Weldability of Ti-6Al-4V Alloys Formed via Various Powder Consolidation Techniques

Abstract:

This study considers the weldability of Ti-6Al-4V alloys formed by various powder consolidation methods. Samples were prepared from commercially sourced pre-alloyed Ti-6Al-4V powder using both conventional press-and-sinter (PS) and the new novel resistance-heated pressing (RHP) methods. Fusion welding was executed by the gas tungsten arc (GTA) process with arc stability assessed in-situ by observations of the arc as well as monitoring of transient arc voltage. Results indicated equivalent arc stability between samples of RHP and commercially sourced wrought material while samples formed by PS showed high instability in arc initiation, attributed to high levels of porosity. Post weld analysis of mechanical hardness in powder based samples revealed no significant deviation in weld metal properties from welds conducted on commercially sourced wrought material. In all cases weld microstructures typical of Ti-6Al-4V alloys were observed with significant grain growth in the fusion and heat affected zones. Samples prepared by PS methods showed internal porosity due to gas evolution upon solidification, which may again be attributed to the highly porous initial microstructure.

• Periodical: Key Engineering Materials (Volume 520)
• Pages: 314-319
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.520.314
• Online since: August 2012
• Authors: Nicholas Hoye, Hui Jun Li, John Norrish, Rian J. Dippenaar, Ali Dehghan-Manshadi
• Keywords: Direct Manufacture, Fusion Welding, Powder Processing, Sintering, Ti6Al4V

References

[1] E. Kraft, Summary of Emerging Titanium Cost Reduction Technologies, (EHK Technologies-for ORNL, Vancouver, WA, 2004), 1-59.

[2] S. Seong, O. Younossi, B.W. Goldsmith, Titanium: Industrial Base, Price Trends, and Technology Initiatives, RAND Corporation, Santa Monica, California, (2009).

DOI: 10.7249/mg789

[3] B.E. Hurless, F.H. Froes, Lowering the Cost of Titanium, The AMPTIAC Quarterly, 6 (2002) 3-9.

[4] R.J. Low, I.M. Robertson, M. Qian, G.B. Schaffer, Sintering of titanium powder compacts for containerless hot isostatic pressing, Materials Science Forum, 618-619 (2009) 509-509-512.

DOI: 10.4028/www.scientific.net/msf.618-619.509

[5] G. Lutjering, J.C. Williams, Titanium, (Springer, 2007), pp.86-115.

[6] D. McCue, B. Irving, Gast Tungsten Arc Welding: It's Built to Handle Titanium, Welding Journal, 70 (1991) 31-36.

[7] RMI, Titanium Alloy Guide, (RTI International Metals Inc, 2004), 10-15.

[8] W.T. Machines. www. welding-technology-machines. info/physics-of-welding/arc-stability. htm. cited November 11; (2011).

[9] A. Sanchez Roca, H. Carvajal Fals, J. Blanco Fernandez, F. Sanz Adan, E. Jimenez Macias, Stability analysis of the gas metal arc welding process based on acoustic emission technique, Welding International, 23 (2009) 173-173-180.

DOI: 10.1080/09507110802543385

[10] M. Suban, J. Tušek, Methods for the determination of arc stability, Journal of Materials Processing Technology, 143-144 (2003) 430-437.

DOI: 10.1016/s0924-0136(03)00416-3

[11] Struers, B. Taylor, E. Weidmann, Application Notes - Metallographic Preparation of Titanium, (Struers, 2009), 1-6.