D ARSHAN INSTITUTE OF ENGINEERING & TECHNOLOGY

C LASSIFICATION OF TOOL STEEL : 1. A CCORDING TO QUENCHING MEDIA A. WATER HARDENING STEEL B. O IL HARDENING STEEL C. AIR HARDENING STEEL 2. A CCORDING TO ALLOY CONTENT A. CARBON TOOL STEEL B. LOW ALLOY TOOL STEEL C. MEDIUM ALLOY TOOL STEEL

3. A CCORDING TO APPLICATION A. H OT WORK STEEL B. S HOCK RESISTING STEEL C. H IGH SPEED STEEL D. COLD WORK STEEL O THER T YPES 1. M OLYBDENUM BASE (G ROUP M). 2. T UNGSTEN BASE (G ROUP T). - T UNGSTEN BASE IS KNOWN AS % TUNGSTEN, 4% CHROMIUM, 1% VANADIUM. - M OLYBDENUM BASE IS KNOWN AS % MOLYBDENUM, 6% TUNGSTEN, 4% CHROMIUM, 2% VANADIUM.

- M OLYBDENUM STEEL IS LOWER IN PRICE, SO OVER 80% OF H.S.S. IS PRODUCED OF MOLYBDENUM TYPE STEEL. - W HEN BETTER THAN AVERAGE RED HARDNESS IS REQUIRED, STEEL CONTAINING COBALT IS RECOMMENDED. - H IGHER VANADIUM CONTENT IS DESIRABLE WHEN THE MATERIAL CUT IS HIGHLY ABRASIVE. - I N T-15 STEEL, A COMBINATION OF COBALT AND VANADIUM PROVIDES RED HARDNESS AND ABRASION RESISTANCE.

High speed tool steel :  These steels are the most highly alloyed of the tool steel usually contain large amount of tungsten or molybdenum along with chromium, vanadium and Sometimes cobalt. Carbon content varies from % and sometimes up to 1.5%.  Application of high speed steel is for cutting tools also they are used for making extrusion dies, burnishing tools and blanking punches and dies.

P HASE D IAGRAM OF H IGH -S PEED S TEELS

P ROPERTIES : -E XCELLENT RED HARDNESS ( TOOL CAN OPERATE AT HIGH TEMPERATURE.) - G OOD SHOCK RESISTANCE. - G OOD NON DEFORMING PROPERTIES. - G OOD WEAR RESISTANCE. - F AIR MACHINABILITY. - F AIR TO POOR RESISTANCE TO DECARBURIZATION.

A PPLICATION : - C UTTING TOOL LIKE DRILL, TAPE REAMER ETC. ( MULTI CUTTING TOOL ). - S HEARING TOOL USE FOR SHEAR, PUNCH AND BLANKING DIE. - D RAWING AND EXTRUSION DIE. - T HREAD ROLLING DIE. - S INGLE CUTTING TOOL IN LATHE AND PLANNING MACHINE