°C - 650°C, hold until uniform temperature, soak for 1 hour per 25mm section, and cool in still air.
Annealing
Full anneal at 844°C (1550°F) followed by controlled furnace cooling at a rate not faster than 10°C (50°F) per hour down to 315°C (600°F), then air cool.
Tempering
Temper at 232°C (450°F) for 260-280 ksi strength range, or at 510°C (950°F) for 125-200 ksi strength range. Avoid tempering between 250°C - 450°C due to temper brittleness.
Surface Hardening
Pre-hardened 4340 steel can be surface hardened by flame or induction hardening, achieving case hardness exceeding Rc 50. Heat quickly to 830°C - 860°C followed by oil or water quenching.
Nitriding
Hardened and tempered 4340 can be nitrided at 500°C - 530°C for 10-60 hours, achieving surface hardness of 600-650HV with minimal effect on core tensile strength.
Machining and Welding
Machining is best performed in the annealed or normalized and tempered condition. In high strength conditions (200 ksi or greater), machinability decreases to 25-10% of the annealed condition. Welding in hardened and tempered condition is not recommended. If necessary, pre-heat to 200-300°C and stress relieve at 550-650°C after welding.
Applications
- Aircraft Landing Gear
- Automotive Components
- Oil and Gas Drilling Equipment
- Forging Applications
- Machine Building
- Power Transmission Gears and Shafts
- Heavy Duty Shafts, Axles, Spindles
- Couplings, Pins, Chucks, Molds
Available Sizes and Conditions
Round Bar Diameter: 12-380mm
Available in round bars, flat bars, plates, and blocks in various conditions including pre-hardened, hot rolled, annealed, quenched and tempered, with surface conditions from black to pre-machined, grinding, and polish.
Available in round bars, flat bars, plates, and blocks in various conditions including pre-hardened, hot rolled, annealed, quenched and tempered, with surface conditions from black to pre-machined, grinding, and polish.
Product Images
Why Choose Our 4340 Steel
Quality Assurance
Materials sourced directly from government-owned steel mills with ISO 9001 certified quality management system.
Materials sourced directly from government-owned steel mills with ISO 9001 certified quality management system.
Timely Delivery
Speedy processing and delivery for both raw materials and finished products with machining or heat treatment.
Speedy processing and delivery for both raw materials and finished products with machining or heat treatment.
Comprehensive Services
Value-adding services including metal cutting, sizing, machining, heat treatment, and sawing for any quantity.
Value-adding services including metal cutting, sizing, machining, heat treatment, and sawing for any quantity.
Extensive Inventory
Unique inventory of specialty steel with orders of any size or length accommodated.
Unique inventory of specialty steel with orders of any size or length accommodated.
Additional Product Images

