The pulsed magneto-oscillation （PMO） technique has the potential to be applied in the production of heavy steel ingot. In order to confirm it and achieve more insights, the solidification of rectangular 65Mn steel i...The pulsed magneto-oscillation （PMO） technique has the potential to be applied in the production of heavy steel ingot. In order to confirm it and achieve more insights, the solidification of rectangular 65Mn steel ingot with the size of 220 mm×220 mm × 1000 mm was investigated under the impact of PMO. Experimental results present that PMO treatment can remarkably refine the solidified microstructure of 65Mn steel ingot in comparison with the reference ingot without PMO. The application of PMO not only significantly reduces the grain size, but also promotes the morphology transition of equiaxed grains from well-developed dendritic structures to globular structures. And the resulted globular morphology is mainly due to the fact that the PMO-induced forced flow enhances the stability of crystal growth. As a consequence, the average tensile strength of as-cast samples is enhanced from 643.4 to 762.9 MPa under the application of PMO.展开更多
In the present work,the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel.The mechanical and wear behaviors of the laminar plasma surface h...In the present work,the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel.The mechanical and wear behaviors of the laminar plasma surface hardened 65 Mn steel were analyzed.The martensite transition transformation of the temperature of the laminar plasma-hardened 65 ferrite Mn steel was determined by a thermal-solid coupling model.Based on the orthogonal experimental results,the optimal hardening parameters were confirmed.The scanning velocity,quenching distance and arc current are 130 mm/min,50 mm and 120 A,respectively.The pearlites and ferrites are transformed into martensites in the hardened zone,while the ratio of martensite in the heataffected zone decreases with the increase in the hardening depth.Compared to the untreated 65Mn steel,the average hardness increases from 220 HV_(0.2)to 920 HV_(0.2)in the hardened zone and the corresponding absorbed power increases from 118.7 J to 175.5 J.At the same time,the average coefficient of friction(COF)decreases from 0.763 to 0.546,and the wear rate decreases from 5.39×10^(-6)mm^(3)/(N·m)to 2.95×10^(-6)mm^(3)/(N·m),indicating that the wear resistance of 65Mn steel could be significantly improved by using laminar surface hardening.With the same hardening parameters,the depth and width of the hardened zone predicted by the thermal-solid coupling model are 1.85 mm and 11.20 mm,respectively,which are in accordance with the experimental results;depth is 1.83 mm and width is 11.15 mm.In addition,the predicted hardness distributions of the simulation model are in accordance with the experimental results.These results indicate that the simulation model could effectively predict the microstructure characteristics of 65 Mn steel.展开更多
基金Acknowledgements The authors acknowledge the financial supports from the National Natural Science Foundation of China （Grant No. 51320105003）, Shanghai government （Grant No. 14DZ2261200）, and the Science and Technology Commission of Shanghai Municipality （Grant No. 15520710800）.
文摘The pulsed magneto-oscillation （PMO） technique has the potential to be applied in the production of heavy steel ingot. In order to confirm it and achieve more insights, the solidification of rectangular 65Mn steel ingot with the size of 220 mm×220 mm × 1000 mm was investigated under the impact of PMO. Experimental results present that PMO treatment can remarkably refine the solidified microstructure of 65Mn steel ingot in comparison with the reference ingot without PMO. The application of PMO not only significantly reduces the grain size, but also promotes the morphology transition of equiaxed grains from well-developed dendritic structures to globular structures. And the resulted globular morphology is mainly due to the fact that the PMO-induced forced flow enhances the stability of crystal growth. As a consequence, the average tensile strength of as-cast samples is enhanced from 643.4 to 762.9 MPa under the application of PMO.
基金appreciate the support of the Key Laboratory of Mechanical Structure Optimization&Material Application Technology of Luzhou(No.SCHYZSA-2022-02)the Scientific Research and Innovation Team Program of Sichuan University of Science and Technology(No.SUSE652A004)+1 种基金the Key Laboratory of Intelligent Manufacturing of Construction Machinery Project(No.IMCM202103)the Panzhihua Key Laboratory of Advanced Manufacturing Technology Open Fund Project(No.2022XJZD01)。
文摘In the present work,the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel.The mechanical and wear behaviors of the laminar plasma surface hardened 65 Mn steel were analyzed.The martensite transition transformation of the temperature of the laminar plasma-hardened 65 ferrite Mn steel was determined by a thermal-solid coupling model.Based on the orthogonal experimental results,the optimal hardening parameters were confirmed.The scanning velocity,quenching distance and arc current are 130 mm/min,50 mm and 120 A,respectively.The pearlites and ferrites are transformed into martensites in the hardened zone,while the ratio of martensite in the heataffected zone decreases with the increase in the hardening depth.Compared to the untreated 65Mn steel,the average hardness increases from 220 HV_(0.2)to 920 HV_(0.2)in the hardened zone and the corresponding absorbed power increases from 118.7 J to 175.5 J.At the same time,the average coefficient of friction(COF)decreases from 0.763 to 0.546,and the wear rate decreases from 5.39×10^(-6)mm^(3)/(N·m)to 2.95×10^(-6)mm^(3)/(N·m),indicating that the wear resistance of 65Mn steel could be significantly improved by using laminar surface hardening.With the same hardening parameters,the depth and width of the hardened zone predicted by the thermal-solid coupling model are 1.85 mm and 11.20 mm,respectively,which are in accordance with the experimental results;depth is 1.83 mm and width is 11.15 mm.In addition,the predicted hardness distributions of the simulation model are in accordance with the experimental results.These results indicate that the simulation model could effectively predict the microstructure characteristics of 65 Mn steel.
