ASTM F738M Specification

F738M specification covers the chemical and mechanical requirements for stainless steel metric bolts, screws, and studs with nominal thread diameters M1.6 through M36 and is intended for use in engineering applications requiring general corrosion resistance.Eight groups of stainless steel alloys are covered, including three austenitic (Grades A1, A2, and A4), one ferritic (Grade F1), three martensitic (Grades C1, C3, and C4), and one precipitation hardening (Grade P1).Twenty property classes are covered, including nine austenitic, two ferritic, eight martensitic, and one precipitation hardening. The property classes with the permissible alloys for each are listed.
This specification is based in concept and content on ISO 3506. The chemical and mechanical requirements specified for all property classes, except as given in 1.4.1, are essentially identical with classes of the same designation in ISO 3506. 1.4.1 This specification includes all of the property classes covered in ISO 3506. Additionally, it includes property classes A1-70, A2-70, A4-70, A1-80, A2-80, and A4-80 for products with nominal thread diameters larger than M20; and four non-ISO property classes, C1-110, C4-110, C3-120; and P1-90. Supplementary requirements of an optional nature are provided, applicable only when agreed upon between the manufacturer and the purchaser at the time of the inquiry and order.Suitable nuts for use with bolts, screws, and studs included in this specification are covered by Specification F836M.

Chemical Composition

Alloy Group Alloy UNS Designation Composition, % maximum except as shown
Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Copper Molybdenum Others
Austenitic Alloys
A1 303 S30300 0.15 2.00 0.20 0.15 min 1.00 17.0-19.0 8.0-10.0   0.60 maxA  
A1 303Se S30323 0.15 2.00 0.20 0.060 1.00 17.0-19.0 8.0-10.0 Se 0.15 min
A1 304 530400 0.06 2.00 0.045 0.030 1.00 16.0-20.0 6.0-10.5 1.00
A1 304L S30403 0.03 2.00 0.045 0.030 1.00 18.0-20.0 8.0-12.0 1.00
A1 305 S30500 0.12 2.00 0.045 0.030 1.00 17.0-19.0 10.5-13.0 1.00
A1 384 S38400 0.08 2.00 0.045 0.030 1.00 15.0-17.0 17.0-19.0
A1 XM1 S20300 0.08 5.0 to 6.5 0.040 0.18 to 0.35 1.00 16.0-18.0 5.0-0.5 1.75-2.25 0.50 maxA
A1 18-9LW S30430 0.10 2.00 0.045 0.030 1.00 17.0-19.0 8.0-10.0 3.0-4.0
A1 302HQ S30433 0.03 2.00 0.045 0.030 1.00 17.0-19.0 8.0-10.0 3.0-4.0
A4 316 S31600 0.08 2.00 0.045 0.030 1.00 16.0-18.0 10.0-14.0 2.00-3.00
A4 316L S31603 0.03 2.00 0.045 0.030 1.00 16.0-18.0 10.0-14.0 2.00-3.00
A2 321 S32100 0.08 2.00 0.045 0.030 1.00 17.0-19.0 9.0-12.0 Ti 5 x C min
A2 347 S34700 0.08 2.00 0.045 0.030 1.00 17.0-19.0 9.0-13.0 Cb + Ta 10 x C min
Ferritic Alloys
F1 430 S43000 0.12 1.00 0.040 0.030 1.00 16.0-18.0        
F1 430F S43020 0.12 1.25 0.060 0.15 min 1.00 16.0-18.0     0.60 maxA  
Martensitic Alloys
C1 410 S41000 0.15 1.00 0.040 0.030 1.00 11.5-13.5
C4 416 S41600 0.15 1.25 0.060 0.15 min 1.00 12.0-14.0 0.60 maxA
C4 416Se S41623 0.15 1.25 0.060 0.060 1.00 12.0-14.0 Se 0.15 min
C3 431 S43100 0.20 1.00 0.040 0.030 1.00 15.0-17.0 1.25-2.50    
Precipitation Hardening Alloy
P1 630 517400 0.07 1.00 0.040 0.030 1.00 15.0-17.5 3.0-5.0 3.0-5.0 Cb + Ta 0.15-0.45
Note:

