The effect of C and V content on hardness of non-quenched-tempered pre-hardening plastic die steel (/% : 0.36-0.45C
0.42-0.46Si
1.41-1.49Mn
0.11-0.15 V) has been tested and researched by a 50 kg medium frequency induction furnace in laboratory
and according to regression analysis the vanadium non-quenched-tempered prehardening plastic die steel 48MnV (/% : 0.45-0.50C
0.30-0.60Si
1.20-1.40Mn
≤0.020P
≤0.020S
0.15-0.20V) is developed to replace the quenched-tempered plastic die steel P20 (/% : 0.35-0.40C
0.40-0.60Si
0.80 -1.00Mn
≤0.015P
≤0.015S
1.50-1.80Cr
0.30-0.50Mo ). The production results of 110 heats commercial production by 120t BOF-360 mm x 450 mm casting-≤85 mm flat rolling-inline pre-hardening treated with controled cooling rate 0.6-1.0 °C/s flowsheet show that the HRC hardness value of non-quenched-tempered flat of steel 48MnV is 29.5-33.5 to meet the requirement of relative specificalion.