BOLT GRADES, STRENGTH AND MARKINGS

Bolt grades, strength and grade markings for steel bolts as designated by ASTM and SAE.

Bolt Strength Chart
Bolt Grade Markings	Bolt Grades	Bolt Material	Bolt Size (in)	Min. Bolt Strength (10^3 psi)
				Proof	Tensile	Yield
	SAE Grade 1	Low or medium carbon	1/4 to 3/2	33	60	36
	ASTM A307	Low carbon	1/4 to 3/2	33	60	36
	SAE Grade 2	Low or medium carbon	1/4 to 3/4	55	74	57
			7/8 to 3/2	33	60	36
	SAE Grade 4	Medium carbon, cold drawn	1/4 to 3/2	65	115	100
	SAE Grade 5	Medium carbon, quench and temper	1/4 to 1	85	120	92
	ASTM A449		9/8 to 3/2	74	105	81
	ASTM A449		7/4 to 3	55	90	58
	SAE Grade 5.2	Low-carbon martensite, quench and temper	1/4 to 1	85	120	92
	ASTM A325, Type 1	Medium carbon, quench and temper	1/2 to 1	85	120	92
			9/8 to 3/2	74	105	81
	ASTM A325, Type 2	Low-carbon martensite, quench and temper	1/2 to 1	85	120	92
			9/8 to 3/2	74	105	81
	ASTM A325, Type 3	Weathering steel, quench and temper	1/2 to 1	85	120	92
			9/8 to 3/2	74	105	81
	ASTM A354, Grade BC	Weathering steel, quench and temper	1/4 to 5/2	105	125	109
			11/4 to 4	95	115
	SAE Grade 7	Medium-carbon alloy, quench and temper	1/4 to 3/2	105	133	115
	SAE Grade 8	Medium-carbon alloy, quench and temper	1/4 to 3/2	120	150	130
	ASTM A354, Grade BD	Alloy steel, quench and temper	1/4 to 3/2	120	150	130
	SAE Grade 8.2	Low-carbon martensite, quench and temper	1/4 to 1	120	150	130
	ASTM A490, Type 1	Alloy steel, quench and temper	1/2 to 3/2	120	150	130
	ASTM A490, Type 3	Weathering steel, quench and temper

Note: Minimum strengths are strengths exceeded by 99 percent of fasteners.

Supplements:

• Thread Calculators and Charts

Reference:

• Oberg.E , Jones.D.J., Holbrook L.H, Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc. , pp 1521 - 1537
• Budynas.R , Nisbett.K. (2008) . Shigley's Mechanical Engineering Design . 8th edition.  McGraw-Hill