The Wear Behaviors of Various Si and Mn Contents on Fe-Cr-C Hardfacing Alloys

• Main Authors: Chi-Ming Lin, 林啟明
• Other Authors: 吳威德
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/63168966013927527766

碩士 === 國立中興大學 === 材料工程學系所 === 95 === This research discussed the wear behaviors of various Si and Mn contents on Fe-Cr-C hardfacing alloys. A series of Fe-Cr-C-xSi-yMn alloy fillers (x＝0.5~1.5wt％, y＝0.3~2.0 wt％) were designed to investigate the effect of Si and Mn on the wear behaviors of Fe-Cr-C hardfacing alloys. Gas tungsten arc welding (GTAW) was used to deposit these coating alloys on the S45C carbon steel substrates. The x-ray diffraction (XRD) and metallographic examination were carried out to understand the microstructure of these coating layers. Sand wheel abrasion test and adhesive wear test of ring-on-disc were used to evaluate the wear resistance of hardfacing alloys. In addition, the worn surfaces were observed with scanning electron microscope (SEM). The x-ray diffraction and metallurgy microstructure observation results revealed that the microstructure of coating layer consisted of massive amounts of martensite and a slight amounts of austenite. However, the content of martensite decreased with increasing of Mn contents in the coating layer. It was found form the EDS-mapping that the elements distributed uniformly without aggregation of the elements. The hardness test results showed that the hardness enhanced when the Mn contents decreased due to the amounts of martensite arose. But the hardness has no obvious variation with the addition of Si. Therefore, the highest hardness of coating layer was obtained in Fe-5.3Cr-0.6C-0.3Mn-0.5Si. The sand wheel abrasion test results indicated that the wear resistance of specimen increased with the martensite levels and the hardness value increasing in coating layer. The weight loss of coating layer increased with the addition of Mn contents, but the weight loss had unapparent change with the addition of Si. Hence, the best wear resistance of sand wheel abrasion was obtained in Fe-5.3Cr-0.6C-0.3Mn-1.0Si. The wear mechanism of sand wheel abrasion was affected with martensite levels and the hardness value of coating layer. When the hardness value exceeded HRC60 and the martensite levels of coating layer reached over 77%, the wear mechanism was controlled by microcutting, therefore the wear resistance of specimen became better. When the hardness value was below HRC56 and the martensite levels of coating layer was below 65%, the wear mechanism was controlled by the ploughing, therefore the wear resistance of specimen became worse. The adhesive wear test results represented that the wear rate decreased with increasing of the Mn contents because the martensite levels of coating layer decreased, but the wear rate had unapparent change with the addition of Si. For this reason, the best wear resistance of adhesive wear was obtained in Fe-5.3Cr-0.6C-1.4Mn-1.0Si. The wear mechanism of adhesive wear was affected with austenite levels of welding layer as well as the toughness of specimen surface. When the amount of austenite was 20~25%, the wear mechanism was controlled by the abrasive wear, therefore the wear resistance of specimen became worse. When the amount of austenite was 34%, the wear mechanism was controlled by the oxidative wear, therefore the wear resistance of specimen became better.