Carbon steel black oxide ASTM A490 Hex cup Bolts High Strength
American-made A325 high strength screw screw A490 high strength
bolt (HSBs). Material: A325 A490 A449 Product categories: American
A325 bolts TYPE 1 A490 bolts according to standard: specification:
1 / 2 1 / 1 / 2. Between ASTM high strength bolts applicable: 1:
American-made A325 TYPE1 carbon content. Carbon boron or medium
carbon alloy steel, suitable for general steel structures,
available for hot dip galvanizing... American A325 TYPE2
1991/11.TYPE3 weathering steel. Weathering resistance equivalent to
A242 / A566 / A709 and other steels. Suitable for use with
weathering steels. Can be hot-dip galvanized. 2: American A490
TYPE1. Bolts are made of alloy steel. Nominal diameter 1/2 "1 1/2",
suitable for general steel structure, not hot-dip galvanized.
American A490 TYPE2 bolts are usually made of low carbon bada loose
iron steel. Nominal diameter 1/2 "1 1/2", not hot-dip galvanized.
American A490 TYPE3 weathering steel, weathering resistance
equivalent to A2422.A588 / A709 and so on. Suitable for use with
weathering steel. Not hot-dip galvanized three: American A449 TYPE1
carbon content. Nominal diameter is 1/4 "3". Suitable for general
steel structure, it can be used for high temperature resistance,
can be hot-dip galvanized. American made of A449 TYPE2 low carbon
hematite loose iron steel. Nominal diameter is 1/4 "1". Non-hot-dip
galvanizing-Table 1: minimum pretension bolts nominal diameters for
ASTM A325 and ASTM A490 bolts) minimum pretensile force TB / tf)
Several concepts about high strength bolts 1. According to the
specification of bolt performance class 8.8 or above, called high
strength bolt. The current national standard only listed to M39,
for large size specifications. In particular, the length of 15
times the length of high-strength bolts, domestic production is
Distinction between high strength bolts and ordinary bolts:
High-strength bolts are larger than ordinary bolts of the same
The material for ordinary bolts is made of Q 235 (A 3).
High strength outer hexagon bolt
High-strength bolt material 3 steel or other high-quality
materials, made after heat treatment, improve the strength.
The difference between the two is the difference in the strength of
From the perspective of raw materials:
The high strength bolt is made of high strength material. The
screw, nut and gasket of high strength bolt are made of high
strength steel. 35CrMoA, etc. Common bolts are made of Q235 steel
(equivalent to A 3 in the past).
In terms of strength:
High strength T-groove bolt
High strength bolts are widely used. Two strength grades of 8.8s
and 10.9s are commonly used, of which 10.9 grade is the majority.
Ordinary bolts have a low strength grade of 4.4 grade or 4.8 grade.
Levels 5.6 and 8.8.
From the point of view of stress characteristics: high strength
bolts apply pretension force and transfer external force by
friction. Ordinary bolts connect by bolt shear resistance and hole
wall pressure to transfer shear force, and the pre-tension force is
very small when the nut is tightened. In addition to the high
strength of the material, the high strength bolt exerts a large
pretension force, which causes the extrusion force between the
connecting members and makes the friction force perpendicular to
the screw direction very large. The bearing capacity of
high-strength bolts is directly affected by pretension, slip
resistance and steel type.
|Item||Black Structural Bolt Heavy Hex Head Bolts|
|Type||Flange Bolt,Carriage bolt, Guardrail bolt,Socket Bolt,T bolt,Square
bolt and Wing bolt|
|Grade||Gr4.8 Gr8.8 Gr2 Gr5 A325 A490|
|Standard:||DIN933,DIN931DIN6923.DIN603 DIN912 DIN444,DIN315,ASME B18.2.3,ASME
|Material||Stainless Steel: SS201 SS304/SS304L SS316/SS316L SS904L|
A2 A4 GR.B8 GRB8M
|Steel Grade: Gr.4.8,5.8,8.8,10.9,12.9; SAE: Gr.2,5,8;|
|Finishing:||Zinc(Yellow,White,Blue,Black,Colour),Hop Dip Galvanized(HDG),Black
Oxide,Geomet,Dacroment,Nickel plated,Zinc-Nickel plated,Telfon|
|Production Technique||Cold forging, Hot forming, Machining, Heat treatment, Staming, etc|
|Stock Products||Stainless steel: DIN6923 DIN912 DIN603 DIN315,DIN933,DIN931,DIN934|
The material of high strength bolt is different from that of
ordinary bolt. High strength bolt is generally used for durable
connection. Commonly used are M16 / M30. The performance of super
high strength bolt is unstable. The bolted connections of the main
members of the building structure should be used with caution. High
strength bolts are generally used to connect. 5. High strength
bolts from the factory do not distinguish between bearing type and
friction type. 6. Whether it is friction type high strength hexagon
bolt and bearing high strength bolt. In fact, there are differences
in design and calculation methods: (1) friction type high strength
bolts take sliding between plates as the limit state of bearing
capacity.Sliding between as the normal use limit state, and joint
failure as the ultimate load capacity state. 7. Friction high
strength bolt can not give full play to the potential of the bolt.
In practical application. For very important structures or
structures subjected to dynamic loads, especially when the reverse
stress is caused by load, friction type high strength snails should
be used. The untapped bolt potential may be used as a safety
reserve at this time. In addition, high strength bearing bolts
should be used to reduce the cost.
High strength bolt connection has the advantages of simple
construction, good mechanical performance, detachability, fatigue
resistance, and no loosening under dynamic load. It is a promising
A high - strength bolt is a special wrench to tighten the nut , so
that the bolt generates a large and controlled pre - tension , and
the same size of pre - pressure is generated by the connecting
piece through the nut and the backing plate .
The high strength bolt connection depends on the friction between
the contact surfaces to prevent the joint from sliding, so as to
make the contact surface have enough friction. It is necessary to
increase the clamping force of the member and the friction
coefficient of the contact surface. The clamping force between the
components is realized by applying the pretension force to the
bolt, so the bolt must be made of high strength steel. This is also
known as high-strength bolt connections.
High strength bolt connection, greatly affect the size of the
coefficient of friction of bearing capacity. The results show that
the friction coefficient is mainly affected by the material form
and the effect of contact component. In order to increase the
friction coefficient of the contact surface, the construction
should be often used for sand blasting, to solve contact elements
in the area connecting surface with a wire brush cleaning method.