ASTM F3125M is a standard material specification covering chemical, physical and mechanical requirements for quenched and tempered bolts manufactured from steel and alloy steel in metric dimensions, in two strength grades, two types and two styles. This specification is a consolidation and replacement of 2 ASTM standards, including; A325M and A490M.

Bolts manufactured under this specification are intended for use in structural connections covered in the Specification for Structural Joints Using High-Strength Bolts, as approved by the Research Council on Structural Connections. Bolts in this specification are furnished in sizes from M12 to M36 inclusive.

Dimensions, Threads, Marking, Matching Components

Metric
830 MPa Min Tensile
Heavy Hex Bolts	Type 1	Type 3	Recommended Nut and Washer	Type 1	Type 3
Dimensions, ASMEB	B18.2.6M	B18.2.6M	Plain Nut	A563M 10S	A563M 10S3
Thread Fit, ASMEB	B1.13M MC 6g	B1.13M MC 6g	Suitable AlternativeE	8S, 8S3, 10S3	8S3
Grade MarkingA,D	A325M	A325M	Coated Nut	A563M 10S	A563M 10S3
...	...	...	Flat, Bevel or Thick Washer if used	F436M - 1	F436M - 3

Metric
1040 MPa Min Tensile
Heavy Hex Bolts	Type 1	Type 3	Recommended Nut and Washer	Type 1	Type 3
Dimensions, ASMEB	B18.2.6M	B18.2.6M	Plain Nut	A563M 10S	A563M 10S3
Thread Fit, ASMEB	B1.13M MC 6g	B1.13M MC 6g	Suitable AlternativeE	10S3	...
Grade MarkingA,D	A490M	A490M	Coated Nut	A563M 10S	A563M 10S3
...	...	...	Flat, Bevel or Thick Washer if used	F436M - 1	F436M - 3

A : A325 and A325M bolts lengths up to 4D which are fully threaded but which are not required to be fully threaded by the relevant ASME standard shall be marked with a “T”, see Supplementary Requirement S1. Bolts with any other non-standard dimensions, including thread length, shall be marked with an “S”, see Supplementary Requirement S2.

B : Manufactured to the latest revision at the time of manufacture, UNC for inch series and Metric Coarse (MC) for Metric Series.

C : Previously used markings may be sold and used indefinitely, bolts must be manufactured to current marking requirements upon initial publication of this standard.

D : Other distinguishing markings for type 3 are permitted at the manufacturers option.

E : ASTM A194/A194M 2H heavy hex inch nuts may be used in place of A563 DH nuts on type 1 A325, A490, F1852 and F2280 bolts. 2H heavy hex metric nuts may be used in place of A563M 10S nuts on type 1 A325M and A490M bolts. When coated 2H nuts are used in place of DH or 10S nuts, the same requirements of A563, A563M,and this specification, including Annex A1, shall apply. These include, but are not limited to, overtap amount, coating grade, lubrication requirements, and proof load testing.

F : Metric dimensions and requirements for this style have not been established.

Chemical Composition

Heat Analysis	120 ksi/830 MPa Minimum				150 ksi/1040 MPa Minimum
	Type 1	Type 3			Type 1	Type 3
	Carbon or Alloy Steel with or without Boron	Composition A	Composition B	Based on Corrosion IndexC	Alloy Steel with or without Boron	Based on Corrosion IndexC
Carbon	0.30 - 0.52	0.33 - 0.40	0.38 -0.48	0.30 - 0.52 max	0.30 - 0.48A	0.30 - 0.53
Manganese	0.60 min	0.90 - 1.20	0.70 - 0.90	0.60 min	0.60 min	0.60 min
Phosphorus, max	0.035	0.035	0.035	0.035	0.035	0.035
Sulfur, max	0.040	0.040	0.040	0.040	0.040	0.040
Silicon	0.15 - 0.30	0.15 - 0.30	0.30 - 0.50	B	B	B
Boron	0.003 max	B	B	B	0.003 max	B
Copper	B	0.25 - 0.45	0.20 - 0.40	0.20 - 0.60	B	0.20 - 0.60
Nickel	B	0.25 - 0.45	0.50 - 0.80	0.20D min	B	0.20D min
Chromium	B	0.45 - 0.65	0.50 - 0.75	0.45 min	B	0.45 min
Vanadium	B	B	B	B	B	B
Molybdenum	B	B	0.06 max	0.10D min	B	0.10D min
Titanium	B	B	B	B	B	B

A Carbon requirement is 0.35-0.53 for 1-1⁄2 in. and M36 diameter bolts.

B Not Specified.

C Type 3 bolts shall be weathering steel and shall conform to the chemical compositions specified in Table 2. Optionally, a chemical composition based on a corrosion index may be used. When qualifying based on the corrosion index the steel shall have a corrosion index of 6 or greater, as calculated from the heat analysis, and as described in Guide G101, using the predictive method based on the data of Larabee and Coburn, or the predictive method based on the data of Townsend. See Guide G101 for methods of estimating the atmospheric corrosion resistance of low alloy steels.

D Either Nickel or Molybdenum must be present in the amount specified.

Mechanical Properties [Bar & Machined Specimen]

Grade	Tensile min.	Tensile max.	Yield min.	Elongation in 4D,min. %	Reduction of Area,min. %
Metric 830 MPa, Grade A325M	830 MPa	...	660 MPa	14	35
Metric 1040 MPa, Grade A490M	1040 MPa	1210 MPa	940 MPa	14	40

Hardness Requirements for Bolts

Diameter	Length	120 ksi/830 MPa Tensile				150 ksi/1040 MPa Tensile
		Brinell HB		Rockwell HRC		Brinell HB		Rockwell HRC
		Min	Max	Min	Max	Min	Max	Min	Max
Up to 1 M24 Inclusive	Less than 2D	253	319	25	34	311	352	33	38
	2D and longer	...	319	...	34	...	352	...	38
Over 1 M24	Less than 3D	253	319	25	34	311	352	33	38
	3D and longer	...	319	...	34	...	352	...	38

Reference Standards