Abstract
Punching die steel is now most widely used in mechanical and electrical industries, chiefly to punch thin Si-plates, mild steel plates, etc. Many kinds of punching die steel are commonly used today, and their compositions are mainly of high carbon, low Mn-Cr-W and high carbon Cr system. The authors carried out a series of experiments on the effects of C 0.8∼1.3%Mn 0.7∼1.2% and Cr 3.0∼7.0% on the properties of die steels of standard composition, C 1.1 and Cr 5.0%, of which the transformation points were measured and changes in their hardness and microstructures brought out by different heat treatments were studied. We also measured the rate of deformation due to various heat treatment. The results of these experiments are summarized as follows: (1) The A1 and Ar″ transformation point drop with the increase of the C and Mn contents, but Cr shows the inverse results. (2) The quenching temperature necessary for the maximum hardness is lowered with the increase of the C and Mn contents, but Cr shows the inverse results. (3) The rate of deformation due to heat treatment decreases when the C, Mn and Cr contents increase.
