4140 Alloy Steel Precision Ground Bar
4140 Round Bar: 8mm – 3000mm Diameter
4140 Plate: 10mm – 1500mm Thickness x 200mm – 3000mm Width
4140 Square Bar: 20mm – 500mm Diameter
Surface Treatment: Blackened, Rough Cut, Turned or as per customer’s requirement.
As a leading supplier and manufacturer in China, GNEE Steel provides cost-effective nickel-based alloy products.
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GNEE 4140 Steel Precision Ground Bar introduce
4140 Alloy Precision Ground Bar
4140 Precision Ground Bar is a high-strength chromium-molybdenum alloy steel bar manufactured by cold drawing and centerless grinding. With a dimensional tolerance of ±0.013mm and a surface roughness of Ra≤0.4μm, it is an ideal choice for core components of precision machinery. Its core performance characteristics include:
Three core advantages
Ultimate strength and wear resistance
After quenching and tempering heat treatment (Q&T), the hardness reaches HRC 28-32, the tensile strength ≥950 MPa, the yield strength ≥850 MPa, and the wear resistance is more than 3 times that of ordinary 45# steel, especially suitable for high-frequency friction scenarios (such as injection mold guides, hydraulic valve cores).
Microstructure homogeneity
Precision grinding eliminates surface microcracks and decarburization layers, and the fatigue life is increased by 40-60% compared with ordinary hot-rolled bars (10⁷ cycles of stress>450 MPa).
Zero processing, ready to use
Diameter tolerance is controlled to h6/h7 level (such as ∅25mm rod tolerance ±0.013mm), straightness ≤0.3mm/m, eliminating turning/grinding processes, reducing processing costs by 30%.
GNEE 4140 Alloy Steel Precision Bar Specification
AISI 4140 Precision Ground Bar: Comprehensive Property Table
|
Property Category |
Parameter/Specification |
Technical Details |
|---|---|---|
|
Basic Dimensions |
Diameter Range (mm) |
3.0 - 150.0 (±0.003mm) |
|
Length Range (m) |
0.5 - 8.0 (Straightness ≤0.01mm/m) |
|
|
Geometric Precision |
Dimensional Tolerance |
h5 Grade (e.g., φ20h5 = +0/-0.013mm) |
|
Roundness Tolerance |
≤ 0.0015mm |
|
|
Cylindricity Tolerance |
≤ 0.002mm/m |
|
|
Surface Properties |
Surface Roughness (Ra) |
0.1 - 0.4 μm (Mirror Finish) |
|
Processing Method |
Centerless Grinding → Superfinishing → Electrolytic Polishing |
|
|
Physical Properties |
Density |
7.85 g/cm³ (±0.01) |
|
Hardness Range |
30-35 HRC (Q&T) / 50-55 HRC (Nitrided Surface) |
|
|
Material Certification |
Chemical Composition (%) |
C:0.38-0.43, Cr:0.90-1.20, Mo:0.18-0.25, Mn:0.70-0.90, Si:0.15-0.35 |
|
Purity |
Inclusions ≤0.5 Level (ASTM E45) / Oxygen Content ≤15ppm |
|
|
Core Standards |
International Norms |
ISO 683-18 Gr.E / ASTM A108-19 / EN 10083-3 |
|
Special Treatments |
Enhanced Processes |
Cryogenic Treatment (-196°C×2h) + Stress Relief (300°C×3h) |
Mechanical Properties Comparison
|
Mechanical Property |
Precision Ground State |
Ground + Nitrided |
Technical Advantage |
|---|---|---|---|
|
Tensile Strength (MPa) |
1050 - 1250 |
1100 - 1300 |
↑15% vs Standard Bars |
|
Yield Strength (MPa) |
≥ 850 |
≥ 950 |
↑20% Deformation Resistance |
|
Fatigue Limit (MPa) |
≥ 450 |
≥ 500 |
>10⁷ Cycles @ 400 MPa |
|
Impact Toughness (J) |
25 - 35 |
20 - 30 |
Maintains Safety Threshold |
4140 Steel Bar Chemical Composition
| Standard | Grade | C | Mn | P | S | Si | Cr | Mo |
| ASTM A29 | 4140 | 0.38-0.43 | 0.75-1.00 | 0.035 | 0.040 | 0.15-0.35 | 0.8-1.10 | 0.15-0.25 |
| EN 10083/EN 10250 | 42CrMo4/1.7225 | 0.38-0.45 | 0.6-0.9 | 0.035 | 0.035 | 0.4 | 0.9-1.2 | 0.15-0.30 |
| JIS G4105 | SCM440 | 0.38-0.43 | 0.60-0.85 | 0.03 | 0.03 | 0.15-0.35 | 0.9-1.2 | 0.15-0.30 |
GNEE 4140 Alloy Steel Ground Bar Schedule
AISI 4140 Precision Ground Bar: Market Standard Sizes
|
Diameter (mm) |
Tolerance Class |
Standard Length (m) |
Stock Ratio (%) |
Base Price (USD/m) |
MOQ |
|---|---|---|---|---|---|
|
3.0 - 6.0 |
h4 (±0.002) |
0.5 - 1.5 |
15% |
$25 - $50 |
30 kg |
|
6.1 - 12.0 |
h5 (±0.004) |
1.0 - 3.0 |
45% |
$50 - $120 |
20 kg |
|
12.1 - 25.0 |
h5 (±0.006) |
1.5 - 4.0 |
70% |
$120 - $300 |
15 kg |
|
25.1 - 50.0 |
h6 (±0.01) |
2.0 - 6.0 |
60% |
$300 - $800 |
10 kg |
|
50.1 - 80.0 |
h6 (±0.015) |
3.0 - 8.0 |
40% |
$800 - $2,200 |
8 kg |
|
80.1 - 120.0 |
h7 (±0.02) |
4.0 - 10.0 |
25% |
$2,200 - $5,500 |
5 kg |
GNEE Group Factory Environment
GNEE Group 4140 Precision Ground Bar Factory Environment
GNEE Group 4140 Steel Precision Bar Packaging
GNEE Group 4140 Alloy Precision Bar Packaging
GNEE Group Testing
GNEE Group 4140 Precision Ground Bar Testing
FAQ
Is 4140 alloy steel corrosion resistant?
Although 4140 steel contains chromium to improve corrosion resistance, it is not highly resistant to corrosion. Appropriate coatings or protective measures are recommended for use in corrosive environments.
What is the difference between 4140 and 4340 alloy steels?
4140 steel has a lower carbon content than 4340 steel, making it easier to machine. However, 4340 steel has higher strength and toughness, especially in larger sections, and is often used in heavy-duty applications.
Can 4140 alloy steel be welded?
Yes, 4140 steel can be welded using the proper welding techniques and precautions. However, post-weld heat treatment may be required to restore its properties, especially in the heat-affected zone.
What is the maximum hardness that 4140 steel can achieve through heat treatment?
Depending on the specific heat treatment process, 4140 steel can reach a hardness of up to approximately 58-60 HRC.
Is 4140 alloy steel round bar available in a variety of sizes and shapes?
Yes, 4140 Alloy Steel Round Bar is available in a variety of sizes and can also be made into a variety of shapes including square bars and flat bars to suit a variety of applications.
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