... mirror electro-polish Specification1, investment casting ,precision casting2, carbon steel / alloy steel /stainless steel3, SDM/OEM4, FIMA , AP,QP,QA,QC ... ,corrosion resistance ,and surface treatment .unless otherwise indicated ,all alloy steels are quoted with a normalize or anneal All 300 ... are listed from least to greatest cost1) Carbon and low Alloy steels 8620,4140,1020,1035,are best choices.2) ...