On the Role of the Process Zone in Hydrogen Assisted Cracking-II. Kinetic Conditions

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Department of Mechanical Engineering-Engineering Mechanics


Following up the developments of recent work on the geometric and force characteristics of the process zone (PZ) and its role on environmental fracture we discuss here the problem of hydrogen assisted cracking (HAC) in elastoplastic material under kinetic conditions. The analysis is based on the postulate that cracking proceeds in step-wise fashion with an average velocity determined by the ratio Δa/Δtc, where Δa is an average crack jump length and Δtc the time interval between two subsequent jumps. Since Δa has been calculated in our earlier work with the aid of macroscopic considerations, emphasis is put here on the calculation of Δtc by considering the critical accumulation of hydrogen within the PZ. Indeed, this is used to formulate a chemomechanical type fracture criterion which eventually leads to the prediction of velocity vs stress intensity factor graphs. © 1988.

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© 1988

Publication Title

Engineering Fracture Mechanics