ASTM A320 GRADE L7M – MTC
ASTM A320 Grade L7M Sample MTC Certificate
Access a comprehensive, professionally formatted Material Test Certificate according to EN 10204-2004: 3.1 for ASTM A320 Grade L7M. Review the rigorous documentation verifying this alloy steel's modified tempering, 100% hardness testing compliance for sour gas (H2S) service, and low-temperature Charpy impact performance.
What's Inside This A320 L7M MTC Certificate
This sample mill test certificate emphasizes the critical testing parameters required for ASTM A320 Grade L7M—a Chromium-Molybdenum alloy steel specifically modified ("M") with a controlled maximum hardness to resist Sulfide Stress Cracking (SSC) in oil and gas environments.
- Full Traceability: Certified with TC No.: S134/26-XX and fully mapped to ASTM A320 low-temperature bolting specifications.
- 100% Hardness Testing: Explicit confirmation that every individual fastener in the lot was hardness tested and found to be under the strict maximum limit of 235 HBW (99 HRB), a mandatory requirement for Grade L7M.
- Modified Heat Treatment: Verification that the material was quenched and tempered at a higher minimum temperature of 1150°F (620°C) to effectively lower the hardness and tensile strength for NACE compliance.
- Charpy V-Notch Impact Testing: Logs passing impact test energy values at the specified low temperature of -100°F (-73°C), ensuring the material retains necessary toughness.
- Mechanical Performance: Detailed logs of Tensile Strength (Min 690 MPa / 100 ksi), Yield Strength (Min 550 MPa / 80 ksi), and Elongation (Min 18%).
Live Preview: ASTM A320 Grade L7M MTC Data
Review the standard parameters and layout before downloading the full document.
TC Number
S134/26-XX
TC Date
14.01.20XX
Material Spec
ASTM A320 GRADE L7M (Alloy Steel)
Bar Shape / Size
Round Bar / 24 mm
Dimensions / Item
Heavy Hex Bolt M24-3P x 150 mm
Quantity
150.00 NOS
Chemical Composition % (AISI 4140 Typical)
| C | Mn | P | S | Si | Cr | Mo |
|---|---|---|---|---|---|---|
| 0.41 | 0.85 | 0.015 | 0.012 | 0.25 | 0.95 | 0.20 |
| Min: 0.38 Max: 0.48 |
Min: 0.75 Max: 1.00 |
Max: 0.035 | Max: 0.040 | Min: 0.15 Max: 0.35 |
Min: 0.80 Max: 1.10 |
Min: 0.15 Max: 0.25 |
Mechanical & Impact Properties
| TENSILE STRENGTH (MPa) | YIELD STRENGTH 0.2% Offset (MPa) | % ELONGATION (GL-50mm) | HARDNESS (HBW) | IMPACT ENERGY @ -73°C (Joules) |
|---|---|---|---|---|
| 740.50 | 610.20 | 22.00 | 215, 218, 220 | 45, 48, 42 |
| Min: 690 (100 ksi) | Min: 550 (80 ksi) | Min: 18 | Max: 235 | Min: 27 (20 ft-lbf) @ -100°F |
Standard References & Compliance
Our MTC certificates comprehensively align with the demanding specifications of the petrochemical sector, particularly for sour gas applications. The test reports confirm exact compliance with ASME/ASTM A320 / A320M and NACE MR0175 with respect to the specific heat and lot tested.
| Standard / Requirement | Confirmation on Certificate |
|---|---|
| Hardness Testing (100%) | 100% hardness tested. All pieces conform to 235 HBW maximum. |
| Charpy V-Notch Impact Test | Tested at -100°F (-73°C). Results meet minimum 20 ft-lbf requirement. |
| Sour Service Suitability | Material complies with metallurgical requirements of NACE MR0175 / ISO 15156. |
| Dimensional Accuracy | All Dimensions are as per PO Specification / ASME B18.2.1. |
Certification Details
We confirm that the above mentioned items were Manufactured, Sampled, Tested, and Inspected in accordance with the subjected Customer's Purchase Order and applicable Drawings, Material Specifications, Codes & Standards.
Documentation Standard
- EN 10204-2004: 3.1 Standard
- Free from radioactive contamination
- Certified ISO 9001: 2015 Company
Heat Treatments
- Quenched & Tempered
- Min Tempering Temp: 1150°F (620°C)
Testing Conditions
- 100% of pieces Hardness Tested
- Charpy Impact Test at -100°F (-73°C)
Technical FAQs — ASTM A320 Grade L7M MTC
What is the difference between Grade L7 and Grade L7M?
The "M" stands for modified. While both use the same base alloy (usually AISI 4140), Grade L7M is tempered at a higher temperature (1150°F minimum compared to 1100°F for L7). This modified heat treatment intentionally lowers the tensile and yield strength, ensuring the maximum hardness does not exceed 235 HBW. This specific lower hardness is required to prevent Sulfide Stress Cracking (SSC) in sour gas environments.
Why is 100% Hardness Testing required on this MTC?
In sour gas (H2S) environments, any fastener that is too hard is at extreme risk of catastrophic hydrogen embrittlement and cracking. Because of this severe safety risk, the ASTM A320 specification mandates that every single Grade L7M bolt in a production lot must be individually hardness tested to guarantee none exceed the 235 HBW limit. The MTC confirms this procedure was completed.
What does NACE MR0175 compliance mean for L7M?
NACE MR0175 (now also ISO 15156) is a global standard for materials used in H2S-containing environments in oil and gas production. By restricting the hardness of Grade L7M to 235 HBW maximum, the material complies with the metallurgical requirements established by NACE to safely resist stress corrosion cracking in these highly corrosive environments.