ISO7049 DIN7981 pan head Self tapping screws
This International Standard specifies the characteristics of Cross recessed pan head tapping screws with thread sizes from ST 2,2 to ST 9,5 inclusive.
Surface hardness:The minimum surface hardness after heat treatment shall be 450 HV 0,3
Core hardness:The core hardness af?er heat treatment shall be
270 HV 5 to 390 HV 5 for threads S ST3,9, and
270 HV 10 to 390 HV 10 for threads > ST4,2.
Self tapping screws torsional strength