Study On Multiple Composite Reinforced Wear-resistant Surfacing Flux Cored Wire And Wear-resistance Mechanism Of Surfacing Layer

Abrasive wear is one of the important factors that restrict the rapid development of industrial enterprises in China.The overall preparation of wear-resistant materials is not only costly,but also difficult for secondary processing.The wear-resistant layer made of surfacing with flux cored wire is not only able to improve its wear-resistance,but also be more economical and effective.Fe-Cr-C flux cored wire is an important wear-resistant surfacing material.Due to its high hardness,high wear-resistance and low price,it is widely used in the working conditions of low stress abrasive wear.In order to improve the performance of Fe-Cr-C alloy,B,Ti,W and N elements were added to the alloy system to achieve multiple composite reinforcement and preparation of Fe-Cr-C-B,Fe-Cr-C-B-Ti,Fe-Cr-C-B-W and Fe-Cr-C-B-N-Ti self-protective wear-resistant surfacing flux cored wire.The corresponding surfacing alloy was prepared on the surface of Q235 metal by the method of bright arc surfacing.Firstly,the influence of alloy elements on the property of the welding process was studied.The microstructure,phase composition and property of surfacing layer were analyzed,and the relationship among the microstructure,hardness and wear-resistance of surfacing layer was studied.The wear-resistance mechanism of surfacing layer was discussed.After research and analysis,the following conclusions are obtained.?1?In the studied alloy system,moderate C and B can stabilize welding arc,reduce welding spatter and pore,ensure good weld formation.However,excessive addition will increase the sensitivity of crack.Moderate Ti reduce welding dust,pore and spatter,and ensure good weld formation.The increase of W content can increase the tendency of welding fume,weld surface residue and crack.The increase of N content can deteriorate the stability of the welding arc,leads to the increase of pore and spatter.?2?For Fe-Cr-C-B surfacing alloy,the alloy system is a typical hypoeutectic alloy.When the content of C is 1.54%and the content of B?in the form of ferro-boron?is 0.81%,the M₃?C,B?with the fishbone and honeycomb distribution in surfacing layer is the least.The M₂₃?C,B?₆ with the chrysanthemum and lamellar distribution and the M₇?C,B?₃ with the block distribution are the most.As a wear-resistant framework,the M₂₃?C,B?₆ and M₇?C,B?₃ are well combined with the matrix structure.The wear-ability of surfacing layer is the best at this time.?3?For Fe-Cr-C-B-Ti surfacing alloy,Ti and B can change the phase composition of surfacing layer.When the content of Ti is 1.43%and the content of B is 0.84%,the hard phase particles of primary TiC,TiB₂ and Ti?C,B?_m are the most,and distribute uniformly.With the support of matrix structure,the framework of eutectic hard phase can effectively block the grinding of abrasive,and improve the wear-resistance of surfacing layer.?4?In the Fe-Cr-C-B-W surfacing alloy,there are no typical primary WC hard phase particle formation.In addition to partial solution in primary austenite and eutectic austenite,most of W are migrated to the grain boundary to generate Fe₃W₃C with better stability than WC.With the increase of W and B,the number of eutectic hard phases M₇?C,B?₃,M₃?C,B?and Fe₃W₃C also increase,and the spacing decrease and uniformly distribute with a continuous network.When the content of W is 3.47%and the content of B is 0.55%,the wear-resistance of surfacing layer is the best.?5?For Fe-Cr-C-B-N-Ti surfacing alloy,when Ti is not added,the surfacing layer has the best wear-resistance when the content of N is 0.17%.At this time,granular BN is formed on the primary austenite grain of surfacing layer,and the hard phase M₂₃?C,B?₆,M₃?C,B?and M₂B are uniformly distributed,and the number is the most.With the addition of Ti,primary hard phase particles TiB₂,TiN and TiC are formed in surfacing alloy.At the same time,with the increase of TiB₂,TiN,and TiC,BN gradually decreases and eventually disappears.When the content of Ti is 1.03%,the surfacing layer obtains the best wear-resistance.?6?The four types of surfacing alloys have metallurgical bonding with the base metal,and the surfaces are well formed.The comparison shows that the Fe-Cr-C-B-N-Ti surfacing alloy has the best wear-resistance.The wear-resistance mechanism is the coexistence of multiple plastic deformations and brittle fractures.Compared with the Fe-Cr-C-B alloy surfacing alloy which with the best performance,its hardness increased by 4.5HRC and its wear extent decreased by 0.3200g.According to the characteristics of wear process of Fe-Cr-C-B-N-Ti surfacing alloy,a low-stress abrasive wear model is established,and the model can qualitatively analyze the wear-resistance of surfacing alloy.