Datasheet for Steel Fasteners – Material Selection & Properties

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Material Selection for Steel Fasteners

The below table shows the application of various grades of steel fasteners for different range of temperatures.

Material: Bolt/ Nut Temperature Range
A320B8/Gr 8 (-100°C) – (-200°C)
A320L7/Gr 4 (-46°C) – (-100°C)
A320L7/Gr 4 0°C – (-45°C)
A307 0°C – 300°C
A193 B7 /Gr 2H 300°C – 400°C
A193 B16 /Gr 4 400°C – 550°C
A193 B8 /Gr 8 550°C – 650°C
A193 B8M /Gr 8M 550°C – 650°C

High Temperature High Tension Alloy Bolt Material

ASTM A193 B7 (Cr-Mo) Chemical & Mechanical Properties

This material is considered as the most suitable for bolts to be used at temperature below 450 °C, with a minimum effect on its structural strength during application at a high temperature. The material has the following chemical properties and physical characteristics.

ASTM A193 B7 (Cr-Mo)
Chemical Properties Range (%)
Carbon (C) 0.37 – 0.49
Manganese (Mn) 0.65 – 1.10
Phosphorus (P) 0.035 max
Sulfur (S) 0.04 max
Silicon (Si) 0.15 – 0.35
Chromium (Cr) 0.75 – 1.20
Molybdenum (Mo) 0.15 – 0.25
ASTM A193 B7 (Cr-Mo)
Mechanical Properties 2-1/2″ and under over 2-1/2″ to 4.0″ over 4.0″ to 7.0″
Min Tempering Temperature (F) 1100 (593C) 1100 (593C) 1100 (593C)
Min Tensile Strength (ksi) 125 (860MPa) 115 (795MPa) 100 (690MPa)
Min Yield Strength (ksi) 105 (105MPa) 95 (655MPa) 75 (515MPa)
Elongation in 4D (min %) 16 16 18
Reduction of Area (min %) 50 50 50
Max Hardness 321HB (35HRC) 321HB (35HRC) 277HB (29HRC)

ASTM A1193 B7M (Cr- Mo ) Chemical & Mechanical Properties

ASTM A193 B7M (Cr- Mo )
Chemical Properties Range (%)
Carbon (C) 0.37 – 0.49
Manganese (Mn) 0.65 – 1.10
Phosphorus (P) 0.035 max
Sulfur (S) 0.04 max
Silicon (Si) 0.15 – 0.35
Chromium (Cr) 0.75 – 1.20
Molybdenum (Mo) 0.15 – 0.25
ASTM A193 B7M (Cr- Mo )
Mechanical Properties 4.0″ and under over 4.0″ to 7.0″
Min Tempering Temperature (F) 1150 (620C) 1150 (620C)
(final heat treatment shall be
done after all machining and
forming operations, including
thread rolling and any type
of cutting)
Min Tensile Strength (ksi) 100 (690MPa) 100 (690MPa)
Min Yield Strength (ksi) 80 (550MPa) 75 (515MPa)
Elongation in 4D (min %) 18 18
Reduction of Area (min %) 50 50
Max Hardness 235HB (99HRB) 277HB (29HRC)

 

ASTM A193 B16 (Cr-Mo-V) Chemical & Mechanical Properties

This material is considered as the most suitable for bolts to be used at temperature below 450°C, even at a high temperature range, the material has superior physical characteristics compared to ASTM A193 B7. The chemical properties and physical characteristics are as follows;

ASTM A193 B16 (Cr-Mo-V)
Chemical Properties Range (%)
Carbon (C) 0.36 – 0.47
Manganese (Mn) 0.45 – 0.70
Phosphorus (P) 0.035 Max
Sulfur (S) 0.04 Max
Silicon (Si) 0.15 – 0.35
Chromium (Cr) 0.80 – 1.15
Molybdenum (Mo) 0.50 – 0.65
Aluminum (Al) 0.015 Max
Vanadium (V) 0.25 – 0.35
ASTM A193 B16 (Cr-Mo-V)
Mechanical Properties 2-1/2″ and under over 2-1/2″ to 4.0″ over 4.0″ to 7.0″
Min Tempering Temperature (F) 1200 (650C) 1200 (650C) 1200 (650C)
Min Tensile Strength (ksi) 125 (860MPa) 110 (760MPa) 100 (690MPa)
Min Yield Strength (ksi) 105 (105MPa) 95 (655MPa) 85 (586MPa)
Elongation in 4D (min %) 18 17 16
Reduction of Area (min %) 50 45 45
Max Hardness 321HB (35HRC) 302HB (33HRC) 277HB (29HRC)

