Research Of Technology And Cladding Path Of Plasma Cladding Fe-Ni Alloy Coating On The Surface Of High Manganese Steel

When high manganese steel is impacted or squeezed under the stress condition of high stress and high load,the surface layer will have obvious work hardening,which results in a large increase in hardness,while the internal toughness of high manganese steel remains unchanged.However,the work hardening of high manganese steel is not obvious under low stress conditions,so it is prone to wear failure.Fe-Ni alloy coating on the surface of high manganese steel can effectively improve the wear resistance and service life of high manganese steel.Mine equipment and associated vulnerable parts are usually large in size and irregular in shape.Plasma cladding requires multi-pass cladding to form a large-area wear-resistant coating.The accumulation of heat and the increase of the substrate temperature will occur during the long-time cladding process.The change of the temperature of the cladding substrate will affect the cooling condition of the wear-resistant coating,which in turn affects the microstructure and properties of the coating.It is one of the key technologies to obtain the plasma cladding technology applied to the surface strengthening and industrialization of high manganese steel to master the cladding trajectory of the metal-based wear-resistant coating on the surface of high manganese steel.However,there is a lack of experimental research and data support for large area metal-based wear-resistant coating on the surface of high manganese steel.In this paper,the Fe-Ni based cladding layer was prepared on the surface of high-manganese steel by plasma cladding technology.Based on the comprehensive exploration of the plasma cladding process parameters on the microstructure and properties of the cladding layer,the process and properties of multi-channel plasma cladding Fe-Ni alloy coating were studied.The effects of the lap ratio which is 20%,30%,40%,50%and different cladding paths on the macro morphology,micro-hardness,wear properties and corrosion resistance of the cladding layer were studied.The microstructure and phase composition of the cladding layer under better lap ratio and cladding path were analyzed.The experimental results show that under the condition of working current of 100A,scanning speed of 180mm/min and ion torch height of 6mm,the cladding layer has fine equiaxed structure at the top,columnar structure at the middle,and equiaxed crystal between the bottom columnar crystal and the substrate.There is an obvious bright line between the base and the substrate,which indicates that the matrix and the cladding layer have good metallurgical bonding.The phase of the cladding layer is mainly?-?Fe,Ni?solid solution phase,and intermetallic compounds such as Co₃Fe₇,Fe_10.8Ni and Fe_9.7Mo_0.3 are also formed.In the plasma cladding test with different working currents,when the working current is slowly increased,the width of the cladding layer increases sequentially,the height sequentially decreases,the depth of the molten pool sequentially increases,and the dilution rate gradually decreases.The average hardness of the cladding layer reduces,and the wear loss and the self-corrosion current of the cladding layer increases.When the working current is 100A and 120A,the surface morphology of the cladding layer is better,there are no obvious pores and cracks,the width,height and dilution rate of the cladding layer are suitable.When the working current is 60A,the average hardness,wear loss and self-corrosion current are 436.3 HV,4.7 mg and 9.51?A,which has the best overall performance.In the plasma cladding test with different scanning speeds,with the increase of scanning speed,the width of the cladding layer,the height of the cladding layer,the depth of the bath and the dilution rate decrease gradually;the average hardness of the cladding layer reduces.The change of wear loss of cladding layer is irregular and the self-corrosion current of the cladding layer reduces.The surface morphology of the cladding layer at different scanning speeds is good,without obvious pores and cracks.At scanning speeds of 180mm/min and240mm/min,the width,height and dilution rate of the cladding layer are suitable.The average hardness and wear loss of the cladding layer with scanning speed of 120mm/min are427.7HV and 5.4 mg,which has the highest hardness and the best wear resistance;the self-corrosion current of the cladding layer with scanning speed of 300 mm/min is 3.255?A,which has the best corrosion resistance.In plasma cladding test with different ion torch height,with the increase of ion torch height,the width of the cladding layer decreases first and then increases,the height of the cladding layer increases first and then decreases,the depth of the molten pool decreases,and the dilution rate decreases.When the ion torch height is 6mm and 7mm,the surface morphology of the cladding layer is better,there are no obvious pores and cracks,the width,height and dilution rate of the cladding layer are suitable.The average hardness and wear loss of the cladding layer with ion torch height of 7 mm are 433.7 HV and 5.2 mg,which has the highest hardness and best wear resistance;The self-corrosion current of the cladding layer with ion torch height of 8 mm is 1.917?A,which has the best corrosion resistance.In plasma tests with different lap ratio,the microstructure of the lap zone in the two cladding layers is complex,and there are fine equiaxed and dendrite structures.The phase of the cladding layer is mainly composed of?-?Fe,Ni?solid solution phase,followed by Co₃Fe₇?Fe_10.8Ni?Fe_9.7Mo_0.3and Ni₃Si.The average hardness of the cladding layer with lap ratio of 50%is 444.2 HV,which is the highest hardness.The wear loss and self-corrosion current of the cladding layer with lap ratio of 30%are 4.3 mg and 8.086?A,which has the best wear resistance and corrosion resistance.In the plasma test of different cladding paths,the phase in the large-area cladding layer is dominated by?-?Fe,Ni?solid solution phase,followed Co₃Fe₇?Fe_10.8Ni?Fe_9.7Mo_0.3?Ni₃Si and Mo₉Ti₄.The average hardness and wear loss of the cladding layer of path 3 is 452.7HV and 3.1mg,which has the highest hardness and the best wear resistance.The self-corrosion current of the cladding layer of path 1 is 2.49?A,which has the best corrosion resistance.