‎محمد حسن عباسي

10/8/91

كيوان رئيسي، مرتضي شمعانيان

1396/09/20

كتابنامه

مواد

مهندسي مواد

ID6709

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Production and Evaluation of Nickel Free High Nitrogen Stainless Steel from Powder Fabricated by Mechanical Alloying Rezvan Sharifirenani Email address r sharifirenani@ma iut ac ir Date of Submission April 22 2012 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi edris@cc iut ac ir Mohammad Ali Golozar Professor golozar@cc iut ac ir Abstract During the last years nano structure Ni free high nitrogen stainless steels HNSS have been extensively investigated due to their excellent properties Presence of nitrogen in nano structural materials have led to excellent mechanical properties and high corrosion resistance Replacement of nickel with nitrogen could eliminate the allergetic effect and make the material suitable as implants in human body So far manufacturing these steel have been carried out using different melting methods Due to limited solubility of nitrogen in liquid phase researchers have concentrated on solid state methods like powder metallurgy The aim of this research work was to synthesis and characterize the properties of nano structureed Ni free high nitrogen stainless steels of Fe Cr Mn Mo and Fe Cr Mn by mechanical alloying under nitrogen atmosphere In this way nano structured solid solution HNSS powders Fe 18Cr 8Mn 4Mo Fe 18Cr 8Mn 8Mo Fe 18Cr 8Mn and Fe 18Cr 9Mn were synthesized and then Fe Cr Mn Mo and Fe Cr Mn powders were cold pressed The cold pressed samples were sintered at 1250 C for 60 minutes and then cooled in a mixture of ice and water Morphological and structural changes were examined using Scanning Electron Microscopy SEM Chemichal composition of products were determined using Elemental Analysis System EDS attached to SEM Nitrogen content was measured using Leco nitrogen analyser X Ray Difraction XRD was used to determine the phases produced Hardness and elastic modulus of sintered samples were measured using microhardness and nanoindentation tester Mechanical alloying results showed that nitrogen solubility in powders Fe 18Cr 8Mn 4Mo Fe 18Cr 8Mn 8Mo Fe 18Cr 8Mn and Fe 18Cr 9Mn significantly increases by increasesing the milling time as 0 76 1 1 0 9 and 0 8 wt respectively Microhardness of powders increased by increasesing the nitrogen solubility Hardness of bulks was evaluated as 422 604 517 and 434 HV respectively Also elastic modulus of four solid solution was determined as 272 390 344 and 326 GPa respectively Density and grain size measurement after cold pressing and sintering showed that the method used to produce HNSS bulk is successful Wear properties of samples wear rate friction coffecient and wear mechanism were studied using pin on disk machine applying 800 g load Wear test results showed that wear resistance is increased and friction coefficient is decresed due to presence of nitrogen in steel The dominant wear mechanism was also determined to be adhesive Also cold pressed and sintered samples were characterized by Tafel polarization Results showed that the current density of Fe 18Cr 8Mn 4Mo sample is lower than other ones Key Words High nitrogen stainless steel Nano structure Mechanical alloying Phase transformation Wear Nanoindentation Corrosion PDF created with pdfFactory trial version www pdffactory com

حسين ادريس، محمدعلي گلعذار

‎محمد حسن عباسي

كيوان رئيسي، مرتضي شمعانيان