To investigate the effect of Mo element on the microstructure and properties of the high chromium cast iron flux-cored wire hardfacing layer, the work aims to conduct a series of experimental researches and analyses. In the experimental method, Cr27 high chromium cast iron hardfacing specimens with and without Mo element were prepared respectively under the cold metal transfer (CMT) arc hardfacing process. To systematically explore the effect of Mo addition on the hardfacing layer, multiple characterization and testing methods were employed. Penetrant testing (PT) was used to detect the macroscopic defects of the hardfacing layer, scanning electron microscopy (SEM) was applied to observe the macro morphology and microstructure of the hardfacing layer, electron backscatter diffraction (EBSD) was adopted to analyze the grain size and distribution of the microstructure and the pin-on-disk wear test was carried out to evaluate the wear resistance of the hardfacing layer. Through the combination of these methods, the effect law of Mo element on the macro morphology, microstructure and wear resistance of the hardfacing layer was comprehensively studied. The experimental results showed that the addition of Mo element had obvious effects on the hardfacing process and the performance of the hardfacing layer. During the hardfacing process, the addition of Mo significantly increased the spatter and induced the formation of transverse cracks in the hardfacing layer. Microstructurally, both the Mo-containing and Mo-free hardfacing layers were mainly composed of (Fe, Cr)7C3 eutectic carbides and an austenite matrix. However, the addition of Mo brought significant microstructural changes: it notably refined the austenite grains of the hardfacing layer and increased the volume fraction of M7C3 carbides. Specifically, compared with the Mo-free hardfacing layer, the austenite grain size of the Mo-added hardfacing layer was refined by approximately 38.6%. In terms of mechanical properties, the average hardness of the Mo-added hardfacing layer increased from 690HV (of the Mo-free one) to 740HV, with an improvement of about 7%. In the wear resistance test, the average friction coefficient of the Mo-added hardfacing layer decreased from 0.645 (of the Mo-free one) to 0.395, and the wear mass loss was reduced by approximately 50%, indicating a significant improvement in wear resistance. The conclusion of this work is as follows: during the solidification process of the hardfacing layer, Mo element first precipitates Mo2C with a high melting point. This Mo2C acts as a heterogeneous nucleation core, which effectively increases the nucleation rate of austenite. In the later stage of solidification, Mo2C can also pin the grain boundaries, inhibiting the growth of austenite grains, thereby achieving the refinement of austenite grains. In addition, the addition of Mo element can reduce the solid solubility of C element in austenite, which promotes more C element to participate in the eutectic reaction, ultimately increasing the content of M7C3 carbides. The increase in carbide content and the refinement of grains together contribute to the improvement of the hardfacing layer's hardness. Regarding the wear mechanism, both the Mo-containing and Mo-free hardfacing layers are mainly dominated by adhesive wear and abrasive wear. However, the addition of Mo element significantly reduces the friction coefficient and wear mass loss of the hardfacing layer, thereby effectively enhancing its wear resistance.
Key words
Mo element /
high chromium cast iron /
grain refinement /
M7C3 carbide /
wear /
CMT hardfacing
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] WU S Y, WANG D C, TAO X P, et al.Normalizing Temperature Influence on the Microstructure Characteristics, Mechanical and Wear Performance of a Novel High Chromium Cast Iron[J]. Tribology International, 2025, 202: 110327.
[2] BOCHENEK K, DLOUHY I, WĘGLEWSKI W, et al. Fracture and Wear Behavior of High-Chromium Cast Iron Obtained from Industrial Waste and Reinforced with Alumina Particles[J]. Journal of Materials Research and Technology, 2025, 37: 1579-1595.
[3] SHI R K, XU X C, LIU Y Q.Structure Characterization and Failure Mechanisms of High Chromium Cast Iron Grate Bar[J]. Engineering Failure Analysis, 2024, 156: 107849.
[4] KALANTARIAN R, KIAYEE N, FARZADI A, et al.Erosion Behavior of Various High Chromium Cast Iron Alloys Exposed to Gas-Blast Stream of Ferric Oxide Particles[J]. Engineering Failure Analysis, 2024, 163: 108520.
[5] GONG L Q, FU H G, YANG P H, et al.Refinement of Primary Carbides and Improvement of Wear Resistance of Hypereutectic High Chromium Cast Iron after Modification[J]. Journal of Materials Research and Technology, 2023, 24: 5724-5742.
[6] WANG C J, HUANG F, HE L, et al.Research and Verification of Cracking Failure Mechanism of High Chromium Cast Iron Impeller Blade under Eco Pickled Surface Conditions[J]. Engineering Failure Analysis, 2025, 182: 110018.
[7] SHAO W, ZHOU Y F, ZHOU L, et al.Effect of Ti- Doping on Peeling Resistance of Primary M7C3 Carbides in Hypereutectic Fe-Cr-C Hardfacing Coating and γ-Fe/ M7C3 Interfacial Bonding Strength[J]. Materials & Design, 2021, 211: 110133.
[8] CHANG C M, CHEN L H, LIN C M, et al.Microstructure and Wear Characteristics of Hypereutectic Fe-Cr-C Cladding with Various Carbon Contents[J]. Surface and Coatings Technology, 2010, 205(2): 245-250.