A. At manufacturer’s option, determined only when intentionally added.

Mechanical Properties

Property Class ConditionA Alloy/ Mechanical Property Marking Nominal Thread Diameter Product LengthB Full Size Product Tests Machined Specimen Tests Hardness
Tensile Strength, MPaC Yield Strength, MPaC,D ExtensionE Torsional Strength, N·mF Tensile Strength, MPa Yield Strength, MPa Elongagation, % Vickers Rockwell
min min min min min min min min max min max
A1-50   F 738A M1.6-M5 all 500     Table 6         165   885
A2-50 AF F 7388 M6-M36 all 500 210 0.6D 500 210 30 165 885
A4-50 F 738C
A1-70 F 7380 M1.6-M5 80 700 Table 6 2.20 330 B96 C33
A2-70 CW F 738E M6–M20 8D 700 450 0.4D 650 400 20 220 330 B96 C33
A4-70 F 738F over M20–M36 80 550 300 0.2D 520 270 25 160 310 883 C31
M1.6-M5 80 800 Table 6 240 350 C23 C36
A1-80 F 738G M6-M20 80 800 600 0.3D 780 600 12 240 350 C23 C36
A2-80 SH F 738H over M20–M24 80 700 500 0.2D 680 480 15 220 330 896 C33
A4-80 F 738J over M24-M30 80 650 400 0.2D 620 370 20 200 310 893 C30
over M30-M36 80 600 300 0.2D 570 270 28 180 285 889 C28
F1-45 AF F 738K M1.6-M5 all 450 165 885
M6-M36 all 450 250 0.2D 450 250 25 165 885
F1-60 CW F 738L M1.6-M5 80 600 180 285 889 C28
M6-M36 80 600 410 0.2D 550 360 20 180 285 889 C28
C1-50 F 738M M1.6-M5 all 500 165 885
C4-50 A F 738N M6-M36 all 500 250 0.2D 500 250 20 165 885
C1-70 F 738P M1.6-M5 all 700 220 330 896 C34
C4-70 H F 738R M6-M36 all 700 410 0.2D 700 410 18 220 330 896 C34
C1-110 F 738S M1.6-M5 all 1100 350 440 C36 C45
C4-110 HT F 738T M6-M36 all 1100 820 0.20 1100 820 12 350 440 C36 C45
C3-80 H F 738U M1.6-M5 all 800 240 340 C23 C35
M6-M36 all 800 640 0.20 800 640 15 240 340 C23 C35
C3-120 HT F 738V M1.6-M5 all 1200 380 480 C39 C48
M6-M36 all 1200 950 0.20 1200 950 10 380 480 C39 C48
Pl-90 AH F 738W M1.6-M5 all 900 285 370 C28 C38
      M6–M36 all 900 700 0.2D . . . 900 700 16 285 370 C28 C38
Note:

A. Legend of conditions:
AF — headed and rolled from annealed stock and then reannealed.
CW — headed and rolled from annealed stock, thus acquiring a degree of cold work; products with nominal thread diameters larger than M20 may be hot-worked and solution annealed.
SH — machined from strain-hardened stock or cold worked to develop the specified properties.
A — machined from annealed or solution-annealed stock, thus retaining the properties of the original material.
H — hardened and tempered at 565°C minimum.
HT — hardened and tempered at 275°C minimum.
AH — solution-annealed and age-hardened after forming.
B. For product lengths: “all” means all lengths “8D ” means 8 times nominal diameter maximum.
C. Tensile strength and yield strength values for full-size products of each property class are given in table on yield and tensile strength.
D. Yield strength is the stress at which an offset of 0.2 % gage lingth occurs.
E. Extension measurement is determined in accordance with the test procedure specified in 10.2.3.
F. Torsional strength requirements apply only to austenitic steel fasteners with nominal thread diameters M5 and smaller. Values are given in table on torsional strength.

TABLE 6 Values for Length x A

Nominal Thread Diameter x, mm
M1.6 4
M2 5
M2.5 6
M3 8
M4 10
MS 12
M6 14
MS 20
M10 25
M12 30
M16 40
M20 45
M24 and larger 30
Note:

A. x equals the minimum length of product subject to tension testing.