DIN 931 (ISO4014) hexagonal head bolts with shank, also called semi-threaded hexagonal bolts or half threaded hexagonal bolts, according to the thread length. DIN 931 hexagon bolts are often used in conjunction with hex nuts. the tow parts are connected into a whole by threaded connection, which is a detachable connection. the self-locking performance of the fine thread hexagonal bolt is better, and it is mostly used for parts subject to greater impact, vibration or alternating load, can also be used for fine adjustment mechanism.
DIN 931 Product Details
The DIN 931 hexagonal bolt is semi-threaded hexagonal bolts with thread diameters of M6-M56, product grades A and B. Class A: d≤24mm and l≤10d or l≤150mm (according to the smaller value). Grade B: d>24 mm or l>10d or 1>150 mm. (Press the smaller value). Different product grades have different values for the corresponding opposite side s, diagonal e, thickness k and length tolerance.
The general thread diameter specification is M6-M56, and the general carbon steel performance grade is mainly 8.8 and 10.9. When d≤39mm, refer to ISO898-1.
Surface treatment and thread tolerance: DIN933 hexagon bolts are generally metric (coarse) and fine pitch, with mm millimeters as the unit of measurement.
DIN931 coarse thread tolerance is: 6g, the coating is mainly boiled black, electroplating (blue and white zinc, yellow color zinc), non-electrolytic zinc powder coating (GEO). The tolerance matching before coating is mainly 6g/6H, and the tolerance zone matching after galvanizing can be changed to 6h/6G. However, after coating, it is affected by the thickness of the surface coating. When the thread is inspected by the corresponding tolerance, it is also There may be situations where it cannot be matched, and only nuts with matching specifications can be tested.
Regarding the mechanical performance test:
general appearance test and pass-and-limit test are common and necessary tests, and the following test items are carried out according to the actual situation
→ Tensile test: When the specific specifications and length meet the conditions, high-strength carbon steel (8.8, 10.9, 12.9) Carbon steel: 8.8 grade not less than 800MPa/830MPa (greater than m16); 10.9 grade not less than 1000MPa; 12.9 grade not less than 1200MPa.
→Impact test: Carbon steel products can be subjected to impact test when the specifications meet certain conditions.
→Hardness test: Carbon steel products can be tested for surface hardness and core hardness.
→Torsion test: For small-size products, the tensile test cannot be performed, but the torsion test can be performed.
→Wedge load: high-strength carbon steel products can be tested for selective wedge load.