materials

Question 1

TOOL STEELS

Answer 1

e high quality steels made to controlled chemical composition and
processed to develop properties useful for working and shaping of other materials

The Carbon content is between 0.1 - 1.6%. Tool steel also contain alloying elements like:
Chromium, Molybdenum and Vanadium

Question 2

water hardened tools

Answer 2

These are indicated by the symbol W

➢ Characteristics:
* High tensile strength & hardness levels
but low ductility & toughness values.
* Very poor hardenability

Question 3

heating of water hardened

Answer 3

Typical Heat Treating Process consists of:
A) PREHEATING the Annealed tool, typically at 670 oC.
B) AUSTENITIZING (Soaking at High Heat).
C) QUENCHING – Quench to Hard Brittle (Martensite) condition.
D) TEMPERING or ANNEALING (Drawing to desired hardness).

Question 4

what does Cr and V do?
for water hardened

Answer 4

Presence of Cr Inhibits pearlite formation and therefore
increases hardness & hardenability: (the ability of the
material to form martensite)
➢ Vanadium is often added to inhibit grain growth when
austenitzing, this works by forming V4C3 which then pins
the grain boundaries, increasing hardness, improving
wear resistance.

Question 5

SHOCK-RESISTING TOOL STEELS (S

Answer 5

S7 Characteristics
1.High Impact Resistance
2.Excellent Toughness at high Strength levels
3.Good Wear Resistance
4.High Hardenability & Softening Resistance

Question 6

s7 heat treatment

Answer 6

1.Annealing
* Heating slowly and uniformly to 815 ~ 845℃,
* furnace cooling to 510℃ at a rate 8 ~ 15℃ / hr.
2.Stress Relieving
* Warming to 650℃, furnace cooling.
3.Hardening
* Preheating: Warming to approx. 650 ~ 700℃, holding 20 minutes
per 25 mm.
* Austenitizing: Heating to approx. 925 ~ 960℃, holding 20 minutes
per 25 mm.
* Quenchant: By oil
4.Tempering
* 150~200℃, holding 30 minutes per 25 mm. Air-cooling. Hardness
min. HRc 56
20

Question 7

cold worked steels

Answer 7

air, oil, water
Generally characterized by high abrasion & wear resistance,
higher toughness and high impact resistance

Question 8

oil hardened steels

Answer 8

Characterized by:
* high as-quenched hardness; high
machinability, low red hardness.
* high hardenability and they resist
cracking on quenching

Question 9

three times of hot worked steels

Answer 9

Chromium-based
Tungsten-based

Molybdenum-based

Question 10

hot worked characterised

Answer 10

Characterised by resistance to:
1. Deformation at Hot Working Temperatures
2. Mechanical and Thermal Shock (this is helped by keeping the carbon
content low)
3. Wear and Erosion
4. Deformation during Heat Treatment
5. Heat Checking

Question 11

Chromium based [H11- H19] hot worked?-

Answer 11

Contains Chromium (>=3.25%
applications :-
Hot dies for extrusion,
forging, mandrels, punches.
* Highly stressed structural
parts of supersonic aircrafts.
* Hot work steels.

Question 12

tungsten based hot worked ?

Answer 12

Contains tungsten (9.00%) & Chromium (2.0 - 12.0%), and low Carbon %.
Applications:
➢ Punches, Mandrels, Extrusion dies for
Brass, Steel & Nickel alloys.

Question 13

MOLYBDENUM BASED hot wokred

Answer 13

Contains Molybdenum (8.00%)
& Chromium (4.0 -12.0%), and
some tungsten and Vanadium.

Question 14

molybdenum character

Answer 14

➢ These are characterized by high
toughness & high heat check
resistance.