From

Development of RSM Model in Surface Modification of EN-31 Die Steel Material Using Copper-Tungsten Powder Metallurgy Semi-Sintered Electrodes by EDM Process

H. S. Sidhu, S. S. Banwait, S. C. Laroiya

American Journal of Mechanical Engineering. 2013, 1(6), 155-160 doi:10.12691/ajme-1-6-2