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Technical datasheet DIN 931 / ISO 4014 — Hexagon head bolt, part thread

Reference only — for design, verification or contractual purposes refer to the current issue of the original standard. MF Fastener Industries LLC · sales@mfindllc.com · +971 6 767 2469 · mfindllc.com

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Dimensional datasheet

DIN 931 hex bolt

Hexagon head bolt with a plain shank and a threaded portion. Metric coarse thread. The part-threaded counterpart to DIN 933. Use it where the joint needs a plain shank in shear, or where the grip length must be controlled.

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d nominal thread diameters width across flatse width across cornersk head heightl length under headb thread length

Dimensions

millimetres

Nominal dimensions for metric coarse thread. Head dimensions are identical to DIN 933. Thread length b varies with the bolt length, and the three columns below cover the three length bands.

Size	Pitch	s — across flats	Spanner size	e — across corners	k — head height	b (l ≤ 125)	b (125 < l ≤ 200)	b (l > 200)
M6	1.00	10.00	10 mm	11.05	4.00	18	24	31
M8	1.25	13.00	13 mm	14.38	5.30	22	28	35
M10	1.50	16.00 (DIN 17.00)	16 mm / 17 mm	17.77	6.40	26	32	39
M12	1.75	18.00 (DIN 19.00)	18 mm / 19 mm	20.03	7.50	30	36	43
M16	2.00	24.00	24 mm	26.75	10.00	38	44	51
M20	2.50	30.00	30 mm	33.53	12.50	46	52	59
M24	3.00	36.00	36 mm	39.98	15.00	54	60	67
M30	3.50	46.00	46 mm	50.85	18.70	66	72	79
M36	4.00	55.00	55 mm	60.79	22.50	78	84	91

Thread length is not fixed

b is calculated from the bolt length: 2d + 6 up to 125 mm, 2d + 12 from 125 to 200 mm, 2d + 25 above 200 mm.

This matters when the grip length is critical. A longer bolt of the same diameter has a longer thread, which shortens the plain shank. If the shank must span the joint, check the figure before ordering.

M10 and M12 — check before you order

DIN 931 originally specified 17 mm across flats at M10 and 19 mm at M12. ISO 4014 specifies 16 mm and 18 mm. Most current production follows ISO.

That means two different spanner sizes for the same nominal bolt.

If you are replacing bolts in an existing assembly, say which you need on the order.

Property classes

ISO 898-1

Class	Tensile strength Rm min	Yield Rp0.2 min	Hardness HV	Typical use
4.6	400 N/mm²	240 N/mm²	120 – 220	General, non-structural
5.6	500 N/mm²	300 N/mm²	155 – 220	General engineering
8.8	800 N/mm²	640 N/mm²	250 – 320	Structural and machine
10.9	1040 N/mm²	940 N/mm²	320 – 380	High duty
12.9	1220 N/mm²	1100 N/mm²	385 – 435	Highest duty, tool joints

Values for sizes up to M39. Property class is marked on the head. Classes 10.9 and 12.9 are susceptible to hydrogen embrittlement where electroplated — specify the coating at order stage so it can be baked correctly.

At a glance

Standard	DIN 931 · ISO 4014 · BS EN ISO 4014
Head	Hexagon
Thread	Part thread, plain shank under head
Thread form	Metric coarse, ISO 68-1
Tolerance	6g as standard
Full thread version	DIN 933 · ISO 4017
Matching nut	DIN 934 · ISO 4032
Matching washer	DIN 125A · ISO 7089

Supply

Imported and held in stock. Sourced from established mills in Europe, China, India and the Far East and supplied from our warehouse in Umm Al Quwain.

Anchor bolts, studs and plate washers are manufactured at our own plant. This item is not.

Materials and finish

Carbon steel	Plain, zinc plated, hot-dip galvanized
Stainless	A2-70, A4-80
High tensile	8.8, 10.9, 12.9
Certification	Mill certificate against lot and heat number

Testing

Dimensional and thread inspection is carried out in our own plant on calibrated instruments. Tensile, hardness and chemical testing is carried out by independent UAE-accredited laboratories.

Reference only

This datasheet is published for reference. Dimensions and property values are reproduced in good faith from published standards, but for design, verification or contractual purposes always refer to the current issue of the original standard.

If a figure here conflicts with the standard, the standard governs.

Need a quotation?

Send the size, length, property class, coating and quantity. Tell us if the grip length matters so we can check the thread length suits.