What does ASME B18.3.1M socket head cap screws (DIN 912 / ISO 4762) cover?

ASME B18.3.1M is the metric dimensional standard for socket head cap screws (DIN 912 / ISO 4762). It defines head dimensions, body diameter, thread length, total length, drive recess, and tolerances so any compliant socket head cap screws (DIN 912 / ISO 4762) interchanges with standard nuts, washers and wrenches across manufacturers.

What size range is available for socket head cap screws (DIN 912 / ISO 4762) under ASME B18.3.1M?

socket head cap screws (DIN 912 / ISO 4762) under ASME B18.3.1M covers M1.6 through M64 nominal diameter, internal hex drive. TorqBolt manufactures the full range in ASTM A193 Grades B7, B7M, B8, B8M and the full ASTM A320 cryogenic counterpart on customer specification.

What is the metric/inch counterpart of ASME B18.3.1M socket head cap screws (DIN 912 / ISO 4762)?

The companion specification for socket head cap screws (DIN 912 / ISO 4762) is ASME B18.3 inch socket head cap screws. Both standards share equivalent functional dimensions but use the corresponding measurement system (inch vs metric ISO M-series).

ASME B18.3.1M Metric Socket Cap Screws | DIN 912

ASME B18.3.1M Metric Socket Head Cap Screws

Metric cylindrical head socket screws providing high strength and compact installation for precision machinery and global manufacturing.

ASME B18.3.1M Metric Socket Head Cap Screws are the metric standard for high-strength, low-profile fastening, equivalent to the internationally recognized DIN 912 and ISO 4762 standards. Featuring a cylindrical head with an internal hex socket, these screws allow for assembly in confined spaces where external wrench access is impossible. They are manufactured to precise tolerances and are typically made from high-tensile steel (Property Class 12.9), making them suitable for demanding applications in mold making, robotics, automotive engines, and aerospace structures. The metric sizing facilitates their use in equipment designed for global markets, ensuring seamless integration with other metric components. ASME B18.3.1M governs the critical dimensions of the socket, head diameter, and thread pitch, ensuring that these fasteners deliver consistent performance and reliability in high-precision assemblies.

Nom. Sizeand Thread Pitch	Body Diameter, D	Head Diameter A	Head Height H	Chamferor Radius S	Hexagon Socket Size^a J	Spline Socket Size^a M	Key Engagement T	Transition Dia. B ^a
M1.6 × 0.35	1.6	1.46	3	2.87	1.6	1.52	0.16	1.5	1.829	0.8	2
M2 × 0.4	2	1.86	3.8	3.65	2	1.91	0.2	1.5	1.829	1	2.6
M2.5 × 0.45	2.5	2.36	4.5	4.33	2.5	2.4	0.25	2	2.438	1.25	3.1
M3 × 0.5	3	2.86	5.5	5.32	3	2.89	0.3	2.5	2.819	1.5	3.6
M4 × 0.7	4	3.82	7	6.8	4	3.88	0.4	3	3.378	2	4.7
M5 × 0.8	5	4.82	8.5	8.27	5	4.86	0.5	4	4.648	2.5	5.7
M6 × 1	6	5.82	10	9.74	6	5.85	0.6	5	5.486	3	6.8
M8 × 1.25	8	7.78	13	12.7	8	7.83	0.8	6	7.391	4	9.2
M10 × 1.5	10	9.78	16	15.67	10	9.81	1	8	...	5	11.2
M12 × 1.75	12	11.73	18	17.63	12	11.79	1.2	10	...	6	14.2
M14 × 2^b	14	13.73	21	20.6	14	13.77	1.4	12	...	7	16.2
M16 × 2	16	15.73	24	23.58	16	15.76	1.6	14	...	8	18.2
M20 × 2.5	20	19.67	30	29.53	20	19.73	2	17	...	10	22.4
M24 × 3	24	23.67	36	35.48	24	23.7	2.4	19	...	12	26.4
M30 × 3.5	30	29.67	45	44.42	30	29.67	3	22	...	15	33.4
M36 × 4	36	35.61	54	53.37	36	35.64	3.6	27	...	18	39.4
M42 × 4.5	42	41.61	63	62.31	42	41.61	4.2	32	...	21	45.6
M48 × 5	48	47.61	72	71.27	48	47.58	4.8	36	...	24	52.6
a See also Table 25. b The M14 ×2 size is not recommended for use in new designs. All dimensions are in millimeters LG is grip length and LB is body length. For length of complete thread. For additional manufacturing and acceptance specifications, see ASME B18.3.1M-1986.

