A194 Grade 8m Steel Bolts

• Material: Stainless,Carbon,Alloy
• Type: Hexagon Head
• Connection: Hinged Bolts
• Head Style: Hexagonal
• Standard: DIN, ANSI
• Grade: B7, B8, B8m,2h,2hm,etc
• Model NO.: KM-20201126
• Finish: Black,Galvanized,Pfte Coated
• Certificate: ISO, CE
• Color: Blue, Black, Zinic White, Yellow Zinc
• Thread: Unc
• Thread Type: Full, Half
• Transport Package: in Sea Worthy Export Packing
• Specification: 1/2" to 4"
• Trademark: Kingmetal
• Origin: China
• HS Code: 7616100000
• Production Capacity: 1000 Tons Per Month

Product Description

A194 Grade 8M Steel bolts
 

There are several grades within the A193 specification. Each grade possesses unique chemical requirements, strength requirements, testing requirements, and applications. This website summarizes the similarities and differences between many of the grades. For more specific information, please refer to the actual ASTM A193 specification which can be purchased directly from ASTM International.

Bolt Grade	Nuts	Washers
B7	A194 Grade 2H	F436
B8 Class 1	A194 Grade 8	SS304
B8M Class 1	A194 Grade 8M	SS316
B8 Class 2	A194 Grade 8	SS304
B8M Class 2	A194 Grade 8M	SS316

A194 Chemical Properties

Element	2, 2H, and 2HM	4	7 and 7M (AISI 4140)	8 (AISI 304)	8M (AISI 316)
Carbon	0.40% min	0.40 - 0.50%	0.37 - 0.49%	0.08% max	0.08% max
Manganese	1.00% max	0.70 - 0.90%	0.65 - 1.10%	2.00% max	2.00% max
Phosphorus, max	0.040%	0.035%	0.035%	0.045%	0.045%
Sulfur, max	0.050%	0.040%	0.040%	0.030%	0.030%
Silicon	0.40% max	0.15 - 0.35%	0.15 - 0.35%	1.00% max	1.00% max
Chromium			0.75 - 1.20%	18.0 - 20.0%	16.0 - 18.0%
Nickel				8.0 - 11.0%	10.0 - 14.0%
Molybdenum		0.20 - 0.30%	0.15 - 0.25%		2.00 - 3.00%

Grade B7

ASTM A193 Grade B7 bolts and threaded studs are manufactured from a chromium-molybdenum steel and are quenched and tempered (heat treated) to develop the desired mechanical properties (strength). Grade B7 is the most common grade of A193 bolts used in construction. B7 threaded studs and short, headed bolts are readily available in the marketplace. Grade B7 bolts are commonly used in pipe flange connections. These bolts are typically bought and sold in a plain, bare metal finish but are often hot-dip galvanized, zinc plated, Xylan coated, PTFE coated, or otherwise coated for corrosion resistance. Note that coated bolts may not be able to withstand the high temperatures that uncoated B7 bolts can be subjected to.

Grade	Size	Tensile ksi, min	Yield, ksi, min	Elong, %, min	RA % min	HBW	HRC
B7	Up to 2-1/2	125	105	16	50	321 max	35 max
	2-5/8 - 4	115	95	16	50
	4-1/8 - 7	100	75	18	50

Grade B8

ASTM A193 Grade B8 Class 1 bolts and threaded studs are manufactured from AISI 304 stainless steel. Type 304 is the most common grade of stainless steel used in the fastener industry. Fasteners manufactured using this austenitic stainless steel require carbide solution treatment on bars to be threaded or after the heading operation for bolts with forged heads.  Carbide solution treatment, also referred to as solution annealing, is a process in which fasteners or stainless bars are heated and then water-quenched to assure maximum corrosion resistance.  A193 Grade B8 Class 2 bolts are strain hardened after carbide solution treatment to achieve increased strength characteristics and reduce the potential for galling. Class 2 bolts are marked "B8SH" with the grade symbol underlined.

Grade	Size	Tensile ksi, min	Yield, ksi, min	Elong, %, min	RA % min	HBW	HRC
B8 Class 1	All	75	30	30	50	223 max	96 max
B8 Class 2	Up to 3/4	125	100	12	35	321 max	35 max
	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

Grade B8M

ASTM A193 Grade B8M Class 1 fasteners are similar to Grade B8 but instead are manufactured from AISI 316 stainless steel as opposed to AISI 304 stainless steel. Type 316 stainless offers superior corrosion resistance to type 304 stainless due to the added molybdenum. Grade B8M Class 1 fasteners require carbide solution treatment, while Class 2 fasteners require an additional strain hardening operation which increases the strength and reduces the susceptibility to galling. Class 2 fasteners are marked "B8MSH" with the grade symbol underlined.

Grade	Size	Tensile ksi, min	Yield, ksi, min	Elong, %, min	RA % min	HBW	HRC
B8M Class 1	All	75	30	30	50	223 max	96 max
B8M Class 2	Up to 3/4	110	95	15	45	321 max	35 max
	7/8 - 1	100	80	20	45
	1-1/8 - 1-1/4	95	65	25	45
	1-3/8 - 1-1/2	90	50	30	45

Grade B7M

ASTM A193 Grade B7M bolts and studs are identical in chemistry to Grade B7 (quenched and tempered medium carbon alloy steel), but have lower strength requirements and require 100% hardness testing of all fasteners manufactured in the lot. Grade B7M bolts resist chloride, sulfide, and hydrogen stress corrosion cracking (SCC) and are frequently used in sour gas service.

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 Variations

Grade variations of the A193 specification which are rarely used and therefore not addressed on this site include: B6X, B8A, B8C, B8CA, B8MA, B8M2, B8M3, B8P, B8PA, B8N, B8NA, B8MN, B8MNA, B8MLCuN, B8MLCuNA, B8r, B8RA, B8S, B8SA, B8LN, B8LNA, B8MLN, B8MLNA, B8CLN, B8CLNA, B8T, and B8TA.