Difference between ASTM A193 B7 and ASTM A193 B8M Bolts
Feature ASTM A193 B7 ASTM A193 B8M
Material Alloy Steel Stainless Steel (316)
Common Alloy Chromium-Molybdenum Steel Type 316 Stainless Steel (with Mo)
Magnetic? Yes Typically non-magnetic
Corrosion Resistance Low to Moderate High
Heat Treatment Quenched and tempered Cold worked Tensile Strength 860 MPa 515 MPa
Temperature Suitability Up to ~450°C Good for both high and low temps
Corrosion Resistance
Environment A193 B7 A193 B8M
Atmospheric (mild) Acceptable with coating Excellent Marine (saltwater) Not suitable Highly suitable (due to Mo content)
Chemical (acidic/basic) Poor Excellent (especially vs chlorides)
