Impact of localized surface preheating on the microstructure and crack formation in laser direct deposition of Stellite 1 on AISI 4340 steel

Abstract Crack formation in laser cladding of the hardfacing alloy Stellite 1 on AISI-SAE 4340 steel was prevented through locally preheating the substrate prior to the deposition process. Numerical analysis showed that the preheating process helps developing a relatively steadier melt temperature as well as decreasing the cooling rates and consequently the thermal stresses during the subsequent deposition process. Microstructural analysis revealed a thicker cross-section with smoother surface profile, more uniform surface hardness and even distribution of a dendritic morphology in the preheated sample. This confirmed the presence of a well-developed melt pool with a homogeneous composition at solidification. The microstructure of non-preheated sample was, however, considerably non-uniform consisting of macro-scale colonies of dendritic and lamellar (eutectic) structures. The experimental observations, as implied through the numerical results, showed that the preheated sample, in general, reveals more uniform structure and properties making it less prone to cracking during the deposition process.

[1]  R. Fabbro,et al.  Analytical and numerical modelling of the direct metal deposition laser process , 2008 .

[2]  K. O’Grady,et al.  柔軟記録媒体のための金属粒子(MP)技術の開発 , 2008 .

[3]  Huan Qi,et al.  Numerical simulation of heat transfer and fluid flow in coaxial laser cladding process for direct metal deposition , 2006 .

[4]  J. D. Hosson,et al.  Microstructure and abrasive wear of cobalt-based laser coatings , 1997 .

[5]  N. Dahotre,et al.  Laser surface cladding of MRI 153M magnesium alloy with (Al+Al2O3) , 2009 .

[6]  E. Toyserkani,et al.  On the delamination and crack formation in a thin wall fabricated using laser solid freeform fabrication process: An experimental-numerical investigation , 2009 .

[7]  C Rinaldi,et al.  Epitaxial repair and in situ damage assessment for turbine blades , 2005 .

[8]  Wilfried Kurz,et al.  High speed laser cladding: solidification conditions and microstructure of a cobalt-based alloy , 1993 .

[9]  A. M. Deus,et al.  Rapid tooling by laser powder deposition : Process simulation using finite element analysis , 2005 .

[10]  K. Antony.  Wear-Resistant Cobalt-Base Alloys , 1983 .

[11]  G. Śliwiński,et al.  Temperature distribution in laser-clad multi-layers , 2004 .

[12]  E. Toyserkani,et al.  A 3D dynamic numerical approach for temperature and thermal stress distributions in multilayer laser solid freeform fabrication process , 2007 .

[13]  G. Śliwiński,et al.  Investigation of temperature and stress fields in laser cladded coatings , 2007 .

[14]  Cobalt based alloy PTA hardfacing on different substrate steels , 2005 .

[15]  M. Okayasu,et al.  Etching technique for revelation of plastic deformation zone in low carbon steel , 2005 .

[16]  E. Toyserkani,et al.  The effect of localized dynamic surface preheating in laser cladding of Stellite 1 , 2010 .

[17]  B. Luan,et al.  Protective coatings on magnesium and its alloys — a critical review , 2002 .

[18]  Helen L. W. Chan,et al.  Enhanced dielectric properties of highly (100)-oriented Ba(Zr,Ti)O₃ thin films grown on La[sub 0.7]Sr[sub 0.3]MnO₃ bottom layer , 2006 .

[19]  J. Choi,et al.  Three-dimensional transient finite element analysis for residual stresses in the laser aided direct metal/material deposition process , 2005 .

[20]  Luca Giordano,et al.  Laser stellite coatings on austenitic stainless steels , 1987 .

[21]  F. Cardarelli.  Materials Handbook — a concise desktop reference: Pub 2000, ISBN 1-85233-168-2. 595 pages, £80 , 2001 .

[22]  W. Kurz,et al.  Microstructural effects on the sliding wear resistance of a cobalt-based alloy , 1994 .