ASTM A193 Grade B6 bolts and threaded rods are manufactured from AISI 410 stainless steel which has been quenched and tempered to increase strength. Because these bolts are manufactured from stainless steel, they are used in highly corrosive environments with elevated ambient temperatures.
Grade B7 is a heat-treated chromium-molybdenum alloy steel with minimum tensile requirement of 100 ksi, yield of 75 ksi and maximum hardness of 35 HRC. ASTM A193 specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment, recommended nuts-washers for Grade B7 fasteners.
The ASTM standard covers alloy steel and stainless steel bolting materials for high temperature or high-pressure service....A193 Grades.
It is also quenched and tempered at 800 F leading to its strength. Grade 8 has 0.
Grade 5
Class 10.
Commercial-grade 8 bolts are the strongest option available. They're made from medium carbon alloy steel and have markings that include six raised dashes. The psi of the bolt is 150,000, meaning that it can withstand great deals of pressure because of the way it was quenched and tempered.
Grade 8 bolts have been hardened more than grade 5 bolts. Thus they are stronger and are used in demanding applications such as automotive suspensions. Grade 8 bolts have 6 evenly spaced radial lines on the head. Grade G is roughly equivalent to Grade 8.
Stronger bolts are often harder and so tend to be more brittle. Rather than stretch as required for situations the equipment's manufacturer had selected the original bolt to meet, the higher grade fastener snaps off.
Stainless commonly comes in grades 18.
The grade 8 will have a higher tensile strength but it's more brittle and will snap before it bends.
Grade 9 bolts are ideal for heavy-duty applications and are also often used in heavy machinery such as bulldozers. Not only are these bolts considerably stronger than they're grade 8 counterparts, but they are also considerably more resistant to corrosive elements as they are made with yellow zinc chromate.
12.
Approximate Equivalency Chart Metric/US Roughly Equivalent US Bolt Materials