Introduction to Grade 10.9 Bolt Hardness
In fact, a 10.9 grade bolt is one of the common names for flat head hexagonal bolts. When the bolt reaches 8.8 grade, it is actually a watershed for bolts. Bolts below 8.8 grade can be called ordinary bolts, while those above 8.8 grade can be called high-strength bolts. Today, let me briefly introduce to you about the hardness of 10.9 grade bolts!
Construction technology:
Process 1:
After hot forging and forming, the machine is processed using a mesh belt furnace for heat treatment. The quenching temperatures (zones 1-4) are (860-870-870-860), and the quenching time is about 90 minutes. The quenching oil is cooled, and the hardness after quenching is HRC49-52; The tempering temperature (zones 1-3) is 510, and the hardness after tempering is HRC32-35. After inspection, the tensile strength is about 1030 MPa, but it cannot meet the performance requirements.
Process 2:
Annealing phosphating cold extrusion forming, heat treatment using a mesh belt furnace, quenching temperatures (zones 1-4) of (860-870-870-860), quenching time of about 90 minutes, quenching oil cooling, hardness after quenching is HRC49-52; One tempering temperature (zones 1-3) is 480, and the hardness after tempering is HRC34-38, with a tensile strength of 1005MPa after inspection. The other tempering temperature (zones 1-3) is 460, and the hardness after tempering is HRC36-40, with a tensile strength of 960MPa after inspection, and there is a small amount of ferrite present.
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