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CHAPTER 5

POST HEAT TREATMENT TEST

This chapter will briefly mention about the results obtained in Tensile Test, Rockwell Hardness

Test, Chapy Impact Test and Microstructure, as in chapter 3, but of the specimens after heat

treatment i.e. annealing, normalizing and hardening.

5.1 Tensile Test

The tensile test for the heat treated specimens is conducted as mentioned in section 3.1 of chapter

3 for the heat treated specimens one by one, 3 specimens each for annealing, normalizing and

hardening, respectively. The following figures show the results and Load (Newton) v/s

Displacement (mm) of the heat treated specimens as mentioned below:

5.1.1 Results

5.1.1.1 Annealed Material

Sample 1

Fig. 5.1 Load v/s Displacement for Annealed Sample 1

-1000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 1 2 3 4 5 6 7

L o a d

( N )

Displacement (mm)

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Fig. 5.2 Results of Annealed Sample 1

Sample 2

Fig. 5.3 Load v/s Displacement for Annealed Sample 2

0

1000

2000

3000

4000

5000

6000

7000

0 1 2 3 4 5 6 7

L o a d

( N )

Displacement (mm)

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Fig. 5.4 Results of Annealed Sample 2

Sample 3

Fig. 5.5 Load v/s Displacement for Annealed Sample 3

0

1000

2000

3000

4000

5000

6000

0 1 2 3 4 5 6

L o a d

( N )

Displacement (mm)

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Fig. 5.6 Results for Annealed Sample 3

Normalized Material

Sample 1

0

1000

2000

3000

4000

5000

6000

7000

0 1 2 3 4 5 6

L o a d

( N )

Displacement (mm)

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Fig. 5.7 Load v/s Displacement for Normalized Sample 1

Fig. 5.8 Results for Normalized Sample 1

Sample 2

Fig. 5.9 Load v/s Displacement for Normalized Sample 2

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 1 2 3 4 5 6 7

L o a d

( N )

Displacement (mm)

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Fig. 5.10 Results for Normalized Sample 2

Sample 3

Fig. 5.11 Load v/s Displacement for Normalized Sample 3

0

1000

2000

3000

4000

5000

6000

7000

8000

0 1 2 3 4 5 6

L o a d

( N )

Displacement (mm)

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Fig. 5.12 Results of Normalized Sample 3

Hardened Material

Sample 1

Fig. 5.13 Load v/s Displacement for Hardened Sample 1

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 0.5 1 1.5 2 2.5

L o a d

( N )

Displacement (mm)

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Fig. 5.14 Results for Hardened Sample 1

Sample 2

Fig. 5.15 Load v/s Displacement for Hardened Sample 2

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 0.5 1 1.5 2 2.5 3 3.5 4

L o a d

( N )

Displacement (mm)

Load In N

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Fig. 5.16 Results for Hardened Sample 2

Sample 3

Fig. 5.17 Load v/s Displacement for Hardened Sample 3

-5000

0

5000

10000

15000

20000

0 1 2 3 4 5 6

L o a d

( N )

Displacement (mm)

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Fig. 5.18 Results for Hardened Sample 3

5.2 Rockwell Hardness Test

The hardness test for the heat treated specimens is conducted as mentioned in section 3.2 of

chapter 3 for the heat treated specimens one by one, 1 specimen each for annealing, normalizing

and hardening, respectively in the same manner as it has been done for the pre-heat treated

specimen. The following tables show the results of hardness obtained of the heat treated

specimens as mentioned below:

5.2.1 Results

5.2.1.1 Annealed specimen:

The RHN (C-scale) obtained at five different locations on the annealed specimen is given

in Table 5.1

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Table 5.1 RHN for annealed specimen

MATERIAL RHN

ANNEALED

C-79

C-85

C-85

C-80

C-89

5.2.1.2 Normalized specimen:

The RHN (C-scale) obtained at five different locations on the normalized specimen is

given in Table 5.2.

Table 5.2 RHN of normalized specimen

NORMALIZED

C-70

C-80

C-81

C-83

C-84

5.2.1.3 Hardened specimen:

The RHN (C-scale) obtained at five different locations on the hardened specimen is given

in Table 5.3.

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Table 5.3 RHN of hardened specimen

HARDENED

C-61

C-89

C-84

C-87

C-79

Average Hardness values of:

Annealed specimen : C-78 Normalized specimen : C-79.6 Hardened specimen : C-83.6

5.3 Charpy Impact Test

The Charpy Impact Test for the heat treated specimens is conducted as mentioned in section 3.3

of chapter 3 for the heat treated specimens one by one, 3 specimens each for annealing,

normalizing and hardening, respectively. The following tables show the results and impact

strength (in kg-m), of the heat treated specimens as mentioned below:

5.3.1 Results

5.3.1.1 Annealing

The obtained impact strength values in kg-m of the annealed specimens are as follows:

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Table 5.4 Impact Strength of Annealed Specimen

MaterialImpact Strength

(kg-m)

Annealed

4.4

5.8

7.0

5.3.1.2 Normalized Specimen

The obtained impact strength values in kg-m of the annealed specimens are as follows:

Table 5.5 Impact Strength of Normalized Specimen

Material Impact Strength

(kg-m)

Normalized

8.6

4.2

6.6

5.3.1.3 Hardened Specimen

The obtained impact strength values in kg-m of the annealed specimens are as follows:

Table 5.6 Impact Strength of Hardened Specimen

Material Impact Strength

(kg-m)

Hardened

7.8

7.6

7.2

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Impact strength of Annealed specimen : 5.73 kg.m

Impact strength of Normalized specimen : 6.46 kg.m

Impact strength of Hardened specimen : 7.53 kg.m

5.4 Microstructure

The microstructure study is conducted with the help of metallurgical microscope in the same

procedure as conducted for the pre heat treated specimen as mentioned in section 3.4 under

chapter 3. The results or the images obtained are as shown below with magnification 1000x:

5.4.1 Annealing

Figure 5.19 shows the microstructural image of an annealed En8 specimen.

\

Fig 5.19 Microstructure of Annealed Specimen

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5.4.2 Normalizing

Figure 5.20 shows the microstructural image of a normalized En8 specimen.

Fig 5.20 Microstructure of Normalized Specimen

5.4.3 Hardening

Figure 5.21 shows the microstructural image of a hardened En8 specimen.

Fig 5.21 Microstructure of Normalized Specimen