Cover Page October-2018-Advanced Materials Letters

Advanced Materials Letters

Volume 9, Issue 10, Pages 677-683, October 2018
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The cover describes the development of nanofibers with encapsulated growth factors has been emerged as a promising approach in neo-tissues applications. The proposed nanofibrous systems provide a novel approach to both simulate the extra-cellular matrix for cell adhesion and also for localized delivery of signaling molecules and growth factors. Growth factors could be loaded into nanofibers using different techniques including physical adsorption, covalent bonding or encapsulation.


Hydrogen concentration behavior of y-grooved weld joint based on a coupled analysis of heat transfer - thermal stress - hydrogen diffusion

Go Ozeki1*, A. Toshimitsu Yokobori1, Toshihito Ohmi2, Tadashi Kasuya3, Nobuyuki Ishikawa4, Satoshi Minamoto5, Manabu Enoki

1Strategic Innovation and Research Center, Teikyo University, Tokyo, 173-8605, Japan

2Department of Mechanical Engineering, Shonan Institute of Technology, Kanagawa, 251-8511, Japan

3Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan

4Steel Research Laboratory, JFE Steel Corporation, Kanagawa, 210-8555, Japan

5Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, Ibaraki, 305-0047, Japan

Adv. Mater. Lett., 2018, 9 (10), pp 677-683

DOI: 10.5185/amlett.2018.2160

Publication Date (Web): Jul 18, 2018

E-mail: go.ozeki@med.teikyo-u.ac.jp

Abstract

It is important to predict the stress driven hydrogen induced cracking at the weld joint on the basis of computational mechanics from the view point of engineering problem. In this study, On the basis of proposed numerical analysis, behaviors of hydrogen diffusion and concentration during cooling process of y-grooved weld joint were analyzed and the mechanism of hydrogen induced cracking was investigated. One of authors has been proposed a multiplication method which magnifies the hydrogen driving term in the diffusion equation to realize correctly hydrogen concentration behaviors. In this study, the behaviors of hydrogen diffusion and concentration for the model of y-grooved weld joint was analyzed by combining a multiplication method with the coupled analyses of heat transfer – thermal stress – hydrogen diffusion. As a result, hydrogen was found to diffuse from weld metal to base metal through HAZ (Heat Affected Zone), and concentrate at the position of blunt angle side of weld groove bottom. It was found that hydrogen concentrates at the position of the local maximum value of hydrostatic stress gradient. This analytical result was found to well predict the actual hydrogen induced cracking of the y-grooved weld joint. Using this method of analysis, prediction of hydrogen induced cracking becomes possible. 

Keywords

Hydrogen diffusion, heat transfer, thermal stress, coupled analysis, y-grooved weld joint.

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