Download or read book Dynamic Fracture Toughness Characterization of HY-100 Under-Matched Welds written by Stephen M. Graham and published by . This book was released on 2000-02-01 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Welds in marine structures are typically fabricated such that the yield strength of the weld metal is higher than the base plate (over-matched). Allowing the weld metal yield strength to be less than the base metal (under- matching) can increase productivity and weld metal toughness; however, there is some concern that under-matching increases the crack driving force and decreases the weld metal tearing resistance. This study examined fracture behavior of two HY-100 under-matched welds under dynamic loading. A new test fixture that provided greater control of specimen deflection during impact testing of SE(B) specimens was developed, as was a procedure for applying the Normalization Method to the analysis of dynamic fracture toughness tests. Successful application of Normalization involved using multiple specimens with varying ductile crack growth to establish the correct form for the plasticity function. The accuracy of the measured J(sub Id) was verified by comparing with multi- specimen J(sub Id) values. The results from these tests showed that the proximity of the crack tip to the fusion line had more effect on fracture behavior than mismatch level. Narrower fusion line margins led to lower tearing resistance and a greater propensity for fracture instability.