TO study HEAT AFFECTED ZONE of low carbon steel(Mild steel), Micro-structure observation of heat affected zone of mild steel, Hardness test done of mild steel at their different zones. at the result we find out that the HAZ zone grain was more coarser than base metal and HAZ zone. due to sudden cooling at fusion zone micro structure columnar form which increase the hardness at that zone much more.

1. MICROSTRUCTURE
OBSERVATION
OF
HEAT AFFECTED ZONE
MUKESH KUMAR
YOGESH KUMAR
PIYUSH VERMA
SIDDARTH THAKUR
FIROJ MAHATO YOGENDRA KUMAR

2. CONTENT
1) PROJECT GOAL
2) SELECTION OF SPECIMEN
3) PREPARATION FOR SEEING MICROSTRUCTURE OF
SPECIMEN
4) MICROSTRUCTURE OBSERVATION
5) HARDNESS TEST
6) PREPARED FOR WELD
7) AFTER WELDING PROCESS OBSERVATION
8) FINAL MICROSTRUCTURE AFTER WELDING
9) HARDNESS TEST AFTER WELD
10) CONCLUSION

3. PROJECT GOAL
Our project research to base metal (mild steel) changes in microstructure and
mechanical property changes due to welding (fusion zone) and due to heat
affected zone.

4. MILD STEEL
mild steel is one of type of the carbon steel (plain carbon).which generally consist
carbon content up to 0.025-0.3%.
PROPERTY OF MILD STEEL
 Mild steel is very strong due to the low amount of carbon it contain
Mild steel has a high resistance to breakage.
It has high tensile and impact strength
High carbon steel usually shatter or crack under stress while mild steel bends or deforms.
SELECTION OF SPECIMEN
We are selected mild steel plate which have 120 mm length, 4.5mm thickness .
Some typical composition and property of mild steel contain which are discuss below :-

5. 1. PREPARATION FOR SEEING
MICROSTRUCTURE OF SPECIMEN-
Metallography consists of the microscopic study of the structural characteristic of
a metal or an alloy. Metallography is the general study of metal and their behavior,
with particular reference to their macro and micro structure.
the steps involved are-
a. Cutting
b. Mounting
c. Grinding
d. Polishing
e. Etching
nital(5% nitric acid+95% Alcohol)

6. MICROSTRUCTURE OBSERVATION
OPTICAL MICROSCOPE
Optical microscope is type of equipment which is used
for seeing the microstructure of metal or alloy.
Working principle -All using the principle of examination by
the reflection of light from the specimen surface.
A metallurgical microscope helps determining:-
-- Grain size and shape.
-- Size, shape and distribution of various phase
-- Inclusion.
-- Mechanical and thermal treatment of the alloys.

7. MICROSTRUCTURE OF MILD STEEL – FERRITE+PEARLITE
OBSERVATION OF THE MICROSTRUCTURE

8. ROCKWELL HARDNESS TESTING
Rockwell Hardness is probably the most used
hardness testing method because it is simple and self
contained
The indenter is either a "spheroconical" diamond
(called "Brale") shaped in conical form, with an
included angle of 120 degrees and with a smoothly
rounded tip of 0.2 mm radius, or a hardened ball
of one of a range of different diameters (1/16",
1/8", 1/4", 1/2").
HARDNESS TEST
ROCKWELL CUM BRINELL
HARDNESS TESTING M/C
Load/time 100kg/6sec 100kg/6sec 100kg/6sec
HRC 14 13 14
*Average hardness -14HRC

9. PREPARED FOR WELD
Welding is a fabrication or sculptural process that joins materials,
usually metals or thermoplastics, by causing fusion, which is distinct from lower temperature
metal-joining techniques
Arc welding: - Arc welding is a process that is used to join metal to metal by using
electricity to create enough heat to melt metal, and the melted metals when cool result
in a binding of the metals. It is a type of welding that uses a welding power supply to
create an electric arc between an electrode and the base material to melt the metals at
the welding point.

10. AFTER WELDING PROCESS OBSERVATION
After specimen its need surface
cleaning of the specimen weld
bead for further process(e.g.
microstructure & hardness
observation).
Cause of uneven weld bead.
-- now again hole process
doing (e.g. metallography
and hardness testing).
1-2
3-4
5

11. HEAT AFFECTED ZONE
WELD ZONE
BASE METAL
FINAL MICROSTRUCTURE AFTER WELDING

12. Welded zone
Load 100kg 100kg 100kg
HRC 19 20 19
Heat affected zone
Load 100kg 100kg 100kg
HRC 16 14 16
*Average hardness – 14
*Average hardness – 15
*Average hardness – 19
HARDNESS TEST AFTER WELD
Base Metal
Load 100kg 100kg 100kg
HRC 14 14 16

13. CONCLUSION
Remark point concluded by our project discussion, in microstructure
observation – due to time and cooling recrystallization take place.
- grain growth.
Through hardness test- increased hardness in base metal different zone due to
heat and time of cooling.

14. THANK YOU