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Microstructure and Mechanical Properties of Laser Beam Welded Joints between Fine‐Grained and Standard Ti‐6Al‐4V Sheets Subjected to Superplastic Forming
Author(s) -
Kashaev Nikolai,
Ventzke Volker,
Horstmann Manfred,
Riekehr Stefan,
Yashin Grigory,
Stutz Lennart,
Beck Werner
Publication year - 2015
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201400202
Subject(s) - materials science , welding , superplasticity , microstructure , laser beam welding , butt joint , metallurgy , composite material , heat affected zone , ultimate tensile strength , butt welding
A fine‐grained Ti–6Al–4V sheet that has been developed for superplastic forming (SPF) was joined to a standard Ti–6Al–4V sheet using a Nd:YAG laser and alloy compatible filler wire. The microstructural and mechanical properties of dissimilar laser beam welded butt joints were investigated to determine their behavior under static and cyclic loads and for SPF. The filler wire affected the heat input and reduced the increase in the hardness within the fusion zone compared to that in the heat‐affected zone. The laser beam welding process activated local microstructure transformations that were associated with local changes in the microtexture, the β content, and the grain size. The mechanical behavior of a dissimilar laser beam welded butt joint under a static tensile load was controlled by the properties of the standard Ti–6Al–4V sheet. Laser beam welded specimens showed inferior fatigue behavior. Removing the geometrical notches did not significantly improve the fatigue behavior because local microstructural and microtextural changes still created metallurgical notches. SPF was observed in the fine‐grained Ti–6Al–4V sheet without crack formation in the heat‐affected zones or the fusion zone. The welding seam of the dissimilar fine‐grained‐standard butt joint was resistant to SPF.