in the stamping die, it refers to the mold steels with low hardness in HRC35 and low hardness, such as 45# steel, A3, Q235, etc.You with a slightly higher hardness on the above, you can knock out a hole to come out, this kind of material is very soft, so used to call "soft", because of its seismic performance is good, generally used to make stamping die and mold base plate, bottom shoes, up and down.
Hard material: in the stamping die, is refers to the hardness after heat treatment () around HRC58-62 or more steel material, such as: Cr12, Cr12Mo1v1, Cr12Mov, Skd - 51, Skd - 11, W6Mo5Cr4V2 (tungsten steel), the steel material hardness is very high (but also more brittle, a bit not note may be you will crash, 55), commonly used for edge of stamping die, punch, or other parts of high hardness required.