| LIU Tong,SUN Gui-fang,ZHANG Yong-kang.Microstructure and Wear Resistance of NiCr-Al2O3 Coating Alloyed with 45# Steel Laser[J],45(10):64-69 |
| Microstructure and Wear Resistance of NiCr-Al2O3 Coating Alloyed with 45# Steel Laser |
| Received:March 26, 2016 Revised:October 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.10.010 |
| KeyWord:laser alloying 45# steel Al2O3 microstructure microhardness wear resistance |
| Author | Institution |
| LIU Tong |
Southeast University, Nanjing , China |
| SUN Gui-fang |
Southeast University, Nanjing , China |
| ZHANG Yong-kang |
Southeast University, Nanjing , China |
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| Abstract: |
| The work aims to improve wear resistance of the flat die in flat-die pelletizer. The alloyed layer of NiCr-Al2O3 mixed in different ratios was fabricated on 45# steel by laser alloying technology. Phase composition and microstructure of the alloyed layer were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). Hardness change law of the alloyed layer was measured by FM-700 automatic micro-hardness tester. The wear resistance was investigated by screen display type abrasion tester. The experimental results indicated that the alloyed layer was mainly composed of martensite. Different fractions of undissolved Al2O3 particles were distributed dispersively in the alloyed layer. The heat-affected zone consisted of martensite and retained austenite. Primary phases of the alloyed layer were austenite and martensite. As the content of Al2O3 particles increased, the phase of martensite increased and the phase of austenite decreased. Thickness of the alloyed layer was approximately 0.9 mm. Surface micro-hardness value of the alloyed layer was nearly 2.4 times of that of the substrate and surface wear resistance was more than 6 times of that of the substrate. To some extent, the higher the content of Al2O3 particles in alloyed layer was, the greater the average micro-hardness of the alloyed layer and the better the wear resistance would be. The micro-hardness varied uniformly in the heat-affected zone, which provided a transition zone between the alloyed layer and the substrate. Wear mechanism was mainly plough wear, the existence of Al2O3 particles might reduce ploughing of abrasive particles on the substrate. The hardness and the wear resistance can be effectively improved by laser alloying Al2O3-NiCr mixed coating on 45# steel. Uniform alloyed surface with high hardness and wear resistance can be fabricated by laser alloying with NiCr + 30% Al2O3 particles. |
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