The level of the lifting hook depends on the mechanical properties of the finished lifting hook.
The weights and grades are rated, and the rated weight and test load are specified in the four types of lifting hooks, respectively, with letters M, P, S, and T.
The basic design load of the lifting hook is equal to the test load (Fe).
The requirements of M, P, S and T on steel:
1) steel shall be made from the furnace, electric furnace and oxygen at the top of the converter.
2) steel should be composed steel, which can be forged well. After proper heat treatment, it can meet the mechanical properties stipulated in the standard.
3) when the steel is tested according to YB/T5148, the grain size of the austenitic number 5 or finer grade shall be reached.