TOOL STEELS

• TOOL STEELS are high quality steels made to controlled chemical composition and processed to develop properties useful for working and shaping of other materials.

• These are used in applications such as Blanking, die forging, forming, extrusion and plastic molding etc..

TYPES

• SHOCK-RESISTING TOOL STEELS• COLD-WORKED TOOL STEELS• HOT-WORKED TOOL STEELS• HIGH-SPEED TOOL STEELS• WATER-HARDENED TOOL STEELS

SHOCK-RESISTING TOOL STEELS

• These are characterized by good toughness, hardness and improved hardenability. These steels are generally, water or oil- hardened.

• “Low temperature Tempering” is carried out where, toughness and hardness of the tool steel are of prime importance, otherwise “High temperature Tempering” is preferred.

APPLICATIONS:

– Punches– Shear blades– Scarring Tools– River sets – Driver bits.

HOT-WORKED TOOL STEELS

• These are characterized by high hot yield strength, high red hardness , wear resistance, toughness, erosion resistance, resistance to softening at elevated temperatures, good thermal conductivity

COLD-WORKED TOOL STEELS

• These steels are used for making tools for cold work applications, when the tool surface temperature does not rise more than 200°c.

• These are characterized by high abrasion & wear resistance, higher toughness and high impact resistance.

Microstructure of As-Tempered COLD WORK

TOOL STEEL (1000x)

COINING DIES

EXPANSION REAMERS

HIGH SPEED TOOL STEELS

• These are high alloyed tool steels developed initially to do high speed metal cutting. Now, they used in a wide variety of machining operations.

• They contain 0.6 % carbon, 4% Chromium, 5-12% Cobalt.

• Applications : • End mills, drills, lathe tools, planar tools. • Punches, reamers, • Routers, taps, saws. • Broaches, chasers, and hobs.

Microstructure of oil- quenched HSS (500x)

MILL CUTTERS

Microstructure of oil- quenched

18-4-1 type HSS

WATER-HARDENED TOOL STEELS

• These steels contain carbon in the range of 0.9-1.0% along with Cr, V, Mo.

• These are characterized by high tensile strength & hardness levels but low ductility & toughness values.

• Tempering temperatures are in the range 170-220°C.

Applications :

• Heavy forging hammers, hand hammers. • Forging dies, bending dies, cutting dies.• Large blanking tools, boring tools.• Chisels, scissors, knife blades.• Milling cutters, lathe centre.• Watch maker’s tools.• Engraving tools.

ENGRAVING TOOL

WATCH MAKER’S TOOLS

DRILL ROD OF W1 TOOL STEEL

CAST IRON

• Cast Iron is generally defined as an alloy of Iron with 2 to 4.5% Carbon, and usually with more than 0.1% Silicon

• The three main ingredients are – Iron– Carbon– Silicone

• Cast iron containing more of these materials than steel.

Types of Cast Iron

• Grey cast iron - carbon as graphite

• White cast iron – carbides

• Ductile cast iron

• Malleable cast iron

Grey Cast Iron

• Graphite flakes surrounded by a matrix of either Pearlite or -a Ferrite

• Graphite flakes surrounded by a matrix of either Pearlite or -a Ferrite

• Wide range of applications• Low ductility• Grey cast iron forms when– Cooling is slow, as in heavy sections

Grey Cast Iron

Applications

• Engines• Pressure pipe fittings• Machinery beds• Furnace parts

White Cast Iron

• No graphite, because carbon forms Fe3C or more complex carbides

• Large amount of carbide phases in the form of flakes, surrounded by a matrix of Pearlite

• The absence of graphite causes white iron's light-colored appearance

White Cast Iron

Applications

• Stairs• Decorative features• Tools and utensils

Ductile Iron

• Inoculation with Mg causes graphite to form as spherulites, rather than flakes

• Also known as spheroidal graphite (SG).

• Far better ductility than grey cast iron

Ductile Iron

Applications

• Automotive industry 55% of ductile iron used

– Crankshafts

– front wheel spindle supports

– steering ; disc brake callipers

• Pipe and pipe fittings (joined by welding)

Malleable Iron

• Graphite in nodular form

• Produced by heat treatment of white cast iron

• Graphite nodules are irregular clusters

• Similar properties to ductile iron

Malleable Iron

Applications

• Similar applications to ductile iron

• Malleable iron is better for thinner castings

• Vehicle components

• Railway components

• Pipe fittings