ASTM A193 B8 Class1, 1A and 2 (AISI 304) Chemical & Mechanical Properties

ASTM A193 B8 Class1, 1A and 2 (AISI 304)
Chemical Properties Range (%)
Carbon (C) 0.08 Max
Manganese (Mn) 2.00 Max
Phosphorus (P) 0.045 Max
Sulfur (S) 0.030 Max
Silicon (Si) 1.00 Max
Chromium (Cr) 18.00 – 20.00
Nickel (Ni) 8.00 -11.00
Molybdenum (Mo)  –

 

ASTM A193 B8M Class1, 1A and 2 (AISI 316) Chemical & Mechanical Properties

ASTM A193 B8M Class1, 1A and 2 (AISI 316)
Chemical Properties Range (%)
Carbon (C) 0.08 Max
Manganese (Mn) 2.00 Max
Phosphorus (P) 0.045 Max
Sulfur (S) 0.030 Max
Silicon (Si) 1.00 Max
Chromium (Cr) 16.00 – 18.00
Nickel (Ni) 10.00 -14.00
Molybdenum (Mo) 2.00 – 3.00

 

Mechanical Properties Class 1: B8, B8M Class 1A: B8A, B8MA
All diameters All diameters
Heat Treatment Carbide Solution Treated Carbide Solution Treated
in the finished condition
Min Tensile Strength (ksi) 75 (515MPa) 75 (515MPa)
Min Yield Strength (ksi) 30 (205MPa) 30 (205MPa)
Elongation in 4D (min %) 30 30
Reduction of Area (min %) 50 50
Max Hardness 223HB (96HRB) 192HB (90HRC)
        3/4″ and smaller 241HB (100HRB)

 

  B8 Class 2
Mechanical Properties 3/4″ and under over 3/4″ to 1.0″ included over 3/4″ to 1.0″ included over 1-1/4″ to 1-1/2″ included
Heat Treatment Carbide Solution Treated Carbide Solution Treated Carbide Solution Treated Carbide Solution Treated
and Strain Hardened and Strain Hardened and Strain Hardened and Strain Hardened
Min Tensile Strength (ksi) 125 (860MPa) 115 (795MPa) 105 (725MPa) 100 (690MPa)
Min Yield Strength (ksi) 100 (690MPa) 80 (550MPa) 65 (450MPa) 50 (345MPa)
Elongation in 4D (min %) 12 15 20 28
Reduction of Area (min %) 35 35 35 45
Max Hardness 321HB (35HRC) 321HB (35HRC) 321HB (35HRC) 321HB (35HRC)
  B8M Class 2
Mechanical Properties 3/4″ and under over 3/4″ to 1.0″ included over 3/4″ to 1.0″ included over 1-1/4″ to 1-1/2″ included
Heat Treatment Carbide Solution Treated Carbide Solution Treated Carbide Solution Treated Carbide Solution Treated
and Strain Hardened and Strain Hardened and Strain Hardened and Strain Hardened
Min Tensile Strength (ksi) 110 (760MPa) 100 (690MPa) 95 (655MPa) 90 (620MPa)
Min Yield Strength (ksi) 95 (655MPa) 80 (550MPa) 65 (450MPa) 50 (345MPa)
Elongation in 4D (min %) 15 20 25 30
Reduction of Area (min %) 45 45 45 45
Max Hardness 321HB (35HRC) 321HB (35HRC) 321HB (35HRC) 321HB (35HRC)

 

