Analysis of formation and growth of the σ phase in additively manufactured functionally graded materials

Abstract This study focuses on the formation of the σ phase in three functionally graded material (FGM) systems made by additive manufacturing (AM): stainless steel 420 (SS420) to V to Ti–6Al–4V, Ti–6Al–4V to V to stainless steel 304 L (SS304L), and SS420 to V. Directly joining Ti–6Al–4V and stainless steel may result in the formation of brittle Fe–Ti intermetallics. This study investigates the potential use of V as an intermediate element between terminal alloys of Ti–6Al–4V and stainless steel. Experimental analysis of the elemental and phase composition revealed that different amounts of σ phase were present in the three FGM systems at locations with similar elemental compositions. Computational studies were performed to simulate the thermal history, phase transformation kinetics, and σ phase growth within these FGMs. The computations suggested that, at the conditions studied, the σ phase should nucleate faster and grow to a larger volume fraction in the SS420–V alloy than the SS304L–V alloy, contrasting with experimental observations. Instead, experimental analysis confirmed that the disparate growth of σ phase in the FGMs was due differences in cracking during fabrication, resulting in different amounts of time spent at the elevated temperatures conducive to σ phase growth in each of the samples.

[1]  Rolf Sandström,et al.  Sigma phase precipitation in duplex stainless steel 2205 , 2007 .

[2]  Zi-kui Liu,et al.  Experimental analysis and thermodynamic calculations of an additively manufactured functionally graded material of V to Invar 36 , 2018 .

[3]  Wei Li,et al.  Fabrication and Characterization of a Functionally Graded Material from Ti-6Al-4V to SS316 by Laser Metal Deposition , 2017 .

[4]  G. B. Kale,et al.  Interdiffusion studies in titanium–304 stainless steel system , 1998 .

[5]  A. K. Bhaduri,et al.  Joining of titanium to 304L stainless steel by friction welding , 2009 .

[6]  Christian Carpenter,et al.  Stainless steel to titanium bimetallic structure using LENS , 2015 .

[7]  Andrew A. Shapiro,et al.  Development and characterization of Ti-6Al-4V to 304L stainless steel gradient components fabricated with laser deposition additive manufacturing , 2016 .

[8]  Dominique Grevey,et al.  Dissimilar laser welding of AISI 316L stainless steel to Ti6–Al4–6V alloy via pure vanadium interlayer , 2015 .

[9]  B. Bilgin,et al.  Interfacial properties of diffusion bonded Ti-6Al-4V to AISI 304 stainless steel by inserting a Cu interlayer , 2009 .

[10]  Y. Ustinovshikov,et al.  Phase transformations in alloys of the Fe–V system , 2005 .

[11]  M. Hillert.  The compound energy formalism , 2001 .

[12]  Yefei Gao,et al.  Dissimilar Welding of Titanium Alloys to Steels , 2012 .

[13]  Mainak Ghosh,et al.  Characterization of transition joints of commercially pure titanium to 304 stainless steel , 2002 .

[14]  Andrew A. Shapiro,et al.  Characterization of a functionally graded material of Ti-6Al-4V to 304L stainless steel with an intermediate V section , 2018 .

[15]  Yi Wang,et al.  Computational Thermodynamics of Materials , 2016 .

[16]  Andrew A. Shapiro,et al.  Developing Gradient Metal Alloys through Radial Deposition Additive Manufacturing , 2014, Scientific Reports.

[17]  Hans Leo Lukas,et al.  Computational Thermodynamics: The Calphad Method , 2007 .

[18]  Andrew A. Shapiro,et al.  Additive manufacturing of a functionally graded material from Ti-6Al-4V to Invar: Experimental characterization and thermodynamic calculations , 2017 .

[19]  Esther T. Akinlabi,et al.  Functionally graded material: an overview , 2012, WCE 2012.

[20]  M. Balasubramanian.  Development of processing windows for diffusion bonding of Ti–6Al–4V titanium alloy and 304 stainless steel with silver as intermediate layer , 2015 .

[21]  J. Kim,et al.  Laser deposition additive manufacturing of 17-4PH stainless steel on Ti-6Al-4V using V interlayer , 2019, Materials Research Letters.

[22]  R. Wagner,et al.  Homogeneous Second‐Phase Precipitation , 2013 .

[23]  P. Michaleris,et al.  Thermomechanical model development and in situ experimental validation of the Laser Powder-Bed Fusion process , 2017 .

[24]  N. Saunders,et al.  CALPHAD : calculation of phase diagrams : a comprehensive guide , 1998 .

[25]  G. Burgess,et al.  The Emissivity of Metals and Oxides, II: Measurements with the Micropyrometer , 1914 .

[26]  William E. Frazier,et al.  Metal Additive Manufacturing: A Review , 2014, Journal of Materials Engineering and Performance.

[27]  S. Chatterjee,et al.  Evaluation of interface microstructure and mechanical properties of the diffusion bonded joints of Ti–6Al–4V alloy to micro-duplex stainless steel , 2011 .

[28]  Zi-kui Liu.  First-Principles Calculations and CALPHAD Modeling of Thermodynamics , 2009 .

[29]  J. Cieślak,et al.  Sigma-Phase in Fe-Cr and Fe-V Alloy Systems and its Physical Properties , 2011, 1105.2179.

[30]  M. Ghosh,et al.  Diffusion bonded transition joints of titanium to stainless steel with improved properties , 2003 .

[31]  B. Mishra,et al.  The effect of intermetallics on the strength properties of diffusion bonds formed between Ti–5.5Al–2.4V and 304 stainless steel , 2003 .

[32]  J. Smith.  The V (Vanadium) system , 1981 .

[33]  A. Bahrami,et al.  Sigma phase-induced failure of AISI 310 stainless steel radiant tubes , 2017 .