Steel sample was annealed, normalized and hardened using in various temperatures and time. The process details and other details can be found here easily.

1. Design of Annealing, Normalizing and Hardening Heat
Treatment of Steel and Tempering of Hardened Steel to get
75% of the Hardness of that of as Quenched Steel
Presented by:
Md. Musavvir Mahmud
ID: 201111006
Department of Materials and Metallurgical Engineering,
BUET

2. SPECIMEN TO HEAT TREAT
 Round steel rod
 Diameter: 12 mm
 Sample given: 5

3. ANALYSIS OF NON TREATED SAMPLES
 Small samples (.5 inch) were cut for further analysis
 Grinded with grinding machine
 Carried out following analyses:
 Chemical composition analysis
 Metallographic analysis
 Hardness measurement

4. CHEMICAL COMPOSITION ANALYSIS
 Polished with 120 grade emery paper.
 Analysis was carried out by Optical Emission Spectroscopy (OES)
Element Fe C Si Mn P S Cu Ni
Wt % 98.262 0.31009 0.07975 1.1112 0.02542 0.0222 0.06235 0
Element Cr Al V Mo N B Nb Ti
Wt % .05999 0.03716 0 0 0.02735 0.00116 0 0.00105

5. METALLOGRAPHIC ANALYSIS
 Polished with different grades of emery papers
 Grades of papers: 180, 320, 600, 800, 1200
 Wet polished
 Etched with 2% Nital

6. METALLOGRAPHIC ANALYSIS_ctd
Figure: Microstructure of non treated specimen consisting of ferrite and perlite
grains etched in 2% nital, 500x zoom

7. HARDNESS MEASUREMENT
90.167 88.230 89.241 90.267 89.980
 Carried out in Rockwell B scale with 100 kg load
 Hardness values:
Average hardness= 89.567

8. ANNEALING

9. ANNEALING TEMPERATURE AND SOAKING TIME
 First upper critical temperature was calculated with following formula:
 A3 (OC) = 910 – 203(%C) – 15.2(%Ni) + 44.7(%Si) + 104(%V) + 31.5 (%Mo)
= 910- 203X0.31009 – 0 + 44.7X0.07975 + 0 + 0
= 850.62 OC
 For full annealing 40 OC was added.
 So annealing temperature = (850.62 + 40) OC
= 890.62 OC
 20 min per cm of thick section
 So soaking time= 20*1.2
= 24 min

10. PROBLEMS FACED AND OVERCOMING
 Sample was not annealed at the calculated temperature
 Annealing was carried out by trail and error basis
 Annealing was achieved at 950C soaking for 2 hours
 Samples were prepared as before for following tests:
 Metallography Analysis
 Hardness Measurement
 Chemical Composition Analysis

11. METALLOGRAPHIC ANALYSIS
 Sample was prepared by polishing with different grades of emery paper along
with wet polishing. Then etched in 2% Nital.
Figure: Microstructure of annealed specimen consisting of large ferrite and
perlite grains etched in 2% nital, 500x zoom

12. HARDNESS MEASUREMENT
91.8 90.0 86.5 91.4 87.1 90.0
 Carried out in Rockwell B scale with 100 kg load
 Hardness values:
Average hardness= 89.467

13. CHEMICAL COMPOSITION ANALYSIS
 Polished with 120 grade emery paper.
 Analysis was carried out by Optical Emission Spectroscopy (OES)
Element Fe C Si Mn P S Cu Ni
Wt % 97.969 0.32089 0.13898 1.3530 0.03463 0.01999 0.10169 0
Element Cr Al V Mo N Nb Ti
Wt % 0.05438 0.00729 0 0 0 0 0

14. NORMALIZING

15. NORMALZING TEMPERATURE AND SOAKING TIME
 Normalizing Temperature was selected = (850.62+60)C
= 910.62C
 Soaking Time =(60+D) [ D=diameter in mm]
=(60+12) min
= 72 min

16. PROBLEMS FACED AND OVERCOMING
 Sample was not normalized at the calculated temperature
 Normalizing was carried out by trail and error basis
 At 950C it was failed again
 Normalizing was achieved at 1000C soaking for two hours
 Samples were prepared as before for following tests:
 Metallographic Analysis
 Hardness Measurement
 Chemical Composition Analysis

17. METALLOGRAPHIC ANALYSIS
 Sample was prepared by polishing with different grades of emery paper along
with wet polishing. Then etched in 2% Nital.
Figure: Microstructure of normalized specimen grains etched in 2% nital, 500x
zoom

18. HARDNESS MEASUREMENT
94.6 102.0 94.0 99.1 100.6
 Carried out in Rockwell B scale with 100 kg load
 Hardness values:
Average hardness= 98.06

19. CHEMICAL COMPOSITION ANALYSIS
 Polished with 120 grade emery paper.
 Analysis was carried out by Optical Emission Spectroscopy (OES)
Element Fe C Si Mn P S Cu Ni
Wt % 98.085 0.19484 0.13487 1.3667 0.02941 0.01919 0.10365 0
Element Cr Al V Mo N Nb Ti
Wt % 0.05542 0.01059 0 0 0 0 0

20. HARDENING

21. CARBON EQUIVALENT
 Calculated with the following formula:
 𝐶𝐸 =
𝐶+𝑀𝑛
5
+
𝐶𝑟
4
+
𝑀𝑜
3
+
𝑁𝑖
10
+
𝑉
5
+
𝑆𝑖 −0.5
5
+
𝑇𝑖
5
+
𝑊
10
+
𝐴𝑙
10
=
0.31009+1.1112
5
+
0.05999
4
+
0.07975−0.5
5
+
0.00105
5
= 0.2154
 As CE≤0.4, sample is not sensitive to heating rate

22. TEMPERATURE AND HOLDING TIME
 Hardening temperature was selected as the same of
annealing, 950C
 Heating rate is fixed in the furnace of lab, 0.13C/s
 From the graph, hardening time is taken as 90 minutes

24. QUENCHING
 Sample was rapidly cooled in iced brine water
 Following tests were carried out for hardening samples:
 Metallographic analysis
 Hardness measurement

25. METALLOGRAPHIC ANALYSIS
 Sample was prepared by polishing with different grades of emery paper along
with wet polishing. Then etched in 2% Nital.
Figure: Microstructure of hardened specimen grains etched in 2% nital
consisting of martensite and retained austenite, 500x zoom

26. HARDNESS MEASUREMENT
45 48.5 52.7 52.2 51.1 42.0
 Carried out in Rockwell C scale with 150 kg load
 Hardness values:
Average hardness= 48.2
Formation of martensite has increased the hardness significantly.

27. HARDNESS REQUIRED FOR TEMPERING
 As required, 75% of hardened steel
 So hardness needed= 48.2X0.75
= 36.2 HRC

28. TEMPERING

29. TEMPERATURE AND TIME
 From the graph temperature is=
535C for 2 hours 40 minutes
 Holding for much time decreased
hardness too much
 Holding for 15 minutes at 535
yielded almost required hardness

30. METALLOGRAPHIC ANALYSIS
 Sample was prepared by polishing with different grades of emery paper along
with wet polishing. Then etched in 2% Nital.
Figure: Microstructure of tempered specimen grains etched in 2% nital
consisting of martensite, ferrite and cementite, 500x zoom

31. HARDNESS MEASUREMENT
31.6 38.1 37.9 38.2 38.2
 Carried out in Rockwell C scale with 150 kg load
 Hardness values:
Average hardness= 36.8
Percentage= 36.8/48.2X100%
= 76.24%