Nom. Sizeand Thread Pitch

Body Diameter, D

Head Diameter A

Head Height H

Chamferor Radius S

Hexagon Socket Size^a J

Spline Socket Size^a M

Key Engagement T

Transition Dia. B ^a

Max

Min.

Max

Min.

Max

Min.

Max

Nom.

Min.

Max

M1.6 × 0.35

1.6

1.46

2.87

1.6

1.52

0.16

1.5

1.829

0.8

M2 × 0.4

1.86

3.8

3.65

1.91

0.2

1.5

1.829

2.6

M2.5 × 0.45

2.5

2.36

4.5

4.33

2.5

2.4

0.25

2.438

1.25

3.1

M3 × 0.5

2.86

5.5

5.32

2.89

0.3

2.5

2.819

1.5

3.6

M4 × 0.7

3.82

6.8

3.88

0.4

3.378

4.7

M5 × 0.8

4.82

8.5

8.27

4.86

0.5

4.648

2.5

5.7

M6 × 1

5.82

9.74

5.85

0.6

5.486

6.8

M8 × 1.25

7.78

12.7

7.83

0.8

7.391

9.2

M10 × 1.5

9.78

15.67

9.81

...

11.2

M12 × 1.75

11.73

17.63

11.79

1.2

...

14.2

M14 × 2^b

13.73

20.6

13.77

1.4

...

16.2

M16 × 2

15.73

23.58

15.76

1.6

...

18.2

M20 × 2.5

19.67

29.53

19.73

...

22.4

M24 × 3

23.67

35.48

23.7

2.4

...

26.4

M30 × 3.5

29.67

44.42

29.67

...

33.4

M36 × 4

35.61

53.37

35.64

3.6

...

39.4

M42 × 4.5

41.61

62.31

41.61

4.2

...

45.6

M48 × 5

47.61

71.27

47.58

4.8

...

52.6

a See also Table 25.
b The M14 ×2 size is not recommended for use in new designs.
All dimensions are in millimeters
LG is grip length and LB is body length. For length of complete thread.
For additional manufacturing and acceptance specifications, see ASME B18.3.1M-1986.

Frequently Asked Questions

What does ASME B18.3.1M socket head cap screws (DIN 912 / ISO 4762) cover?: ASME B18.3.1M is the metric dimensional standard for socket head cap screws (DIN 912 / ISO 4762). It defines head dimensions, body diameter, thread length, total length, drive recess, and tolerances so any compliant socket head cap screws (DIN 912 / ISO 4762) interchanges with standard nuts, washers and wrenches across manufacturers.
What size range is available for socket head cap screws (DIN 912 / ISO 4762) under ASME B18.3.1M?: socket head cap screws (DIN 912 / ISO 4762) under ASME B18.3.1M covers M1.6 through M64 nominal diameter, internal hex drive. TorqBolt manufactures the full range in ASTM A193 Grades B7, B7M, B8, B8M and the full ASTM A320 cryogenic counterpart on customer specification.
What is the metric/inch counterpart of ASME B18.3.1M socket head cap screws (DIN 912 / ISO 4762)?: The companion specification for socket head cap screws (DIN 912 / ISO 4762) is ASME B18.3 inch socket head cap screws. Both standards share equivalent functional dimensions but use the corresponding measurement system (inch vs metric ISO M-series).

Specifications

Surface Treatments

Xylan 1070 / 1014 / 1400 / 1424

Xylar 2 / 101

Geomet 321 / 500 / 720

SermaGard 1105 / 1280

Dacromet 320 / 500

TakeCoat 1000 Ceramic

Delta Tone/Seal

Magnigard

MolyKote

Sherardized

Zinc-Cobalt (ASTM B840)

Zinc-Nickel (ASTM B841)

Certifications

ISO 9001 - 2015 Certified
PED 2014/68/EC
NACE MR0175/ISO 15156-2
NORSOK M-650
DFAR
MERKBLATT AD 2000 W2/W7/W10

ASME B18.3.1M Metric Socket Head Cap Screws

Frequently Asked Questions

Specifications

Surface Treatments

Certifications

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