National standard angle steel: take the steel bar as an example; the thickness of the national standard is 40 "40" 4 50 "50" 5 tolerance is 6% (that is, less than 6 points).
Other angle steel with thin thickness is defined as non-standard angle steel.
National standard angle steel.
However, it is not considered that the non-standard angle steel is of inferior quality, and the lower deviation of the non-standard angle steel produced by some large factories is normally controlled within a certain range, such as 40-40-40-3-angle steel 50-50-4 angle steel, which is of good quality and is widely used.
Non-standard angle steel.
Note: non-standard angle steel processed by some small factories,
Most of the materials are uneven and have many impurities, and the carbon content is generally relatively high, so the surface is hard, the plasticity is not good, and the force is easy to break and the deviation cannot be controlled within a certain range, so it is not suitable to be used in key parts and major parts. in addition, it is generally not recommended to use this kind of steel 40 "40" 4 angle steel in mass production, non-standard may be 38 "39" 3.5 "36" 37 "3.0 38" 35 "3.2, all can be seen.
There is no way to control the quality of the product.