ASTM A193 Grade B8M Class 2 Stud Bolts

ASTM A193 Grade B8M Class 2 Stud Bolts

Lightning Bolt is an ISO 9001 certified fastener manufacturer for ASTM A193 Grade B8M Class 2 Stud Bolts.  In addition to many different sizes and grades of ASTM A193 Grade B8 Stud Bolts, we also carry one of the largest inventories of ASTM A194 Grade 8 & 8M stainless heavy hex nuts in North America.   Very commonly used in the assembly of industrial pipe & valves, the chemical composition of ASTM A193 Grade B8M Class 2 Stud Bolts are considered nearly identical to grade 316 stainless steel, hover they are also strain hardened.  Email us your inquiries at

Many of our customers may understand that ASTM A193/A193M is a specification that covers both inch and metric series carbon alloy steel and stainless steel bolting materials.  This includes externally threaded bolts, screws, and studs.  It is intended to cover alloy and stainless steel bolting material for pressure vessels, valves, flanges, and fittings for high temperature service.  Bars and wire shall be hot-wrought, and the material may be further processed by center less grinding or by cold drawing.  Austentic stainless steel, which is a 300 series stainless, has austenite, which is a a metallic, non-magnetic, allotrope of iron as its primary phase.  Such alloys contain chromium, nickel (and sometimes nitrogen and molybdenum) & although they can not be thru hardened, they can be carbide solution treated or carbide solution treated & strain-hardened (which is considered “class2”).

Heat treated conditions for the ferritic materials include:

  • normalized & tempered
  • quenched & tempered.

Heat treated conditions for the austentic stainless steels include:

  • Carbide solution treated (Class 1)
  • Carbide solution treated after finishing (Class 1A)
  • Carbide solution treated nitrogen-bearing stainless steels (Class 1B & 1C)
  • Carbide solution treated by cooling rapidly from the rolling temperature (Class 1D)
  • Carbide solution treated and Strain-hardened (Classes 2, 2B, and 2C)

All austentic stainless steels shall receive a carbide solution treatment which applies to each class.  Class 1, 1B, and 1C (Grades B8R and B8S only), 2, 2B, and 2C can apply to bar, wire, and finished fasteners.  Class 1A (ALL GRADES) and Class 1C (GRADES B8RA & B8SA only) can apply to finished fasteners as well.  Class 1D applies only to bar and wire and finished fasteners that are machined directly from class 1D bar or wire without any subsequent hot or cold working.  Finished products must conform to ASTM Chemical composition and Mechanical Properties tables (listed below).

Class 2 materials shall be carbide solution treated by heating for the ambient temperature and holding at a sufficient time at a temperature at which the chromium carbide will go into solution and then cooling at a rate sufficient to prevent the precipitation of the carbide. Stain-hardening of austentic steels is the increase in strength and hardness that results from plastic deformation below the re crystallization temperature (cold work).  This effect is produces in austentic stainless steels by reducing oversized bars or wire to the desired final size by cold drawing or other process.  The degree of strain-hardening achievable in any alloy is limited by its strain-hardening characteristics.  In addition, the amount of strain-hardening that can be produced is further limited by the variables of the process, such as the total amount of cross section reduction, die angle, and bar size.  In large diameter bars, for example, plastic deformation will occur principally in the outer regions of the bar so the the increased strength and hardness due to strain-hardening is achieved predominantly near the surface of the bar.  Therefore, the smaller the bar, the greater the penetration of the strain-hardening.

Why Lightning Bolt ASTM A193 Grade B8M Class 2 Stud Bolts?

Lightning Bolt & Supply has been servicing North America’s industrial fastener needs for over 25 years.  Since then, our focus on the production of high quality parts at competitive pricing has allowed us to become an industry leader.  Our niche in exotic high nickel alloy fasteners include materials such as: hastelloy, Inconel, monel, A-286, 904L, Alloy-20, duplex stainless as well as many additional alloys.

Being centrally headquartered in Baton Rouge, Louisiana, we are capable of shipping to jobsites all over the world.  Many of our industrial projects that we supply material to include anchor bolts, and also stud bolts of many different ASTM grades.  These include B7, L7, B16, B8, B8M, stain hardened and many more.  In addition to being an ISO certified fastener manufacturer, we were awarded “Corporate Supplier of the Year” by WBENC.


ASTM A193 B8M, B8MA, B8M2, B8M3, B8P, B8PA

IdentificationB8M, B8MA, B8M2, B8M3 B8P, B8PA 
Grade18 Chromium- 10 Nickel- 2 Molybdenum (Type 316 Stainless)Unstabilized 18 Chromium - 8 Nickel (Type 305 Nickel)



Tolerance +/-


Tolerance +/-

Carbon, max0.080.01 over0.120.01 over
Manganese, max2.000.04 over2.000.04 over
Phosphorus, max0.0450.010 over0.0450.010 over
Sulfur, max0.0300.005 over0.0300.005 over
Silicon1.000.05 over1.000.05 over
Chromium16.00 - 18.000.2017.00 - 19.00.20
Nickel10.00 - 14.000.1511.00 - 13.000.15
Molybdenum2.00 - 3.000.10--
Columbium + Tantalum


Grade and ClassDiameterTensile Strength Min KSIYield Strength 0.2% Offset KSIElongation in 4D, Min, %Reduction of Area Min, %Hardness Max BrinellHardness Max Rockwell
B5up to 4" incl100801650--
B6up to 4" incl110851550--
B6Xup to 4" incl90701650-C26
B7to 2-1/2"1251051650-C35
over 2-1/2 to 4"115951650-C35
over 4" to 7"100751850-C35
B7Mup to 4" incl100801850235B99
over 4" to 7"100751850235B99
B16to 2-1/2"1251051850321C35
over 2-1/2" to 4"110951745321C35
over 4" to 7"100851645321C35
Classes 1 and 1D: B8, B8M, B8P, B8LN, B8MLALL75303050223B96
Class 1: B8C, B8TALL75303050223B96
Class 1A: B8A, B8CA, B8MA, B8PA, B8TA, B8LNA, B8MLNA, B8NA, B8MNA, B8MLCuNAALL75303050192B90
Classes 1B & 1D: B8N, B8MN, B8MLCuNALL80353040223B96
Class 1C and 1D: B8RALL100553555271C28
Class 1C: B8RAALL100553555271C28
Classes 1C and 1D: B8SALL95503555271C28
Classes 1C: B8SAALL95503555271C28
Class 2: B8, B8C, B8P, B8T, B8Nto 3/4"1251001235321C35
over 3/4" to 1"115801535321C35
over 1" to 1-1/4"105652045321C35
over 1-1/4 to 1-1/2" incl100502845321C35
Class 2 B8M, B8MN, B8MLCuNto 3/4"110961545321C35
over 3/4" to 1"100802045321C35
over 1" to 1-1/4"95652545321C35
over 1-1/4 to 1-1/2" incl90503045321C35
Class 2B: B8, B8M2to 2" incl95752540321C35
over 2" to 2-1/2" incl90653040321C35
over 2-1/2 " to 3" incl80553040321C35
Class 2C: B8M3to 2" incl85653060321C35

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