ASTM A193 grade B7M includes chromium-molybdenum alloy steel fasteners covered in this basic material specification. These high-tensile fasteners are in high demand in chemical and petroleum construction applications. They are made
by quenching and tempering in the heat to attempt the necessary hardness and mechanical properties. The bolting solutions are mainly implemented in extensive pressure and temperature-related services like fittings, pressure valves,
flanges, and valves. The distinction between B7M and B7 is the testing necessary for hardness in every fastener.
A193 Grade B7M
| B7M |
Alloy steel, AISI 4140/4142 quenched and tempered |
Mechanical properties
| Size |
Tensile ksi, min |
Yield ksi, min |
Elong %, min |
RA % min |
HBW |
Rockwell |
| Up to 4 |
100 |
80 |
18 |
50 |
235 Max |
- |
| Over 4 - 7 |
100 |
75 |
18 |
50 |
Chemical properties
| Element |
B7 (AISI 4140) |
| Carbon |
0.37 - 0.49% |
| Manganese |
0.65 - 1.00% |
| Phosphorus, max |
0.035% |
| Sulfur, max |
0.040% |
| Silicon |
0.15 - 0.35% |
| Chromium |
0.80 - 1.10% |
| Nickel |
- |
| Molybdenum |
0.15 - 0.25% |
Compatible hardware
| Bolt Grade |
Nut |
Washers |
| B7M |
A194 Grade 2HM |
F436 |
