Controlling the microstructure and properties of wire arc additive manufactured Ti–6Al–4V with trace boron additions

Abstract This study demonstrates that trace boron addition to Ti–6Al–4V coupons produced by additive layer manufacturing is an effective way to eliminate the deleterious anisotropic microstructures often encountered with this manufacturing technique. Trace boron additions (up to 0.13 wt.%) to this alloy eliminate grain boundary-α and colony-α, and instead produce a homogeneous α-microstructure consisting of fine equiaxed α-grains in both as-deposited and heat treated coupons. Prior-β grains remain columnar with boron addition but become narrower due to the wider solidification range and growth restricting effect of the boron solute. Compared to unmodified Ti–6Al–4V alloy, Ti–6Al–4V modified with trace boron additions showed up to 40% improvement in plasticity with no loss in strength under uniaxial compression at room temperature. Boron additions were found to inhibit twinning transmission that causes sudden large load drops during deformation of the unmodified Ti–6Al–4V alloy in the heat treated condition.

[1]  W. Soboyejo,et al.  Tensile deformation and fracture behaviour of a titanium-alloy metal-matrix composite , 1997 .

[2]  P. Colegrove,et al.  Microstructure and Mechanical Properties of Wire and Arc Additive Manufactured Ti-6Al-4V , 2013, Metallurgical and Materials Transactions A.

[3]  H. Fraser,et al.  Laser deposition of compositionally graded titanium–vanadium and titanium–molybdenum alloys , 2003 .

[4]  David W. Rosen,et al.  Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing , 2009 .

[5]  Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties , 2012 .

[6]  Konrad Wissenbach,et al.  Ductility of a Ti‐6Al‐4V alloy produced by selective laser melting of prealloyed powders , 2010 .

[7]  Philip B. Prangnell,et al.  Effect of build geometry on the β-grain structure and texture in additive manufacture of Ti6Al4V by selective electron beam melting , 2013 .

[8]  B. Baufeld,et al.  Additive manufacturing of Ti–6Al–4V components by shaped metal deposition: Microstructure and mechanical properties , 2010 .

[9]  Stewart Williams,et al.  Morphology investigation on direct current pulsed gas tungsten arc welded additive layer manufactured Ti6Al4V alloy , 2011 .

[10]  D. StJohn,et al.  The Interdependence Theory: The relationship between grain formation and nucleant selection , 2011 .

[11]  H. Fraser,et al.  Formation of equiaxed alpha in TiB reinforced Ti alloy composites , 2005 .

[12]  Xibing Gong,et al.  Beam speed effects on Ti–6Al–4V microstructures in electron beam additive manufacturing , 2014 .

[13]  岡本 博明,et al.  Desk handbook phase diagrams for binary alloys , 2000 .

[14]  Xinhua Wu,et al.  Direct laser fabrication and microstructure of a burn-resistant Ti alloy , 2002 .

[15]  Matthew S. Dargusch,et al.  Grain-refinement mechanisms in titanium alloys , 2008 .

[16]  S. Kelly,et al.  Microstructural evolution in laser-deposited multilayer Ti-6Al-4V builds: Part I. Microstructural characterization , 2004 .

[17]  I. R. Pashby,et al.  Deposition of Ti–6Al–4V using a high power diode laser and wire, Part II: Investigation on the mechanical properties , 2008 .

[18]  G. Lütjering.  Influence of processing on microstructure and mechanical properties of (α+β) titanium alloys , 1998 .

[19]  R. Srinivasan,et al.  Development of solidification microstructure in boron-modified alloy Ti-6Al-4V-0.1B , 2011 .

[20]  Bernd Baufeld,et al.  Mechanical properties of Ti-6Al-4V specimens produced by shaped metal deposition , 2009, Science and technology of advanced materials.

[21]  T. Velikanova,et al.  Effect of boron on the structure and mechanical properties of Ti–6Al and Ti–6Al–4V , 2005 .

[22]  S. S. Al-Bermani,et al.  The Origin of Microstructural Diversity, Texture, and Mechanical Properties in Electron Beam Melted Ti-6Al-4V , 2010 .

[23]  M. Preuss,et al.  Deformation twinning in Ti-6Al-4V during low strain rate deformation to moderate strains at room temperature , 2010 .

