14143

12814

كارشناسي ارشد

استخراج فلزات

اصفهان : دانشگاه صنعتي اصفهان

1397

دوازده، ۷۸ص.: مصور، جدول، نمودار

حسين ادريس، علي شفيعي

مهدي احمديان، علي مالكي

1397/09/18

كتابنامه

مواد

مهندسي مواد

ID12814

78 Isfahan University of Technology Department of Materials Engineering Evolution of niobium content on the grain growth of DIN 1 7016 cementated steel Hamid habibollahi h habibollahi@ma iut ac ir june 12 2018Degree M Sc Language PersianSupervisor Ali Shafyei shafyei@cc iut ac ir Hosein Edris h edris@cc iut ac irAbstractIn this research the effect of Niobium microalloying element on microstructural evolutions andmechanical properties of DIN 1 7016 cementite steel in different conditions has been investigated Cementite steels containing different amounts of Nb microalloying element 0 02 0 06 and 0 09wt were alloyed and forged to improve the casting structure Prepared samples were dividedinto two groups Microstructural study and mechanical investigations were performed on a groupand the second group was carburized using the solid state cementation process at 940 C for 7hours finally were quenched in oil Results from microscopic study from the center of Samplesshowed that increasing Nb content up to 0 06 wt decreased the average grain size to 4 7 m 68 more than Nb free sample while further grain refinement was not detected in the steelcontaining 0 09 wt Nb with an average grain size of 6 m Grain size of second groupdecreased to 1 8 m with increasing niobium up to 0 6 from 4 8 m but in the amount of 0 09wt Nb the grain size was increased again Microstructural investigations of carbonated samplesusing scanning electron microscopy showed that the grain size variation from the internal to thesurface of the samples has increased Also with increasing niobium up to 0 09 wt the grain sizein the carbonaceous area reduced which can be due to the high carbon in carbonaceous area Tensile test confirmed the effect of NbC precipitation on the improvement of mechanicalproperties The results showed a promising strength elongation balance in terms of toughness for0 06 niobium without heat treatment steels 180 MPa compared to Nb free samples Also thehardness test results in both groups showed hardness increased up to 0 06 wt niobium whilethe niobium increases to 0 09 wt the hardness decreases again The highest tensile strength ofthe steel containing 0 06 wt niobium for the first and second groups equal to 776 MPa and 948MPa respectively Keywords DIN 1 7016 Cementite Steel Niobium Cementation Process

حسين ادريس، علي شفيعي

مهدي احمديان، علي مالكي