ASTM A320 Gr B8M Studs, Grade B8M Bolts, ASTM A320 Grade B8M Stud Bolt, ASTM A320 Grade B8M Threaded Rod Suplier in Mumbai, India.
Standard Specification for Alloy-Steel and Stainless Steel Bolting for Low-Temperature Service
ASTM A320 Grade 8M Class 1 fasteners are similar to Grade B8 but instead are manufactured from AISI 316 stainless steel as opposed to AISI 304 stainless steel. Although more expensive, type 316 stainless offers superior corrosion resistance compared to type 304 stainless. Grade B8M Class 1 fasteners require carbide solution treatment, while Class 2 fasteners require an additional strain hardening operation. A320 Grade B8M bolts also do not require an impact test.
Bolting A320 Grade B8M
| B8M Class 1 Stainless steel |
AISI 316, carbide solution treated |
| B8M Class 2 Stainless steel |
AISI 316, carbide solution treated, strain hardened |
ASTM A320 Grade B8M Chemical Composition
| Element |
B8M (AISI 316) |
| Carbon |
0.08% max |
| Manganese |
2.00% max |
| Phosphorus, max |
0.045% |
| Sulfur, max |
0.030% |
| Silicon |
1.00% max |
| Chromium |
16.0 - 18.0% |
| Nickel |
10.0 - 14.0% |
| Molybdenum |
2.00 - 3.00% |
ASTM A320 Grade B8M Mechanical Properties
| Grade |
Diameter |
Tensile, ksi, min |
Yield, ksi, min |
Charpy Impact 20-ft-lbf @ temp |
Elong, %, min |
RA, %, min |
| Class 1: B8M |
All |
75 |
30 |
N/A |
30 |
50 |
| Class 2: B8M |
Up to 3⁄4 |
110 |
95 |
N/A |
15 |
45 |
| 7⁄8 - 1 |
100 |
80 |
N/A |
20 |
45 |
| 11⁄8 - 11⁄4 |
95 |
65 |
N/A |
25 |
45 |
| 13⁄8 - 11⁄2 |
90 |
50 |
N/A |
30 |
45 |
A320 Grade B8M Recommended Hardware
| Grade |
Nuts |
Washers |
| B8M Class 1 |
A194 Grade 8M |
SS316 |
| B8M Class 2 |
A194 Grade 8M |
SS316 |