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DIN931 Hex Head Bolts

DIN 931 is a metric partial-threaded hex head bolt. Its main feature is that the bolt rod does not have threads throughout, but rather a section of smooth rod is retained near the bolt head, and then threads are machined from the designated position. Compared with the full-threaded DIN 933 hex bolt, the smooth rod part of DIN 931 can be used for positioning between components and can avoid having the threads directly located in the main shear or mating area. Therefore, it is often used in mechanical equipment, steel structures, metal frames, and other assembly scenarios that require semi-threaded bolt connections. DIN 931 mainly stipulates dimensions and structure, and specific materials and mechanical properties can be referred to according to the requirements by consulting corresponding standards such as ISO 898-1 and ISO 3506-1.

Specification:

The partial-threaded structure of DIN 931 has clear requirements for the length of the shank, the length of the thread and the connection dimensions between the thread and the shank. During the production process, we control these key dimensions according to different specifications, and combine corresponding threading, machining and heat treatment processes to ensure that the size, thread and mechanical properties of the bolts meet the specified standards. The surface treatment can also be selected according to the material and usage environment.

Item	Specification
Standard	DIN931
Head Type	External Hexagon
Product Type	Partially Threaded Hexagon Head Bolt
Thread Type	Metric Coarse Thread(ISO965)
Thread Configuration	Partially Threaded
Thread Diameter	M1.6 – M160
Thread Toelrance	6g
Head Type	Hexagon head, suitable for tightening with a wrench or socket
Material	Carbon Steel,Alloy Steel,Stainless Steel,Aluminum
Steel Mechanical Standard	ISO898-1
Steel Property Class	4.8,8.8,10.9,12.9
Stainless Steel Mechanical Standard	ISO3506-1
Stainless Steel Class	A2-70,A2-80,A4-70,A4-80
Surface treatment	Dimensional,Thread,Mechanical Proeprty,Coating

Dimension Chart of DIN931 Hex Bolts:

DIN 931 dimensions include the nominal diameter, overall length, thread length, plain shank length, head width across flats, and head height. When selecting the bolt, the thread length and unthreaded section should be checked against the thickness of the components being joined.

Our dimension chart provides the key dimensions for each available size, helping customers select a bolt with sufficient grip length and nut engagement while maintaining the required clearance around the hex head. Selection Tip: For DIN 931, overall length alone does not determine whether the bolt is suitable. The position and length of the threaded section should also be considered when the joint requires a defined plain shank.

Mon	M1.6	M2	M2.5	M3	M3.5	M4	M5	M6	M8	M10	M12	M14	M16	M18	M20	M22	M24	M27	M30	M33	M36	M39
P	0.35	0.4	0.45	0.5	0.6	0.7	0.8	1	1.25	1.5	1.75	2	2	2.5	2.5	2.5	3	3	3.5	3.5	4	4
da max	2	2.6	3.1	3.6	4.1	4.7	5.7	6.8	9.2	11.2	13.7	15.7	17.7	20.2	22.4	24.4	26.4	30.4	33.4	36.4	39.4	42.4
ds max	1.6	2	2.5	3	3.5	4	5	6	8	10	12	14	16	18	20	22	24	27	30	33	36	39
ds min	1.46	1.86	2.36	2.86	3.32	3.82	4.82	5.82	7.78	9.78	11.73	13.73	15.73	17.73	19.67	21.67	23.67	26.48	29.48	32.38	35.38	38.38
e min	3.41	4.32	5.45	6.01	6.58	7.66	8.79	11.05	14.38	18.9	21.1	24.49	26.75	30.14	33.53	35.72	39.98	45.2	50.85	55.37	60.79	66.44
k max	1.22	1.52	1.82	2.12	2.52	2.92	3.65	4.15	5.45	6.58	7.68	8.98	10.18	11.72	12.72	14.22	15.22	17.35	19.12	21.42	22.92	25.42
k min	0.98	1.28	1.58	1.88	2.28	2.68	3.35	3.85	5.15	6.22	7.32	8.62	9.82	11.28	12.28	13.78	14.78	16.65	18.28	20.58	22.08	24.58
r min	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.25	0.4	0.4	0.6	0.6	0.6	0.6	0.8	0.8	0.8	1	1	1	1	1
s max	3.2	4	5	5.5	6	7	8	10	13	17	19	22	24	27	30	32	36	41	46	50	55	60
s min	3.02	3.82	4.82	5.32	5.82	6.78	7.78	9.78	12.73	16.73	18.67	21.67	23.67	26.67	29.67	31.61	35.38	40	45	49	53.8	58.8

Mechanical Proeprty of DIN931 Hex Bolts:

ISO 898-1

The DIN 931 hex bolts made of carbon steel and alloy steel can be provided with different performance grades according to ISO 898-1. The commonly used grades include 4.8, 8.8, 10.9 and 12.9. The 8.8 grade is suitable for regular strength connections in mechanical equipment, steel structures and general industrial assemblies. The 10.9 grade has higher tensile strength and yield strength and is suitable for connections subjected to higher mechanical loads.

ISO3506-1

The stainless steel DIN 931 hex bolts can be provided according to ISO 3506-1 with common performance grades such as A2-70, A2-80, A4-70 and A4-80. The A2 series is usually produced using 304 or 304L stainless steel. In humid or corrosive environments, the A4 series DIN 931 hex bolts will be used, and the A4 series will be produced using 316 or 316L materials. The minimum tensile strength of A2-80 and A4-80 is 800 MPa, which is suitable for connections that require both high mechanical strength.

Application of DIN931 Hex Bolt:

The DIN 931 hex bolts are widely used in mechanical equipment, industrial machinery, steel structures, metal frames, and various equipment assemblies. Some of their threaded structures are suitable for connections requiring specific thread lengths, and the appropriate bolt length can be selected based on the thickness of the connecting components and assembly requirements. Carbon steel and alloy steel DIN 931 bolts can be used for regular and high-strength connections in mechanical equipment and structural components, while stainless steel DIN 931 bolts are suitable for assembly in humid, outdoor, and corrosive environments. Different mechanical performance grades and surface treatments can also be chosen according to specific working conditions.

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