Study On Microstructure And Properties Of Nodular Cast Iron Textured By Plasma Beam Arc

By 2020,China’s crude steel production ranks first in the world.The wear and fatigue failure of rollers,especially hot rollers,is inevitable due to the large crude steel rolling process.The repair and remanufacture of the hot rollers are imperative.The repair and remanufacturing method of the hot rollers will influence the service life of hot roller,the rolling quality of crude steel and the production cost of rolling enterprises.The application of plasma beam to roller cladding or alloying has many advantages,for example,simple operation,fast processing speed,simple processing equipment and so on.At present,plasma beam cladding or alloying treatment is widely used in the field of the rollers repair and remanufacturing,and the method of plasma beam repair of the rollers is favored by enterprises and researchers.In this paper,cobalt based high-speed steel(HSS)was used as the coating material for rollers repair.Based on commercial W2Mo9Cr4VCo8 cobalt based high speed steel alloy,an alloy coating suitable for hot roller repair was developed during the repair and remanufacture of the hot rollers using plasma beam.Cobalt based high speed steel coating was prepared by taking the cobalt content in W2Mo9Cr4VCo8 alloy coating as the unit of measurement,that is,the mass proportion of cobalt in alloy coating was 0%,9.55%,17.42% and 24%,respectively.Cobalt-based HSS alloy coating was prepared on QT600-3 nodular iron plate by plasma beam.1.The cobalt-based HSS alloy coating was prepared on QT600-3 ductile iron by plasma beam alloying.The non-equilibrium solidification carried out in the alloy coating,and the microstructure was mainly typical hypoeutectic white cast iron,which consisted of ledeburite microstructure composed of pearlite and eutectic cementite.With the increase of cobalt content in alloy coatings,the sizes and morphologies of eutectic cementite in alloy coatings changed,and the types of carbides and intermetallic compounds forming in alloy coatings changed.The four kinds of alloy coatings prepared by plasma beam had higher Vickers hardness and wear resistance at room temperature,the alloy coating with 0% cobalt content had excellent wear resistance at room temperature.2.In order to explore the high-temperature properties of the alloy coatings,the four kinds of alloy coatings were tempered at 640 ℃ for four times respectively,and the red hardness of the alloy coatings were determined.The results showed that the red hardness of the alloy coating was the highest when the cobalt content is 0%,and the red hardness stability of the alloy coating was better when the cobalt content is17.42%.Then,the alloy coatings with 0% and 17.42% cobalt content in the alloy coating were subjected to high temperature friction and wear at 700 ℃.The results showed that the alloy coatings with both kinds of alloy coatings had good high temperature wear resistance.Compared with the alloy coatings with 0% cobalt content,the alloy coating with 17.42% cobalt content has better wear resistance at high temperature.3.The point texture and linear texture was carried out by plasma beam using the alloy coating with 17.42% cobalt content.Then the two kinds of texture coatings were respectively subjected to high temperature friction and wear at 700 ℃,and the high temperature friction and wear properties of the two kinds of texture coatings were compared with that of the linear lap alloy coating.The results showed that the high temperature wear resistance of point texture alloy coating is better than that of linear texture alloy coating and linear lap alloy coating.Therefore the alloy coating with 17.42% cobalt content had better friction and wear properties at high temperature after point texturing,and the alloy coating was more suitable for point texturing repair of hot rollers by plasma beam.