Effect of Tellurium on Processing Performance of 40Cr13 Plastic Mold Steel

Milling, drilling and polishing tests were carried out on tellurium-free low-sulfur（0.003wt% sulfur）40Cr13 steel with hardness of 41, 38, 36 HRC, tellurium-containing medium-sulfur（0.003wt% tellurium, 0.022wt% sulfur）40Cr13 steel with hardness of 41 HRC, and tellurium-free high-sulfur（0.070wt% sulfur）40Cr13 steel with hardness of 33, 41 HRC. The morphology and microhardness of inclusions were analyzed, and the effect of tellurium on the processing performance of the test steel was studied. The results show that compared with those in tellurium-free low-sulfur steel, the inclusions in tellurium-containing medium-sulfur steel were mainly MnS, whose size increased and aspect ratio was almost unchanged, and the inclusions were mostly ellipsoids. The inclusions in the tellurium-free high-sulfur steel were mainly MnS, and whose number, size and aspect ratio all increased, and the inclusions were long strip. The microhardness of sulfides in tellurium-containing medium-sulfur steel increased because of the solid solution of tellurium in sulfides. When the hardness was constant, the milling force, drilling force and surface roughness after milling of tellurium-containing medium-sulfur steel were smaller than those of the tellurium-free low-sulfur, and the cutting performance was better. The surface roughness after polishing of the tellurium-containing medium-sulfur steel was bigger than that of the tellurium-containing medium-sulfur steel, and the polishing performance was slightly worse.