For inspection, whether it is slender or elongated, it is qualified as long as it can meet the testing standards of steel bars of this grade in the laboratory! !

Informal method:

1, use a ruler or caliper to measure the diameter, but this is based on experience, and the diameters of steel bars produced by different factories are different (within the allowable range).

2, visual inspection, slimming mainly depends on "pull" and "pull", sometimes too thin, there will be obvious drawing marks or cracks on the surface of steel bars;

3. Try bending. As mentioned above, slimming mainly depends on "pulling" and "pulling", which has little effect on the strength of steel bars, but increases the hardness and brittleness, so simply bend it with a steel bar processing machine (according to the grade of steel bars, don't try to bend a hook of 180 with grade III steel).