CHAPTER 6 : HEAT TREATMENT OF STEEL

sub- chapter 6

HEAT TREATMENT

OF STEEL

PREPARED BY : MUHAMAD SYAFIQ BIN ZAINUN , POLITEKNIK BANTING SELANGOR

Start

lesson plan

01

02

03

04

RECAP PREVIOUS CHAPTER

LECTURE ON CURRENT TOPIC

QUIZIZZ GAME

LAB BRIEFING

lesson outcome

1. UNDERSTAND THE CYCLE / STAGES OF HEAT TREATMENT 2. UNDERSTAND PROCESS OF ANNEALING, NORMALIZING AND QUENCHING 3. UNDERSTAND THE EFFECT OF HEAT TREATMENT PROCESS

example:heat treatment of gear

why? to increase hardness of gear teeth

DEFINITION

"controlled heating and cooling of metals to alter their mechanical properties without changing the product’s shape"

WHY HEAT TREATMENT MUST BE DONE ?

during metal fabrication process, grain structures compressed, distorted and elongated. This causes the material properties of metals change, especially mechanical properties, such as its hardness, ductility, brittleness and so on

EXAMPLE

EFFECT OF COLD WORK ON TO GRAIN STRUCTURE

purpose of heat treatment

CYCLE / STAGES OF HEAT TREATMENT

ANIMATION VIDEO OF HEAT TREATMENT (WATCH TILL 3:40)

changes in microstructure in annealing process

comparison

QUENCHING

NORMALIZING

changes in microstructure in normalizing process

changes in microstructure in quenching process

HEAT TREATMENT process & ITS EFFECT

QUENCHING

NORMALIZING

ANNEALING

NORMAL COOLING RATE Produce medium degree of strength, ductility, softness, hardness.

FAST COOLING RATE Increase hardness, strength, brittleness. Decrease ductility, machining, softness.

SLOW COOLING RATE Refine grain, increase ductility, machining, softness. Decrease hardness, strength, brittleness

¡muchas gracias!