1. D ARSHAN INSTITUTE OF ENGINEERING & TECHNOLOGY

3. 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

4. 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 18-4-1 18% TUNGSTEN, 4% CHROMIUM, 1% VANADIUM. - M OLYBDENUM BASE IS KNOWN AS 6-6-4-2. 6% MOLYBDENUM, 6% TUNGSTEN, 4% CHROMIUM, 2% VANADIUM.

5. - 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.

6. 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 0.7-1.0% 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.

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

8. 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.

9. 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