China Manufacturer of ASTM A320 L7M Stud Bolt Metric Threaded ISO DIN 13 -6g
What is Stud Bolt Metric Threaded?
Stud bolt is a round rod with thread on full or partially.It is an important parts for flange,valves.
there are Imperial thread and metric thread for the stud bolts.
Metric bolt sizes are manufactured according to strict metric thread dimensions and specifications defined by the ISO standardisation authority to ensure cross-compatibility between mating components. The metric thread size chart below represents the dimensions of metric coarse machine screw threads as defined by ISO standards.
About ISO DIN 13
ISO DIN-13 refers to a German standard related to the design and dimensions of metric threads, particularly for bolts and screws. This standard specifies the geometry, tolerances, and designations of thread profiles and is commonly used in mechanical engineering.
Standardized thread that replaces the old metric and most inch threads. It is designated by the letter M (metric), followed by a number indicating the nominal diameter, the angle of inclination of the profile is 60°.
ASTM A320 L7M Stud Bolt metric thread specification
1. Material and Grade:
- Material: Low-alloy steel with added chromium and molybdenum for strength and toughness at low temperatures.
- Grade L7M:
- A modification of Grade L7, tailored for environments requiring additional resistance to sulfide stress cracking and hydrogen embrittlement.
2. Mechanical Properties:
- Tensile Strength: Minimum 105 ksi (724 MPa).
- Yield Strength: Minimum 75 ksi (517 MPa).
- Elongation: Minimum 20% (measured on a standard 2-inch gauge length).
- Reduction of Area: Minimum 50%.
- Charpy Impact Test:
- Ensures performance at low temperatures, typically down to -150°F (-101°C).
3. Heat Treatment:
- Bolts must be quenched and tempered to achieve the required mechanical properties and toughness.
- Tempering reduces brittleness and improves toughness for low-temperature applications.
4. Chemical Composition:
Typical composition includes:
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.37 max |
| Manganese (Mn) | 0.65–1.10 |
| Phosphorus (P) | 0.035 max |
| Sulfur (S) | 0.040 max |
| Silicon (Si) | 0.15–0.35 |
| Chromium (Cr) | 0.75–1.20 |
| Molybdenum (Mo) | 0.15–0.25 |
| Vanadium (V) | 0.03 max |
Metric Thread Specification
For stud bolts under ASTM A320 L7M with metric threads, the specifications are typically aligned with international thread standards such as DIN 13 or similar standards could also be referenced.
Thread Parameters
- Thread Profile: Metric threads per DIN 13
- Tolerances:
- Internal threads: Tolerance class 6H
- External threads: Tolerance class 6g.
- Thread Length: Defined per design or application; DIN 976 or ASME B18.31.2 might provide guidelines for stud bolt lengths.
- Pitch Diameter: Specific to thread size and pitch (refer to tables in standards like ISO 965-1 for values).6. Coating and Finishes:
Surface Treatement for ASTM A320 L7M Stud Bolt
Hot-Dip Galvanizing (HDG) is often applied for enhanced corrosion resistance in harsh environments.
PTFE Xylan Coating:Xylan 1070,Xylan 1424 coating.
