ASTM F 568M Carbon and Alloy Steel Externally Threaded Metric Fasteners

ASTM F568M Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners

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Chemical Composition Requirements

Property
Class		 Nominal Product
Diameter, mm		 Material and Treatment Product Analysis Element (% by weight) Tempering
Temp, °C
C Mn B P S
Min Max Min Max Min Max Min
4.6 M5–M100 low or medium carbon steel . . . 0.55 . . . . . . 0.048 0.058 . . .
4.8 M1.6–M16 low or medium carbon steel, partially or fully annealed as required . . . 0.55 . . . . . . 0.048 0.058 . . .
5.8 M5–M24 low or medium carbon steel, cold worked 0.13 0.55 . . . . . . 0.048 0.058 A . . .
8.8 M20–M80 medium carbon steel, product is quenched and tempered B 0.25 0.55 . . . . . . 0.048 0.058 C 425
8.8 M20–M36 low carbon martensite steel, product is quenched and tempered 0.15 0.40 0.74 0.0005 0.048 0.058 425
8.8.3 M20–M36 atmospheric corrosion resistant steel, product is quenched and tempered 425
9.8 M1.6–M16 medium carbon steel, product is quenched and tempered 0.25 0.55 . . . . . . 0.048 0.058 425
9.8 M1.6–M16 low carbon martensite steel, product is quenched and tempered 0.15 0.40 0.74 0.0005 0.048 0.058 425
10.9 M5–M20 medium carbon steel, product is quenched and tempered E, F 0.25 0.55 . . . . . . 0.048 0.058 425
10.9 M5–M100 medium carbon alloy steel, product is quenched and tempered E 0.20 0.55 . . . . . . 0.040 0.045 425
10.9 M5–M36 low carbon martensite steel, product is quenched and tempered E, F 0.15 0.40 0.74 0.0005 0.048 0.058 340
10.9.3 M16–M36 atmospheric corrosion resistant steel, product is quenched and tempered E 425
12.9 M1.6–M100 alloy steel, product is quenched and tempered E, G 0.31 0.65 . . . . . . 0.045 0.045 380

A For studs only, sulfur content may be 0.33 %, max.
B At the manufacturer’s option, medium-carbon-alloy steel may be used for nominal thread diameters over M24.
C For studs only, sulfur content may be 0.13 %, max.
D Products made using this material shall be specially identified as specified in Section 14.
E Steel for Classes 10.9, 10.9.3, and 12.9 products shall be fine grain and have a hardenability that will achieve a structure of approximately 90 % martensite at the center of a transverse section one diameter from the threaded end of the product after oil quenching.
F Carbon steel may be used at the option of the manufacturer for products of nominal thread diameters M12 and smaller. When approved by the purchaser, carbon steel may be used for products of diameters larger than M12 through M20, inclusive.
G Alloy steel shall be used. Steel is considered to be alloy by the American Iron and Steel Institute when the maximum of the range given for the content of alloying elements exceeds one or more of the following limits: manganese, 1.65 %; silicon, 0.60 %; copper, 0.60 %; or in which a definite range or a definite minimum quantity of any of the following elements is specified or required within the limits of the recognized field of constructional alloy steels: aluminum, chromium up to 3.99 %, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium, zirconium, or any other alloying elements added to obtain a desired alloying effect.


Chemical Composition Requirements for Classes 8.8.3 and 10.9.3

Element Composition, %A
A B C D E F
Carbon:
   Heat analysis 0.33–0.40 0.38–0.48 0.15–0.25 0.15–0.25 0.20–0.25 0.20–0.25
   Product analysis 0.31–0.42 0.36–0.50 0.14–0.26 0.14–0.26 0.18–0.27 0.19–0.26
Manganese:
   Heat analysis 0.90–1.20 0.70–0.90 0.80–1.35 0.40–1.20 0.60–1.00 0.90–1.20
   Product analysis 0.86–1.24 0.67–0.93 0.76–1.39 0.36–1.24 0.56–1.04 0.86–1.24
Phosphorus:
   Heat analysis 0.040 max 0.06–0.12 0.035 max 0.040 max 0.040 max 0.040 max
   Product analysis 0.045 max 0.06–0.125 0.040 max 0.045 max 0.045 max 0.045 max
Sulfur:
   Heat analysis 0.050 max 0.050 max 0.040 max 0.050 max 0.040 max 0.040 max
   Product analysis 0.055 max 0.055 max 0.045 max 0.055 max 0.045 max 0.045 max
Silicon:
   Heat analysis 0.15–0.35 0.30–0.50 0.15–0.35 0.25–0.50 0.15–0.35 0.15–0.35
   Product analysis 0.13–0.37 0.25–0.55 0.13–0.37 0.20–0.55 0.13–0.37 0.13–0.37
Copper:
   Heat analysis 0.25–0.45 0.20–0.40 0.20–0.50 0.30–0.50 0.30–0.60 0.20–0.40
   Product analysis 0.22–0.48 0.17–0.43 0.17–0.53 0.27–0.53 0.27–0.63 0.17–0.43
Nickel:
   Heat analysis 0.25–0.45 0.50–0.80 0.25–0.50 0.50–0.80 0.30–0.60 0.20–0.40
   Product analysis 0.22–0.48 0.47–0.83 0.22–0.53 0.47–0.83 0.27–0.63 0.17–0.43
Chromium:
   Heat analysis 0.45–0.65 0.50–0.75 0.30–0.50 0.50–1.00 0.60–0.90 0.45–0.65
   Product analysis 0.42–0.68 0.47–0.83 0.27–0.53 0.45–1.05 0.55–0.95 0.42–0.68
Vanadium:
   Heat analysis . . . . . . 0.020 min . . . . . . . . .
   Product analysis . . . . . . 0.010 min . . . . . . . . .
Molybdenum:
   Heat analysis . . . 0.06 max . . . 0.10 max . . . . . .
   Product analysis . . . 0.07 max . . . 0.11 max . . . . . .
Titanium:
   Heat analysis . . . . . . . . . 0.05 max . . . . . .
   Product analysis . . . . . . . . . . . . . . . . . .
A A, B, C, D, E, and F are types of material used for Property Classes 8.8.3 and 10.9.3 bolts, screws, and studs. Selection of a composition shall be at the option of the product manufacturer except that sizes M20 and larger shall conform to Composition A or B only.

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