BOLT GRADES, STRENGTH AND MARKINGS

Bolt grades, strength and bolt 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