[24]  D. StJohn,et al.  The effect of boron on the refinement of microstructure in cast cobalt alloys , 2011 .

[25]  Jing Liang,et al.  Microstructures of laser-deposited Ti–6Al–4V , 2004 .

[26]  James C. Williams,et al.  Perspectives on Titanium Science and Technology , 2013 .

[27]  Mariana Calin,et al.  Selective laser melting of in situ titanium–titanium boride composites: Processing, microstructure and mechanical properties , 2014 .

[28]  U. Ramamurty,et al.  Microstructural effects on the mechanical behavior of B-modified Ti–6Al–4V alloys , 2007 .

[29]  F. H. Sam Froes,et al.  Cost-affordable titanium: The component fabrication perspective , 2007 .

[30]  R. Poprawe,et al.  Laser additive manufacturing of metallic components: materials, processes and mechanisms , 2012 .

[31]  Christoph Leyens,et al.  Additive manufactured Ti-6Al-4V using welding wire: comparison of laser and arc beam deposition and evaluation with respect to aerospace material specifications , 2010 .

[32]  Lijun Song,et al.  Fabrication of Ti-6Al-4V Scaffolds by Direct Metal Deposition , 2008 .

[33]  A. Wisbey,et al.  Laser-aided manufacturing technologies; their application to the near-net shape forming of a high-strength titanium alloy , 2005 .

[34]  C. Liu,et al.  Improved ductility and oxidation resistance of cast Ti–6Al–4V alloys by microalloying , 2014 .

[35]  C. M. Ward-Close,et al.  Titanium Particulate Metal Matrix Composites – Reinforcement, Production Methods, and Mechanical Properties , 2000 .

[36]  S. L. Semiatin,et al.  The effect of laser power and traverse speed on microstructure, porosity, and build height in laser-deposited Ti-6Al-4V , 2000 .

[37]  D. StJohn,et al.  Beryllium as a grain refiner in titanium alloys , 2009 .

[38]  Peter C. Collins,et al.  Nanoscale TiB precipitates in laser deposited Ti-matrix composites , 2005 .

[39]  J. Mei,et al.  Direct laser fabrication of Ti6Al4V/TiB , 2008 .

[40]  Peter C. Collins,et al.  Direct laser deposition of in situ Ti–6Al–4V–TiB composites , 2003 .

[41]  H. Fraser,et al.  Structure of TiB precipitates in laser deposited in situ, Ti-6Al-4V–TiB composites , 2006 .

[42]  Robert E. Reed-Hill,et al.  Physical Metallurgy Principles , 1972 .

[43]  K. Ray,et al.  Crystallographic orientation relationships of boride and carbide particles with α and β phases in a β-Ti alloy , 2014 .

[44]  M. Bermingham,et al.  Titanium as an endogenous grain-refining nucleus , 2010 .

[45]  D. StJohn,et al.  A model of grain refinement incorporating alloy constitution and potency of heterogeneous nucleant particles , 2001 .

[46]  C. M. Ward-Close,et al.  Microstructure and tensile properties of mechanically alloyed Ti–6A1–4V with boron additions , 2000 .

[47]  Paul A. Colegrove,et al.  Investigation of the benefits of plasma deposition for the additive layer manufacture of Ti–6Al–4V , 2012 .

[48]  He Yang,et al.  Solidification Behavior and the Evolution of Phase in Laser Rapid Forming of Graded Ti6Al4V-Rene88DT Alloy , 2007 .

[49]  Y. F. Yang,et al.  Modification of the α-Ti laths to near equiaxed α-Ti grains in as-sintered titanium and titanium alloys by a small addition of boron , 2013 .

[50]  Christoph Leyens,et al.  Morphology, microstructure, and hardness of titanium (Ti-6Al-4V) blocks deposited by wire-feed additive layer manufacturing (ALM) , 2012 .

[51]  K. Chandran,et al.  TiBw-reinforced Ti composites: Processing, properties, application prospects, and research needs , 2004 .

[52]  S. Emura,et al.  Reinforcing effect of in situ grown TiB fibers on Ti-22Al-11Nb-4Mo alloy , 2000 .

[53]  M. Bermingham,et al.  Effects of boron on microstructure in cast titanium alloys , 2008 .