PSI - Issue 14

S Usha Rani et al. / Procedia Structural Integrity 14 (2019) 142–149 Author name / Structural Integrity Procedia 00 (2018) 000–000

148

7

be seen that the difference in hardness between runs using temperature 400°C at 30 minutes is much greater than the difference in hardness between runs using temperature at 450°C and 500°C at 15 and 60 minutes.

Table.4: Response Table for means and Sound-to-Noise (S-N) ratio.

Levels

Response for Means

Response for S-N ratio

Temperature

Time 38.27 38.37 36.67

Temperature

Time 31.62 31.59 31.24

1 2 3

42.70 38.00 32.60 10.10

32.60 31.59 30.26

Delta Rank

1.70

2.35

0.38

1

2

1

2

3.4. Analysis of variance The Analysis of Variance (ANOVA) is used to investigate the influence of tempering parameters on performance characteristics. The percentage contribution of each parameter is calculated and the percentage contribution to the overall performance is determined using Fisher’s test (J. Lin and C. Lin (2002)). The Table.5 represents the ANOVA analysis for grey relational grade. The percentage contribution for tempering temperature is significant than tempering time. From the ANOVA analysis, it can be concluded that the tempering temperature has greater contribution of 75.12% to the overall performance.

Table.5: ANOVA for Grey relational grade.

Source

Degree of freedom (D.O.F)

Sum of Squares (SS)

Means of squares (MS)

Fisher value (F)

Level of significance (P)

Percentage contribution (ρ)

Temperature

2 2 2 8

0.80842 0.40420 0.10663 0.05331 0.16104 0.04026 1.07609 0.49777

10.04

0.028 0.362

75.14

Time Error Total

1.32

9.90

- -

- -

14.96

100

3.5 Fatigue testing For the purpose of testing, one of the arms of ASB was welded with end lug. It is a displacement-controlled test with ±21.15 mm displacement. A stress level of 40% and 30% of UTS which is 545MPa and 408 MPa respectively was applied. The fatigue test was performed using Instron servo hydraulic linear actuator. The failure occurred in the highly stressed region which was observed near the bent zone. The Table 6 represents fatigue life of the component tested at two different stress levels. Table 6. Fatigue test results (trial 2). Stress Level (MPa) Number of cycles 545 (0.4 of UTS) 46940 408 (0.3 of UTS) 215902 4. Conclusion In this present work, grey relation-based Taguchi method was used to study the best tempering parameter for 26MnB5 martensitic steel. The results are summarized as follows:

 Considering the grey relational grade, main effect and interaction effect, trial 2 is optimized.