[9] FAN C, CHEN M C, CHANG C M, et al.Microstructure Change Caused by (Cr, Fe)23C6 Carbides in High Chromium Fe-Cr-C Hardfacing Alloys[J]. Surface and Coatings Technology, 2006, 201(3/4): 908-912.
[10] ADACHI Y, HAKATA K, TSUZAKI K.Crystallographic Analysis of Grain Boundary BCC-Precipitates in a Ni-Cr Alloy by FESEM/EBSD and TEM/Kikuchi Line Methods[J]. Materials Science and Engineering: A, 2005, 412(1/2): 252-263.
[11] NEVILLE A, REZA F, CHIOVELLI S, et al.Characterization and Corrosion Behavior of High-Chromium White Cast Irons[J]. Metallurgical and Materials Transactions A, 2006, 37(8): 2339-2347.
[12] WANG X H, HAN F, LIU X M, et al.Microstructure and Wear Properties of the Fe-Ti-V-Mo-C Hardfacing Alloy[J]. Wear, 2008, 265(5/6): 583-589.
[13] MATSUBARA Y, SASAGURI N, SHIMIZU K, et al.Solidification and Abrasion Wear of White Cast Irons Alloyed with 20% Carbide Forming Elements[J]. Wear, 2001, 250: 502-510.
[14] WANG X H, HAN F, QU S Y, et al.Microstructure of the Fe-Based Hardfacing Layers Reinforced by TiC-VC- Mo2C Particles[J]. Surface and Coatings Technology, 2008, 202(8): 1502-1509.
[15] WANG X H, HAN F, LIU X M, et al.Effect of Molybdenum on the Microstructure and Wear Resistance of Fe-Based Hardfacing Coatings[J]. Materials Science and Engineering: A, 2008, 489(1/2): 193-200.
[16] SCANDIAN C, BOHER C, DE MELLO J D B, et al. Effect of Molybdenum and Chromium Contents in Sliding Wear of High-Chromium White Cast Iron: The Relationship between Microstructure and Wear[J]. Wear, 2009, 267(1/2/3/4): 401-408.
[17] IMURAI S, THANACHAYANONT C, PEARCE J T H, et al. Effects of Mo on Microstructure of As-Cast 28wt.%Cr-2.6wt.%C-(0-10)wt.% Mo Irons[J]. Materials Characterization, 2014, 90: 99-112.
[18] FILIPOVIC M, KAMBEROVIC Z, KORAC M, et al.Microstructure and Mechanical Properties of Fe-Cr-C-Nb White Cast Irons[J]. Materials & Design, 2013, 47: 41-48.
[19] BOUHAMLA K, HADJI A, MAOUCHE H, et al.Effect of Manganese and Molybdenum on the Microstructure, the Shape of Secondary Precipitation, and the Wear Behavior of a High Chromium Cast Iron[J]. International Journal of Metalcasting, 2024, 18(2): 1062-1074.
[20] RUANGCHAI K, TONGSRI R, PEARCE J T H, et al. Erosion-Corrosion Behavior of As-Cast and Destabilized High Chromium Cast Irons with Mo and W Addition[J]. Metallurgical and Materials Transactions A, 2024, 55(8): 2644-2660.
[21] JILLEH A, KISHORE BABU N, THOTA V, et al.Microstructural and Wear Investigation of High Chromium White Cast Iron Hardfacing Alloys Deposited on Carbon Steel[J]. Journal of Alloys and Compounds, 2021, 857: 157472.
[22] 钟世杰, 魏昕, 龚郡, 等. 中厚板低碳钢激光深熔焊接气孔形成特征研究[J]. 应用激光, 2021, 41(4): 697-703.
ZHONG S J, WEI X, GONG J, et al.Research on Porosity Formation of Medium Thick Plate of Mild Steel in Laser Deep Penetration Welding[J]. Applied Laser, 2021, 41(4): 697-703.
[23] 吕仁杰, 裴伟. 高锰钢研究进展和展望[J]. 冶金设备, 2019(4): 57-61.
LYU R J, PEI W.Research Progress and Prospect of High Manganese Steel[J]. Metallurgical Equipment, 2019(4): 57-61.
[24] JILLEH A, BABU N K, THOTA V, et al.Microstructural and Mechanical Properties Investigation of TiC Reinforced Hardface Alloy Deposited on Mild Steel Substrate[J]. Transactions of the Indian Institute of Metals, 2013, 66(4): 433-436.
[25] 皮自强, 杜开平, 郑兆然, 等. 钼含量对铁基激光熔覆层组织和性能的影响[J]. 热喷涂技术, 2021, 13(1): 85-90.
PI Z Q, DU K P, ZHENG Z R, et al.Effect of Mo Content on the Structure and Properties of Fe-Based Laser Cladding Layers[J]. Thermal Spray Technology, 2021, 13(1): 85-90.
[26] KLEYKAMP H.Thermodynamic Studies on Chromium Carbides by the Electromotive Force (EMF) Method[J]. Journal of Alloys and Compounds, 2001, 321(1): 138-145.
Funding
Science and Technology Project of Guangdong Administration for the Market Regulation (2025CT12)
PDF(12192 KB)
