Research On Overlaying Materials For Wear And Pattern Layer Of Extrusion Roller

Roller presser which developed in1980s is a new energy-saving cement grinding equipment of high efficiency and wide application. Extrusion roller is a very important parts,the surfacing quality mostly determine the service life of calender press. The roller surface is comprised of four layers:bond coat,transition layer, wear layer and pattern layer. Study of roller surfacing material and welding technology have important application significance.The paper describes multigroup surfacing alloys welded on Q235.In this thesis, the author researched in effects of Cr and Mo content on properties of wear layer overlaying alloys, effects of V and C content on properties of pattern layer overlaying alloys and effects of surfacing layers’numbers and types of heating and cooling on properties of overlaying alloys by OM,SEM,EDS,XRD,microhardness tester,rockwell hardness tester,wet sand rubber-type abrasion testing machine.The results show as follows:(l)The content of high carbon ferro-chrome has no impact on welding spatter,fume and slag detachability;when the content is75%(wt%),it generates a large amount of carbides and the highest hardness of HRC55.0;The wear resistant property is the best when the content of high carbon ferro-chrome is60%.(2)The content of Fe-Mo has no impact on welding spatter,fume,slag detachability.The hardness and wear resistant property increase with the increasing of Fe-Mo;The wear resistant property is the best when the content of Fe-Mo is20%.(3)The Fe-V has a significant influence on cracks.there are cracks in the welding without Fe-V,then with the increase of the addition of Fe-V into coat,it can reduce the crack number.When the content of Fe-V increases to22%,there is no crack in the surfacing layer;The highest hardness is HRC61.0when the Fe-V is20%and the lowest hardness is HRC21.6when the Fe-V is30%; The wear resistant property is the best when the content of Fe-V is20%-22%.(4)The slag detachability becomes bad and the fumes increase with the increasing of graphite,it produces lots of fumes when the graphite is24%; The morphological types of VC increase with the increasing of graphite, chrysanthemum distribution VC is not produced when the graphite is2%-12%while it produces when the graphite is16%-20%,there are lots of chrysanthemum distribution VC when the graphite is20%;The highest hardness is HRC67.1when the graphite is20%and the lowest hardness is HRC25.2without graphite; The wear resistant property is good when the content of graphite is12%-20%.(5)It formes a large number of dendritic crystallization with single layer surfacing and the number of dendritic crystallization decreases dramaticlly with double layer;The pattern of microstructure is not different and the content of carbides is very small difference between single and double layer;With double layer and different heating and cooling,the microstructure and hardness of three sample have small difference.