Study On Corrosion And Wear Of Sleeves And Bushings In High Temperature Liquid Zinc In Hot-dip Galvanizing Line

Low on-line life cycle of sink roll system in hot-dip galvanizing line can lead to frequent replacement of the roll system and seriously restrict the production efficiency of hot-dip galvanizing line,the rapid wear-corrosion failure between sleeves and bushings in the sink roll system was the key factor leading to short on-line cycle.Therefore,it is necessary to study the wear failure of sleeves and bushings of the sink roll system.Firstly,stress analysis of the rolls in sink roll system was carried out.The resultant force acting on the sink roll was the highest under tension of 20kN.The resultant force acting on the three rolls would increase with the increase of correction roll insertionΔx.The resultant force on stabilizing roll and correction roll increased obviously,while the resultant force on the sink roll increased less.The analysis about the contact stress between sleeves and bushings indicated that the contact stress at the center of the contact surface was highest,the contact stress was linearly distributed along the axial direction.When the sleeves were severely worn,the contact stress between sleeves and bushings was significantly increased.Metallurgical analysis of sleeves and bushings indicated that the material of sleeve was the stainless steel Fe-Cr-Ni and the material of bushing was co-based alloy.The corrosion mechanism of sleeves and bushings was the zinc atoms in liquid zinc diffused into the matrix through the surface of the matrix,the zinc-iron metallurgical combination to form zinc-iron compounds.Different phase layers were formed on the surface of the metal matrix due to the concentration difference when the zinc atoms diffused.The presence of loose porous channels in the corrosion product,the liquid zinc penetrated into the interior of the matrix through the channels and further corroded the matrix to form a corrosion layer.The Laves phase in the bushings has good corrosion resistance,and the cobalt-rich solid solution has poor corrosion resistance,so the liquid zinc preferentially corrodes the latter.The analysis of the microstructure and properties of the alloy layer of the corrosion product indicated that the microstructure of the alloy layer on the matrix surface wasγphase,δ₁ phase,ξphase andηphase from the matrix to the outside,and the properties of different phase layers were different.The wear mechanism of sleeves and bushings were mainly adhesive wear,abrasive wear,plastic deformation of local pits and peeling of surface materials.The surface of the material produced"furrows"under the abrasive wear.According to the results of corrosion experiments and wear experiments,it was considered that the corrosion products produced by zinc corrosion,which became abrasive particles under the function of wear and exacerbated the wear between sleeves and bushings.Based on the analysis of the composition,shape,hardness and wear test results of zincilate,the presence of zincilate particle aggravated the wear of sleeves and bushings and then caused their rapid failure.The comprehensive research results indicated that the dual function of liquid zinc corrosion and wear lead to the rapid failure of sleeves and bushings.