Influence of cooling speed on the microstructure and wear behaviour of hypereutectic Fe–Cr–C hardfacings

Abstract The main focus of this work is to show influences of the cooling rate on the microstructure and wear performance of Fe–Cr–C hardfacings. The coatings were produced by welding. The weld overlays were cooled from the molten stage in selected variations: (i) standard cooling – cooling on air at the steel welding table; (ii) passive cooling – cooling of the base material during the hardfacing process with a water cooled cooper plate with 12 °C; (iii) active cooling – cooling of the welding seam behind the main arc with CO 2 gas at temperature of −80 °C. For each cooling situation the temperature of the weld seam was measured in the melt pool with help of thermocouple. It was shown, that different cooling conditions can lead to the significant changes in the cooling-off time t 8/5 , dilution of the hardfacing with substrate and microstructural features of the hardfacings under investigation. Three different wear tests (three-body abrasion according to ASTM G65 standard, impact/abrasion and solid particle erosion) were performed to study the wear performances of Fe–Cr–C hardfacing. Testing results have shown that if the cooling-off time t 8/5 is too short it influences the brittleness and increases the residual stresses of the Fe–Cr–C hardfacing, which lowers its impact resistance. The effect of the cooling rate is in good correlation with wear test results and gives promise for further microstructure and process optimisation for the improved tribological performance.

[1]  A. Neville,et al.  Erosion–corrosion degradation mechanisms of Fe–Cr–C and WC–Fe–Cr–C PTA overlays in concentrated slurries , 2009 .

[2]  M. Roy,et al.  Wear behaviour of hardfaced Fe-Cr-C alloy and austenitic steel under 2-body and 3-body conditions at elevated temperature , 2010 .

[3]  M. Zivkovic,et al.  Theoretical-experimental determining of cooling time (t8/5) in hard facing of steels for forging dies , 2010 .

[4]  P. H. Shipway,et al.  Microstructure and abrasive wear behaviour of shielded metal arc welding hardfacings used in the sugarcane industry , 2007 .

[5]  L. Lim,et al.  Laser cladding of nickel-based hardfacing alloys , 1998 .

[6]  J. Coronado.  Effect of (Fe,Cr)7C3 carbide orientation on abrasion wear resistance and fracture toughness , 2011 .

[7]  J. Hawk,et al.  Solidification structure and abrasion resistance of high chromium white irons , 1997 .

[8]  Irina Hussainova,et al.  Mechanical properties and features of erosion of cermets , 2001 .

[9]  B. Mellor.  Surface Coatings for Protection against Wear , 2006 .

[10]  M. Roy,et al.  Erosive wear of hardfaced Fe-Cr-C alloys at elevated temperature , 2009 .

[11]  Xiangyang Xu,et al.  Microstructure and dry-sliding wear resistance of PTA clad (Cr, Fe)7C3/γ-Fe ceramal composite coating , 2006 .

[12]  J. Kuo,et al.  Effect of carbon content on solidification behaviors and morphological characteristics of the constituent phases in Cr-Fe-C alloys , 2011 .

[13]  I. Hussainova.  Effect of microstructure on the erosive wear of titanium carbide-based cermets , 2003 .

[14]  P. Shipway,et al.  A comparison of the abrasive wear behaviour of iron-chromium based hardfaced coatings deposited by SMAW and electric arc spraying , 2008 .

[15]  M. Ashby,et al.  Engineering Materials 2: An Introduction to Microstructures, Processing and Design , 1986 .

[16]  M. Antonov,et al.  Cermets surface transformation under erosive and abrasive wear , 2010 .

[17]  E. Badisch,et al.  Effect of carbide degradation in a Ni-based hardfacing under abrasive and combined impact/abrasive conditions , 2011 .

[18]  H. Sōda,et al.  Microstructure and mechanical properties of Fe–Cr–C eutectic composites , 2003 .

[19]  S. Buytoz.  Microstructural properties of M7C3 eutectic carbides in a Fe–Cr–C alloy , 2006 .

[20]  Weite Wu,et al.  Microstructural and abrasive characteristics of high carbon Fe–Cr–C hardfacing alloy , 2010 .

[21]  Friedrich Franek,et al.  Behaviour of iron-based hardfacing alloys under abrasion and impact , 2008 .

[22]  H. Sabet,et al.  The Microstructure and Abrasive Wear Resistance of Fe–Cr–C Hardfacing Alloys with the Composition of Hypoeutectic, Eutectic, and Hypereutectic at $$ \frac{Cr}{C} = 6 $$ , 2011 .