ASTM A193 Bolts

ASTM A193 specification covers alloy steel and stainless steel bolting material for pressure vessels, valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. Ferritic steels are heat treated as best suits the high temperature characteristics of each grade. Immediately after rolling or forging, the bolting material shall be allowed to cool to a temperature below the cooling transformation range.

ASTM A193 Bolts, Screws, Studs, Stud Bolts, Threaded Rod Manufacturers and Suppliers

A193 Bolting Materials and bolting components supplied to this specification shall conform to the requirements of Specification A962/A962M. These requirements include test methods, finish, thread dimensions, macroetch (alloy steels only), marking, certification, optional supplementary requirements, and others. Failure to comply with the requirements of Specification A962/A962M constitutes nonconformance with this specification. In case of conflict between this specification and Specification A962/A962M, this specification shall prevail.ASTM A193 Bolts,screws,studs,andstud bolts shall be pointed and shall have a workmanlike finish. Points shall be flat and chamfered or rounded at option of the manufacturer. Length of point on studs and stud bolts shall be not less than one nor more than two complete threads as measured from the extreme end parallel to the axis. Length of studs and stud bolts shall be measured from first thread to first thread.

Most Common Grades of ASTM A193 Bolts

ASTM A193 Grade B5 Bolts – Quenched and tempered Stainless Steel 501

ASTM A193 Grade B6 Bolts – Martensitic Stainless Steel 410

ASTM A193 Grade B7 Bolts – Alloy Steel AISI 4140/4135/4142 Quenched and Tempered

ASTM A193 Grade B7M Bolts – ASTM A193 Grade B7M Bolts Alloy Steel AISI 4140/4135/4142 Quenched, Tempered & 100% Hardness Tested

ASTM A193 Grade B16 Bolts – Chromium- Molybdenum-Vanadium Alloy Steel Quenched and Tempered

ASTM A193 Grade B8 Bolts – Class1 Stainless Steel 304 Carbide solution Treated

ASTM A193 Grade B8M Bolts – Class1 Stainless Steel 316 Carbide solution Treated

ASTM A193 Grade B8M Bolts – Class 2 Stainless Steel 316 Carbide solution Treated and Strain Hardened

ASTM A193 Grade B8MLCuN Bolts – 254 Smo Stainless Steel Solution Annealed

Chemical Composition

ASTM A193 Chemical Composition

TypeFerritic Steels
GradeB5B6 and B6X
UNS Designation5% Chromium12% Chromium
S 41000 (410)
RangeProduct Variation, Over or UnderRangeProduct Variation, Over or Under
Carbon0.1 min0.01 under0.15 max0.01 over
Manganese, MAX1.000.03 over1.000.03 over
Phosphorus, MAX0.0400.005 over0.0400.005 over
Sulfur, MAX0.0300.005 over0.0300.005 over
Silicon1.00 max0.05 over1.00 max0.05 over
Chromium4.0-6.00.1011.5-13.50.15
Molybdenum0.40-0.650.05

FERRITIC STEELS

GradeB7, B7MB16
DescriptionChromium-MolybdenumChromium-Molybdenum-Vanadium
RangeProduct Variation, Over or UnderRangeProduct Variation, Over or Under
Carbon0.37-0.490.010.36-0.470.02
Manganese0.65-1.100.040.45-0.700.03
Phosphorus, MAX0.0350.005 over0.0350.005 over
Sulfur, MAX0.0400.005 over0.0400.005 over
Silicon0.15-0.350.020.15-0.350.02
Chromium0.75-1.200.050.80-1.150.05
Molybdenum0.15-0.250.020.50-0.650.03
Vanadium0.25-0.350.03
Aluminum, MAX %0.015

AUSTENITIC STEEL, CLASSES 1, 1A, 1D, AND 2

GradeB8, B8AB8C, B8CAB8M, B8MA, B8M2, B8M3B8P, B8PA

UNS DesignationS 30400 (304)S 34700 (347)S 31600 (316)S 30500
RangeProduct Variation, Over or UnderRangeProduct Variation, Over or UnderRangeProduct Variation, Over or UnderRangeProduct Variation, Over or Under
Carbon, MAX0.080.01 over0.080.01 over0.080.01 over0.120.01 over
Manganese, MAX2.000.04 over2.000.04 over2.000.04 over2.000.04 over
Phosphorus, MAX0.0450.010 over0.0450.010 over0.0450.010 over0.0450.010 over
Sulfur, MAX0.0300.005 over0.0300.005 over0.0300.005 over0.0300.005 over
Silicon MAX1.000.05 over1.000.05 over1.000.05 over1.000.05 over
Chromium18.0-20.00.2017.0-19.00.2016.0-18.00.2017.0-19.00.20
Nickel8.0-11.00.159.0-12.00.1510.0-14.00.1511.0-13.00.15
Molybdenum2.00-3.000.10
Columbium + Tantalum10 x carbon content, min; 1.10 max0.05 under

