The Development And Research Of Air Queching Carbon Alloy Steel In Welding Wear-Resistant Sieve Plate

The Sieve plate in coke screening aera required higher wear-resistance and acertain tenacity, In order to meet this requirement, a welding structure is used, In thescreening process the Sieve which Directly contact with the coke are made by castingmaterials,and welded on carbon steel frame after heat treatment. Thus theperformance and tissue of casting article sieve has an important influence on thewear-resistance and fracture–resistance. Manufacturers currently use35CrMnSilow-alloy steel as the screening material,its heat treatment craft is water quenchingwith low temperature tempering.after heat treatment the tissue is Martensite,whichcan Guarantee sieve’s hardness and wear-resistance.but the article sieve is easy todeformation and cracking after haet treatment because of thin thickness, Seriouslyaffect the normal production and use of performance.In order to solve this problem,this paper intend to design a new material,the heat treatment is air-quenching toinstead of water-quenching,which can Solve the deformation and cracking afterArticle sieve cooled and Guarantee the performance of Sieve plate afer welding.hardness, weldability and heat treatment craft must be considered by choosingArticle sieve’s material,. The content of carbon and alloy elements have major impacton these properties.Six group of casting materials with different chemicalcomposition are designed for the experiment. These casting materials are treated bydifferent heat treatment,and go on wear test and welding test after heat treatment.Observe the microstructure tissue in cast and heat treatment condition, Measure thehardness and tenacity after different heat treatment,and test the fatigue life of weldedjoints.By experiments show, six group of as-cast samples’ tissue are pearlite、bainiteand intergranular chromium-rich tissue,as the increase of carbon content and alloyelements content, the segregation is getting worse. Austenitizing temperature has asignificant affect on tissue and performance of samples,the alloy-carbide declines,the hardness and toughness continuously improve as the Austenitizing temperaturheighte,which is sured to be M7C3by XRD,. But the austenitizing temperature is too high to lead the mechanical properties of the sample getting worse. Temperingtemperature has little effect on the martensite,which remians tempered martensite.Carbon and chromium content has great influence on the number andmorphology of martensite,the number of martensite increase as the enhance ofchromium content;the hardness of martensite increase as the Carbon content enhance,Low stress wear test for different samples after heat treatment show that,the wear-resistance improve as the increace of hardness.the wear style is micro-cuttingmechanism and a series of plastic deformation wear mechanism. The rate of abrasivewear accelerates In acidic environment,but this affect in alkaline environment is notSerious.Different part of sample experienced different welding thermal cycle afterwelding, its organization and performance will appear to varying changes. Base metalin the root of sieve plate is mainly martensite,which easy lead to welding crack,thecrack-rate is increase and the fatigue life is decrease as the rise of carbon andchromium content. The effect of welding thermal cycle for the face of sieve plate islittle,the decrease of handness is not serious.By comparing the mechanical properties of different sample after heat treatmentand fatigue life of welded joint, The comprehensive performance of5#sample isbest,the carbon content is0.42%, chromium content is4.82%,the The service life ofsieve plate made by this material is higher than6month though on-site test,whichimprove The production efficiency.