Grade A193-B8

ASTM A193 Grade B8 Class 1 bolts are made from 304 stainless steel which is the most common grade of stainless steel used. This is austenitic stainless steel and requires a carbide solution treatment on bars to be threaded or after the heading operation for bolts with forged heads.  A193 Grade B8 Class 2 bolts are strain hardened after carbide solution treatment to achieve increased strength characteristics. Class 2 bolts are marked “B8SH” with the grade symbol underlined. 

Grade Size Tensile ksi, min Yield, ksi, min Elong, %, min RA % min HBW Rockwell 
B8 Class 1 All 75 30 30 50 223 max 96 max HRB 
B8 Class 2 Up to 3/4 125 100 12 35 321 max 35 max HRC 
7/8 – 1 115 80 15 35 
1-1/8 – 1-1/4 105 65 20 35 
1-3/8 – 1-1/2 100 50 28 45 

ASTM A193 Grade B8M Class 1

The only difference between these fasteners and A192-B8 fasteners is that this grade is made from 316 stainless steel which has superior corrosion resistance properties. Class 2 fasteners are marked “B8MSH” with the grade symbol underlined.

Grade A193-B7M

ASTM A193 Grade B7M bolts and studs are identical in chemistry to Grade B7 but has lower strength requirements and require 100% hardness testing.

Grade Diameter Tensile ksi, min Yield, ksi, min Elong, %, min RA % min HBW HRC 
B7 Up to 4 100 80 18 50 235 max – 
Over 4 – 7 100 75 18 50 

Grade A193-B16

ASTM A193 Grade B16 bolts are manufactured from a chromium-molybdenum-vanadium alloy steel. This grade is very similar to grade B7 bolts except they can endure higher temperatures while retaining a higher strength.

Grade Diameter Tensile ksi, min Yield, ksi, min Elong, %, min RA % min HBW HRC 
B16 Up to 2-1/2 125 105 18 50 321 max 35 max 
Over 2-1/2 to 4 110 95 17 45 
Over 4 to 8 100 85 16 45 

Grade A193-B5

ASTM A193 Grade B5 bolts are manufactured from AISI 501 stainless steel which has been quenched and tempered to increase strength. These are used in high temperature and highly corrosive environments. 

Grade Diameter Tensile ksi, min Yield, ksi, min Elong, %, min RA % min HBW HRC 
B5 Up to 4, incl 100 80 16 50 – – 

Grade A193-B6

ASTM A193 Grade B6 bolts are manufactured from AISI. They are used in highly corrosive environments with elevated ambient temperatures. 

Grade Diameter Tensile ksi, min Yield, ksi, min Elong, %, min RA % min HBW HRC 
B6 Up to 4, incl 110 85 15 50 – – 
B6X 90 70 16