AUSTENITIC STEEL, CLASSES 1A, 1B, 1D, AND 2

GradeB8N, B8NAB8MN, B8MNAB8MLCuN, B8MLCuNA

UNS DesignationS 30451 (304N)S 31651 (316N)S 31254
 RangeProduct Variation, Over or UnderRangeProduct Variation, Over or UnderRange
Carbon, MAX0.080.01 over0.080.01 over0.0200.01 over
Manganese, MAX2.000.04 over2.000.04 over1.000.04 over
Phosphorus, MAX0.0450.010 over0.0450.010 over0.0300.010 over
Sulfur, MAX0.0300.005 over0.0300.005 over0.0100.005 over
Silicon, MAX1.000.05 over1.000.05 over0.800.05 over
Chromium18.0-20.00.2016.0-18.00.2019.5-20.50.20
Nickel8.0-11.00.1510.0-13.00.1517.5-18.50.15
Molybdenum2.00-3.000.106.0-6.50.10
Niltrogen0.10-0.160.010.10-0.160.010.18-0.22
Copper0.50-1.00

AUSTENITIC STEEL, CLASSES 1, 1A, AND 2

GradeB8T, B8TA
UNS DesignationS 32100 (321)
RangeProduct Variation, Over or Under
Carbon, MAX0.080.01 over
Manganese, MAX2.000.04 over
Phosphorus, MAX0.0450.010 over
Sulfur, MAX0.0300.005 over
Silicon, MAX1.000.05 over
Nickel9.0-12.00.15
Chromium17.0-19.00.20
Titanium5 x (C + N) min, 0.70 max0.05 under

Austenitic Steel, Classes 1C and 1D

GradeB8R, B8RAB8S, B8SA
UNS DesignationS 20910S 21800
RangeProduct Variation, Over or UnderRangeProduct Variation, Over or Under
Carbon, max0.060.01 over0.100.01 over
Manganese4.0-6.00.057.0-9.00.06
Phosphorus, max0.0450.005 over0.0600.005 over
Sulfur, max0.0300.005 over0.0300.005 over
Silicon1.00 max0.05 over3.5-4.50.15
Chromium20.5-23.50.2516.0-18.00.20
Nickel11.5-13.50.158.0-9.00.10
Molybdenum1.50-3.000.10
Niltrogen0.20-0.400.020.08-0.180.01
Columbium + Tantalum0.10-0.300.05
Vanadium0.10-0.300.02

Austenitic Steel, Classes 1, 1A and 1D

GradeB8LN, B8LNAB8MLN, B8MLNA
UNS DesignationS 30453S 31653
RangeProduct Variation, Over or UnderRangeProduct Variation, Over or Under
Carbon, max0.0300.005 over0.0300.005 over
Manganese2.000.04 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
Chromium18.0-20.00.2016.0-18.00.20
Nickel8.0-11.00.1510.0-13.00.15
Molybdenum2.00-3.000.10
Niltrogen0.10-0.160.010.10-0.160.01

Mechanical Properties

ASTM A193 Mechanical Properties

Ferritic Steels

GradeDiameter, in.Minimum Tempering Temperature, °FTensile Strength, min, ksiYield Strength, min, 0.2% offset, ksiElongation in 4D, min, %Reduction of Area, min, %Hardness, max
B5, 4 to 6% chromiumup to 4, incl1100100801650
B6, 13% chromiumup to 4, incl1100110851550
B6X, 13% chromiumup to 4, incl11009070165026 HRC
B7, Chromium-molybdenum2 1/2 and under11001251051650321 HB or 35HRC
over 2 1/2 to 411OO115951650321 HB or 35HRC
over 4 to 71100100751850321 HB or 35HRC
B7M, Chromium-molybdenum4 and under1150100801850235 HB or 99HRB
over 4 to 71150100751850235 HB or 99HRB
B16, Chromium-molybdenum-vanadium2 1/2 and under12001251051850321 HB or 35HRC
over 2 1/2 to 41200110951745321 HB or 35HRC
over 4 to 81200100851645321 HB or 35HRC

