There are significant differences between high-strength bolts and ordinary bolts in many aspects, which are mainly reflected in raw materials, strength levels, stress characteristics, application scenarios and reusability.
First, raw materials and manufacturing process
High strength bolt: its screw, nut and washer are made of high strength materials, such as 45 steel, 40 boron steel and so on. After heat treatment, these materials have high strength and good toughness.
Ordinary bolts: Usually made of Q235 steel, this material is relatively low in strength, but the cost is also more economical.
Second, intensity level
High strength bolt: high strength grade, commonly used 8.8 and 10.9, of which 10.9 is the most widely used. High-strength bolts can withstand greater loads and are suitable for occasions where the connection strength is required to be higher.
Ordinary bolts: The strength level is low, and the common ones are 4.4, 4.8 and 5.6. These bolts are suitable for applications where connection strength is not required.
Third, the force characteristics
High-strength bolt: In the force, in addition to relying on the strength of the material itself, it can also generate extrusion pressure between the connecting components by applying pre-tension, thereby increasing the friction of the screw. This mode of force makes the high-strength bolts can withstand greater external loads, and have better shear and anti-slip properties.
Ordinary bolts: mainly rely on the rod and hole wall to bear the force. The pre-tension generated when tightening the nut is small, and its effect is negligible. Therefore, the shear resistance of ordinary bolts is relatively poor.
Fourth, application scenarios
High strength bolts: used for Bridges, rail, high pressure and ultra-high pressure equipment connection need to bear large loads and high safety requirements. Due to the non-reusability of high-strength bolts, they are often used for permanent connections.
Ordinary bolts: are widely used in machinery manufacturing, construction, automobiles, electronics, aviation and other fields. They can be used to connect various machine tools, agricultural machinery, railway vehicles, mechanical and electrical equipment, etc., and can also be used to fix steel structures, Bridges, buildings, etc. Ordinary bolts can be reused and are suitable for occasions that require frequent disassembly or temporary connection.
Fifth, reusability
High strength bolt: Because it will produce a large pre-tension during the tightening process, resulting in greater thread wear between the bolt and the nut, it is generally not recommended to reuse.
Ordinary bolt: Because its tightening pre-tension is small, thread wear is relatively small, so it can be reused many times.
Sixth, other differences
Friction type and pressure type: high strength bolts are also divided into friction type and pressure type two. Friction type high-strength bolts are mainly used in situations where dynamic loads need to be borne or sliding needs to be strictly controlled. The pressure type high-strength bolts allow relative slip deformation between the connectors, which is suitable for static loads or situations where a certain slip is allowed.
Construction and maintenance: high-strength bolt connection has the advantages of simple construction, good mechanical performance, fatigue resistance, etc., but the pre-tension needs to be strictly controlled during use to ensure the quality of the connection. Ordinary bolts are easier to construct, but regular inspection and maintenance are needed to ensure the safety of the connection.
In summary, there are significant differences between high-strength bolts and ordinary bolts in terms of raw materials, strength grades, stress characteristics, application scenarios and reusability. When choosing which bolt to use, it needs to be considered according to the specific working conditions and requirements.
