Quenching and tempering, Mechanical Engineering

Quenching and Tempering

Cast iron pearlite structure might be heated to lower critical temperature and after that quenched to effect extremely rapid cooling. This treatment reasons the precipitation of hard martensite phase and casting is hence capable of giving high wear resistance. The casting behind quenching treatment might be further heated to 300oC and cooled gradually to restore original toughness.

Surface Hardening

A lot of applications of cast iron demand high surface hardness. This might be attained by surface hardening treatments as like: induction and nitriding hardening.

Table: Typical Mechanical Properties and Applications of Cast Iron

 

Cast Iron

Composition wt. %

Condition

Structure

UTS MPa

YS MPa

Elongation

(%)

Typical Application

 

 

Gray Cast

Iron

Ferrite

3.4 C,

2.2 Si,

0.7 Mn

Annealed

Ferrite matrix

180

-

-

Cylinder blocks and head clutch plates

Pearlite

3.2 C,

2.0 Si,

0.7 Mn

As-cast

Pearlite matrix

250

-

-

Truck and tractor cylinder blocks, gear box

Pearlite

3.3 C,

2.2 Si,

0.7 Mn

As-cast

Pearlite matrix

290

-

-

Diesel engine castings

 

 

Melleable

Cast Iron

Ferrite

2.2 C,

1.2 Si,

0.75 Mn

Annealed

Temper carbon and ferrite

345

224

10

General engineering service machinability

Pearlite

2.4 C,

1.4 Si,

0.75 Mn

Annealed

Temper carbon and pearlite

440

310

8

General service with dimensional tolerance

Martensitic

2.4 C,

1.4 Si,

0.75 Mn

Quenched and Tempered

Tempered martenstie

620

438

2

High strength parts, connecting rods, yokes for universal joints

 

 

Ductile

Cast Iron

Ferrite

3.5 C,

2.2 Si

Annealed

Ferritic

415

275

10

Pressure casting as valve and pump bodies

Pearlite

3.5 C,

2.2 Si

As-cast

Ferritic pearlite

550

380

6

Crank shaft, gears and rollers

Martensitic

3.5 C,

2.2 Si,

Quenched and Tempered

Martensitic

830

620

2

Pinions, gears, rollers and slides

 

 

Posted Date: 2/26/2013 6:59:23 AM | Location : United States







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