Title: Investigation of dissimilar metal welds by energy-resolved neutron imaging

Abstract

A nondestructive study of the internal structure and compositional gradient of dissimilar metal-alloy welds through energy-resolved neutron imaging is described in this paper. The ability of neutrons to penetrate thick metal objects (up to several cm) provides a unique possibility to examine samples which are opaque to other conventional techniques. The presence of Bragg edges in the measured neutron transmission spectra can be used to characterize the internal residual strain within the samples and some microstructural features, e.g. texture within the grains, while neutron resonance absorption provides the possibility to map the degree of uniformity in mixing of the participating alloys and intermetallic formation within the welds. In addition, voids and other defects can be revealed by the variation of neutron attenuation across the samples. This paper demonstrates the potential of neutron energy-resolved imaging to measure all these characteristics simultaneously in a single experiment with sub-mm spatial resolution. Two dissimilar alloy welds are used in this study: Al autogenously laser welded to steel, and Ti gas metal arc welded (GMAW) to stainless steel using Cu as a filler alloy. The cold metal transfer variant of the GMAW process was used in joining the Ti to the stainless steel in ordermore » to minimize the heat input. The distributions of the lattice parameter and texture variation in these welds as well as the presence of voids and defects in the melt region are mapped across the welds. The depth of the thermal front in the Al–steel weld is clearly resolved and could be used to optimize the welding process. As a result, a highly textured structure is revealed in the Ti to stainless steel joint where copper was used as a filler wire. The limited diffusion of Ti into the weld region is also verified by the resonance absorption.« less

Authors:

Tremsin, Anton S. ^[1]; Ganguly, Supriyo ^[2]; Meco, Sonia M. ^[2]; Pardal, Goncalo R. ^[2]; Shinohara, Takenao ^[3]; Feller, W. Bruce ^[4]

---

+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States)
2. Cranfield Univ., Bedfordshire (England)
3. Japan Atomic Energy Agency, Ibaraki (Japan)
4. NOVA Scientific, Inc., Sturbridge, MA (United States)

Publication Date:

Thu Jun 09 00:00:00 EDT 2016

Research Org.:

NOVA Scientific, Inc., Sturbridge, MA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1434911

Grant/Contract Number:  

FG02-07ER86322

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Crystallography (Online)

Additional Journal Information:

Journal Name: Journal of Applied Crystallography (Online); Journal Volume: 49; Journal Issue: 4; Journal ID: ISSN 1600-5767

Publisher:

International Union of Crystallography

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; nondestructive testing; laser welding; dissimilar joining; microstructure; neutron imaging