Hard-yet-tough high vanadium high speed steel composite coating in-situ alloyed on ductile iron by atmospheric plasma arc

Activity: Talk or presentationProfessional

Yutao Pei - Invited speaker

A graded high-vanadium alloy composite coating was synthesized from premixed powders (V, Cr, Ti, Mo, Nb) on ductile iron (DI) substrate via atmospheric plasma surface alloying process. The resulted cross-section microstructure is divided into three distinct zones: upper alloyed zone (AZ) rich with spherical primary carbides, middle melted zone (MZ) with fine white iron structure and lower heat affected zone (HAZ). Spherical or bulk-like primary carbides with diameter < 1 μm in the AZ are formed via in-situ reactions between alloy powders and graphites in DI. Microstructural characterizations indicate that the carbides are primarily MC-type (M=V, Ti, Nb) carbides combined with mixed hard-phases such as M2C, M7C3, M23C6, and martensite. Disperse distribution of spherical, submicro-sized metal carbides in an austenite /ledeburite matrix render the graded coating hard-yet-tough. The maximum microhardness of the upper alloyed zone is 950 HV0.2, which is 5 times that of the substrate. Significant plastic deformation with no cracking in the micro-indentations points to a high toughness. The graded high-vanadium alloy composite coating exhibits superior tribological performance in comparison to Mn13 steel and PTA-remelted DI.

Event (Conference)

Title8th International Conference on Computational Methods and Experiments in Material and Contact Characterisation, Materials Characterisation 2017

ID: 54826803