The effects of alloying elements over wear resistance in stainless steel material produced with powder metallurgy technique

ABSTRACTPhD ThesisTHE EFFECTS OF ALLOYING ELEMENTS OVER WEAR RESISTANCE IN STAINLESSSTEEL MATERIAL PRODUCED WITH POWDER METALLURGY TECHNIQUEVAHDETT N KOÇFırat UniversityGraduate School of Natural and Applied SciencesDepartment of Metallurgy Education2006, Page:139In this study, molybden, titanium, cobalt and boron elements were added to a austeniticstainless steel powder at the percentage of 1, 2 and 3 % and a composite material was produced by useof powder metallurgy techniques. The powder was pressed with 18 tons pressure and sintered at 1150°C temperature. Micro-structural and mechanical properties, abrasive and adhesive behaviours of theproduced composite material were investigated and tried to correlate between alloying elements andtheir percentage.The chanpes of the type and percentapes of alloying elements of composite material whichwere produced by powder metallurgy techniques resutted in the chanpes of the microstructures of thecomposites. When the matrix was examined, grain refinement, disintegration of grains, coarsening ofgrain boundaries, core forming etc. have been observed. It was also observed that the microstructuremainly consisted of γ-Fe, M23C6 and M7C3 phases.The investigations revealed that the alloying elements affected the hardness, microhardnessand toughness of composite austenitic stainless steel in proportion to to their percentage. When allsamples were examined, it was determined that the reinforcing elements (Mo, Ti, B and Co)positively affected the mechanical properties of austenitic stainless steel. The lowest surface hardnessand microhardness values were observed in unreinforced stainless steel samples. While the bestmechanical and wear properties were reached in the samples reinforced with boron, the samplesreinforced with Ti, Mo, and Co have not shown as good mechanical and wear properties as thespeciment reinforced with boron.In this study, it was show that it is possible to chance the hardness, microhardness, toughness,abrasive and adhesive wear resistance of austenitic stainless steel by adding Mo, Ti, B and Co. It wasalso pound that the formation of carbide, boride or any other compound and the disribution of thealloying additions in the matrix are the main factors determining the mechanical properties of thecomposite material.Key words: Powder metal, Austenitic stainless steel, Microstructure, Carbides, Adhesive wearing,Abrasive wearing, Toughness.