Identifying the authenticity of high strength bolts
Identify High Strength Bolts is also skilled, generally in this industry for a long time, you will learn the skill, the following is for everyone to sort out some of the knowledge.
1. Identification
There are obvious strength grade marks on the package of bolts manufactured by regular manufacturers. Such as 8.8, 10.9 and 12.9. More important is to do a good job in the selection of purchasing channels and the authority of the third-party experimental institutions.
2. Hardness
Generally speaking, the grade of hexagon socket bolts is relatively high. The reason is that the hexagon hole of hexagon socket bolts can only be used after heat treatment. The materials that can improve the hardness after treatment are quenched and tempered steel, which has high mechanical strength after quenching and tempering;
3. Hue
High strength bolts without galvanizing are generally black. The black outer layer is an oxide layer formed by artificial processing, which is called blackening in industry. It is a protective layer formed by corrosion of strong alkaline substances on metal surface, which can resist oxidation. DOWEDO has always been committed to the production and service of professional bolt products. The bolts produced by the company are not only beautiful in appearance, but also guaranteed in quality. Therefore, high strength bolts are generally not rusty!
4. Sound
The simplest empirical judgment: throw it to the ground, listen to the sound, and the high-strength sound is brittle. If the sound is bright, it is strip steel. In the scratch test with saw blade and other hard tools, the surface hardness of high-strength bolts is larger than that of ordinary bolts.
5. Quenching and tempering
For the problem of quenching and tempering, the general high-strength material is grade 8.8, and some manufacturers may not quench and temper it, and sell it to customers as grade 12.9 or grade 10.9. The way to distinguish it is to see that in the sun, the hair that is not quenched and tempered is dark, and the one that has been tempered is colored. This is the most basic common sense.
The five methods listed above can be used to identify the authenticity of high strength bolts.
A relevant point worth mentioning
What is considered a high strength bolt?
Typical high tensile bolts include: Grade 8.8 bolts: Usually constructed of steel and coated with multiple layers, structural grade bolts are another name for them. Grade 10.9 fasteners: These bolts are often known as “car bolts” because the automotive industry uses them the most.