EFFECT OF CRYOGENIC COOLING RATE ON THE TOOL STEELS PROPERTIES

Andrey Rabin ¹ Andrey Rabin ¹ Gedalia Mazor ² Roni Z. Shneck ¹ Alex Shapiro ² Itzhak Ladizhenski ²

¹Materials Engineering, Ben Gurion University of th eNegev, Beer Sheva, Israel
²Mechanical Engineering, Shamon College of Engineering, Beer Sheva, Israel

Evaluation of the effect a high cooling rate to cryogenic temperatures (by immersing the material in liquid nitrogen with saturation temperature of -195.7ºC) on the mechanical properties of different types of the tool steels: AISI D-2 high carbon and high chromium cold work steel, AISI O1 oil-hardening cold work steel and AISI H13 chromium hot work steel. Variation of the cooling rate was achieved by addition of different coatings by spraying a solution of magnesium sulfate-MgSO4·7H2O, dried foams or detergents and by frost layers.
The HV microhardness and the wear rate under dry abrasive friction were investigated after quenching. The rapid cryogenic cooling improves both the hardness and the wear resistance values of the three steels. For all investigated metals the rapid cryogenic cooling assisted with the frost layer produces the best results. Increasing of the maximal cooling rate by 4 times led to reducing of the steel wear rate by factor 2.
Further research of higher outflow heat flux and of the optimal heat treatment sequence including rapid cryogenic cooling may improve the lifespan and reliability of cutting inserts made of the tool steels.