Low-Temperature Alloy Steel Bolt Material

ASTM A320-L7, L7M (Cr-Mo) Chemical & Mechanical Properties

This material is considered as the most suitable for bolts to be used at temperature 0-(-100 °C). The chemical properties and physical characteristics are as follows:

Chemical Properties Range (%)
Carbon (C) 0.38 – 0.48
Manganese (Mn) 0.75 – 1.00
Phosphorus (P) 0.035 max
Sulfur (S) 0.04 max
Silicon (Si) 0.15 – 0.35
Chromium (Cr) 0.80 – 1.10
Molybdenum (Mo) 0.15 – 0.25
Mechanical Properties L7 L7M
2-1/2″ and under
Min Tempering Temperature (F) 1100 (593C) 1150 (620C)
Min Tensile Strength (ksi) 125 (860MPa) 100 (690MPa)
Min Yield Strength (ksi) 105 (725MPa) 80 (550MPa)
Elongation in 4D (min %) 16 18
Reduction of Area (min %) 50 50
Max Hardness 277 – 321HB 235HB or 99HRB
for referecence
Minimum Impact Value ft-lb (J) 20 (27)
(Average of three specimen)
Minimum Impact Value ft-lb (J) 15 (20)
(Specimen of a set)

ASTM A320 B8 (18Cr-8Ni) Chemical & Mechanical Properties

This material is considered as the most suitable for bolts and nuts to be used at temperatures (-)100-(-)200 °C. The chemical properties are as follows:

Chemical Properties B8 B8M
Range (%) Range (%)
Carbon (C) 0.08 max 0.08 max
Manganese (Mn) 2.00 max 2.00 max
Phosphorus (P) 0.045 max 0.045 max
Sulfur (S) 0.30 max 0.30 max
Silicon (Si) 1.00 max 1.00 max
Chromium (Cr) 18.00 – 20.00 16.00 – 18.00
Nickel (Ni) 8.00 – 10.50 10.00 – 14.00
Molybdenum (Mo) 2.00 – 3.00

 

 

Nut Material

ASTM A194

This is the material for bolts made from ASTM A-193 B7, considered to be used with suitable heat treatment. The chemical properties and physical properties are as follows:

Chemical Properties 2H/2HM 4 7/7M 8/8A 8M/8MA
Range (%) Range (%) Range (%) Range (%) Range (%)
Carbon (C) 0.40 min 0.04 – 0.05 0.37 – 0.49 0.08 0.08
Manganese (Mn) 1 0.70 – 0.90 0.65 – 1.10 2 2
Phosphorus (P) 0.04 0.035 0.035 0.045 0.045
Sulfur (S) 0.05 0.04 0.04 0.03 0.03
Silicon (Si) 0.4 0.15 – 0.35 0.15 – 0.35 1 1
Chromium (Cr) 0.75 – 1.20 18.0 – 20.0 16.0 – 18.0
Nickel (Ni) 8.0 – 11.0 10.0 – 14.0
Molybdenum (Mo) 0.20 – 0.30 0.15 – 0.25
  Hardness Requirement
Mechanical Properties Brinell Rockwell-C Scale Rockwell-B Scale
2H (To 1-1/2″ incl) 248 – 327 24 – 35
2H (Over 1-1/2″) 212 – 327 35 max 95 min
2HM/7M 159 – 235 84 – 99
4 and 7 248 – 327 24 – 35
8/8M 126 – 300 60 – 105
8A/8MA 126 – 192 60 – 90

ASTM A307

This material is suitable in structural application where nominal strength along with weldability is required.

Chemical Properties Range (%)
Carbon (C) 0.29
Manganese (Mn) 1.2
Phosphorus (P) 0.04
Sulfur (S)
Gr. A 0.15
Gr. B 0.05
Mechanical Properties Gr. A Gr. B
Min Tempering Temperature (F)
Min Tensile Strength (ksi) 60 (415) 60 – 100
Min Yield Strength (ksi)
Elongation in 4D (min %) 18 18
Reduction of Area (min %)
Max Hardness 121 – 241HB 121 – 212HB