Austenitic Steels

GradeDiameter, in.Heat TreatmentTensile Strength, min, ksiYield Strength, min, 0.2% offset, ksiElongation in 4D, min, %Reduction of Area, min, %Hardness, max
Classes 1 and 1D: B8, B8M, B8P, B8LN, B8MLNall diameterscarbide solution treated75303050223 HB or 96 HRB
Classes 1: B8C, B8Tall diameterscarbide solution treated75303050223 HB or 96 HRB
Classes 1A: B8A, B8CA, B8MA, B8PA, B8TA, B8LNA, B8MLNA, B8NA, B8MNA, B8MLCuNAall diameterscarbide solution treated in the finished condition75303050192 HB or 90 HRB
Classes 1B and 1D: B8N, B8MN, and B8MLCuNall diameterscarbide solution treated80353040223 HB or 96 HRB
Classes 1C and 1D: B8Rall diameterscarbide solution treated100553555271 HB or 28 HRC
Classes 1C: B8RAall diameterscarbide solution treated in the finished condition100553555271 HB or 28 HRC
Classes 1C and 1D: B8Sall diameterscarbide solution treated95503555271 HB or 28 HRC
Classes 1C: B8SAall diameterscarbide solution treated in the finished condition95503555271 HB or 28 HRC
Classes 2: B8, B8C, B8P, B8T, and B8N3/4 and undercarbide solution treated in the finished condition1251001235321 HB or 35 HRC
over 3/4 to 1, incl115801535321 HB or 35 HRC
over 1 to 1 1/4, incl105652035321 HB or 35 HRC
over 1 1/4 to 1 1/2, incl100502845321 HB or 35 HRC
Classes 2: B8M, B8MN, B8MLCuN3/4 and undercarbide solution treated in the finished condition110951545321 HB or 35 HRC
over 3/4 to 1, incl100802045321 HB or 35 HRC
over 1 to 1 1/4, incl95652545321 HB or 35 HRC
over 1 1/4 to 1 1/2, incl90503045321 HB or 35 HRC
Class 2B: B8, B8M22 and undercarbide solution treated in the finished condition95752540321 HB or 35 HRC
over 2 to 2 1/2 incl90653040321 HB or 35 HRC
over 2 1/2 to 3 incl80553040321 HB or 35 HRC
Class 2C: B8M32 and undercarbide solution treated in the finished condition85653060321 HB or 35 HRC
over 285603060321 HB or 35 HRC

Ferritic Steels

ClassDiameter, (mm)Minimum Tempering Temperature, °CTensile Strength, min, MPaYield Strength, min, 0.2% offset, ksiElongation in 4D, min, %Reduction of Area, min, %Hardness, max
B5, 4 to 6% chromiumup to M100, incl5936905501650
B6, 13% chromiumup to M100, incl5937605851550
B6X, 13% chromiumup to M100, incl593620485165026 HRC
B7, Chromium-molybdenumM64 and under5938607201650321 HB or 35HRC
over M64 to M1005937956551650321 HB or 35HRC
over M100 to M1805936905151850321 HB or 35HRC
B7M, Chromium-molybdenumM100 and under6206905501850235 HB or 99HRB
over M100 to M1806206905151850235 HB or 99HRB
B16, Chromium-molybdenum-vanadiumM64 and under6508607251850321 HB or 35HRC
over M64 to M1006507606551745321 HB or 35HRC
over M100 to M1806506905881645321 HB or 35HRC

Austenitic Steels

GradeDiameter, (mm)Heat TreatmentTensile Strength, min, MPaYield Strength, min, 0.2% offset, MPaElongation in 4D, min, %Reduction of Area, min, %Hardness, max
Classes 1 and 1D: B8, B8M, B8P, B8LN, B8MLNall diameterscarbide solution treated5152053050223 HB or 96 HRB
Classes 1: B8C, B8Tall diameterscarbide solution treated5152053050223 HB or 96 HRB
Classes 1A: B8A, B8CA, B8MA, B8PA, B8TA, B8LNA, B8MLNA, B8NA, B8MNA, B8MLCuNAall diameterscarbide solution treated in the finished condition5152053050192 HB or 90 HRB
Classes 1B and 1D: B8N, B8MN, and B8MLCuNall diameterscarbide solution treated5502403040223 HB or 96 HRB
Classes 1C and 1D: B8Rall diameterscarbide solution treated6903603555271 HB or 28 HRC
Classes 1C: B8RAall diameterscarbide solution treated in the finished condition6903603555271 HB or 28 HRC
Classes 1C and 1D: B8Sall diameterscarbide solution treated6553453555271 HB or 28 HRC
Classes 1C: B8SAall diameterscarbide solution treated in the finished condition6553453555271 HB or 28 HRC
Classes 2: B8, B8C, B8P, B8T, and B8N3/4 and undercarbide solution treated in the finished condition8606901235321 HB or 35 HRC
over 3/4 to 1, incl7955501535321 HB or 35 HRC
over 1 to 1 1/4, incl7254502035321 HB or 35 HRC
over 1 1/4 to 1 1/2, incl6903452845321 HB or 35 HRC
Classes 2: B8M, B8MN, B8MLCuN3/4 and undercarbide solution treated in the finished condition7606651545321 HB or 35 HRC
over 3/4 to 1, incl6905502045321 HB or 35 HRC
over 1 to 1 1/4, incl6554502545321 HB or 35 HRC
over 1 1/4 to 1 1/2, incl6203453045321 HB or 35 HRC
Class 2B: B8, B8M22 and undercarbide solution treated in the finished condition6555152540321 HB or 35 HRC
over 2 to 2 1/2 incl6204503040321 HB or 35 HRC
over 2 1/2 to 3 incl5503803040321 HB or 35 HRC
Class 2C: B8M32 and undercarbide solution treated in the finished condition5854503060321 HB or 35 HRC
over 25854153060321 HB or 35 HRC
Download PDF: ASTM A193 at ASTM.org

Related ASTM Specification

ASTM A320 / A320M – 15a : Standard Specification for Alloy-Steel and Stainless Steel Bolting for Low-Temperature Service

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ASTM F2281 : Standard Specification for Stainless Steel and Nickel Alloy Bolts, Hex Cap Screws, and Studs, for Heat Resistance and High Temperature Applications Designation

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