PSI - Issue 2_B

Satoshi Igi / Structural Integrity Procedia 00 (2016) 000–000

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Satoshi Igi et al. / Procedia Structural Integrity 2 (2016) 1601–1609

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4.2. Effect of cyclic strain Comparison between monotonic and cyclic pre-straining on Charpy transition curve using SM490A steel were summarized in Fig. 11. The change of the Charpy transition temperature shift quantity by the total amount of pre strain which taking into account of skeleton stain in the case of cyclic pre-strain. As shown in Fig. 11, cyclic pre-strain can be evaluated equally with the monotonic pre-strain by the total amount of pre-strain.

Fig. 11. Comparison of test result between monotonic and cyclic loading

5. Conclusion The fracture toughness value for structural steels at an evaluation temperature T (minimum service temperature) under pre-strain and dynamic loading conditions can be replaced by the static fracture toughness value for virgin steels (without pre-strain) at the reference temperature T - Δ T PD (Fig. 1 ). The temperature shift Δ T PD is given by the following equation as a function of the ch ange Δ σ f PD in flow stress from static and non pre-strain conditions. In addition, it is examined the influence of the dynamic and pre-strain history on fracture toughness change for HT780 and confirmed that a temperature shift equations in WES2808 (2003) can be applicable to HT780 steel. These results will be included to the next revision of WES2808. The Δ T PD above is a temperature shift at the level where the critical CTOD ≈ 0.10 mm. A larger temperature shift is estimated at a higher level of critical CTOD (conservative evaluation). Acknowledgements The authors wish to acknowledge support and permission to publish this paper provided by Iron & Steel Division of Japan Welding Engineering Society. References The Japan Welding Engineering Society, 2003. Method of Assessing Brittle Fracture in Steel Weldments Subjected to Large Cyclic and Dynamic Strain, WES 2808. (in Japanese) The Japan Welding Engineering Society, Iron and Steel division, APD committee, 1996. Strength and Fracture Toughness of Welded Connection of Steel Structure for Buildings Subjected to Large-Scale Cyclic Deformation (Interim Report III), JWES-IS-9603. (in Japanese) Hidaka, S., Nakagomi, T., Yamada, T. and Oobayashi, I., 1995. Experimental Study on Fracture Behavior of Welded Connection and Deterioration of Mechanical Properties , Summaries of Technical Papers of Annual Meeting Architectural Institute of Japan, No222166-22168. (in Japanese).     ≤ ∆ ≤ PD f σ ≤ ∆ ≤ PD f σ ∆ ∆ = T PD ) 300( / 40 :100 ) 100( / : 0 0.4 2 2 N mm N mm PD f σ