PSI - Issue 2_A

Abhishek Tiwari et al. / Procedia Structural Integrity 2 (2016) 690–696 Author name / Structural Integrity Procedia 00 (2016) 000–000

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Using Eq. (4), the transformed data at 0.5 a/W were analyzed using MC method as shown in Fig. 6.

Fig. 6 Master Curve plot of all K JC transformed to a/W = 0.5.

5. Conclusion Master Curve fracture toughness analysis was carried out on 0.2T specimen in the range of 0.2 to 0.7 a/W . The dataset were categorized based on a/W and analysed for reference transition temperature determination. The T 0 was found to be increasing with deeper crack depth. The numerical analysis showed that under non-SSY stress field condition for both constraint loss and high constraint specimens the active volume scaling with K JC changes drastically and cannot be analysed using conventional Master Curve method. On the other hand in the range of 0.37 ≤ a/W ≤ 0.54, the data can be analysed using Master Curve by transforming the dataset to a single a/W scale. The numerical analysis of active volume ahead of crack front showed a good correlation with change in T stress . The fitting parameters Z´ was found to follow one on one correlation with Δ T stress and therefore this parameter can be used as a measure of constraint for cleavage fracture. The new constraint parameter q W was investigated for different crack depth models and correlated with standard constraint parameter T stress . The constraint was found to be captured more accurately by Weibull triaxiality in comparison with fitting parameters of K JC -V* behaviour. ASTM E1921-13a, 2014. Standard Test Method for Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range, ASTM International, West Conshohocken, PA, www.astm.org Bhowmik S, Sahoo P, Acharyya SK, Dhar S, Chattopadhyay J, 2015. Evaluation and effect of loss of constraint on master curve reference temperature of 20MnMoNi55 steel. Engineering Fracture Mechanics. 136:142-57. Chen Z-A, Zeng Z, Chao YJ, 2007. Effect of crack depth on the shift of the ductile-brittle transition curve of steels. Engineering Fracture Mechanics 74:2437. Laha K, Saroja S, Moitra A, Sandhya R, Mathew MD, Jayakumar T, Rajendra Kumar E, 2015. Development of India-specific RAFM steel through optimization of tungsten and tantalum contents for better combination of impact, tensile, low cycle fatigue and creep properties. Journal of Nuclear Materials;439:41. Tiwari A, Avinash G, Sunil S, Singh RN, Ståhle P, Chattopadhyay J, et al., 2015. Determination of reference transition temperature of In RAFMS in ductile brittle transition regime using numerically corrected Master Curve approach. Engineering Fracture Mechanics. 142:79-92. Wallin K, 1999. The master curve method: a new concept for brittle fracture. International Journal of Materials and Product Technology 14, 342 54 Wallin K, 2011. Quantifying Tstress controlled constraint by the master curve transition temperature T0. Engineering Fracture Mechanics. 68:303-28. References