پديد آورنده :
منصورزاده، شيوا
عنوان :
تاثير نيتراسيون پلاسمايي بر مشخصات لايه سخت شده و رفتار تريبولوژيكي فولادهاي كم آلياژ كروم - موليبدن متالوژي پودر
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد
صفحه شمار :
[الف]، هشت، 153، [II]ص.: مصور، جدول، شكل، نمودار
يادداشت :
ص. ع. به فارسي و انگليسي
استاد راهنما :
فخرالدين اشرفي زاده
توصيفگر ها :
آلياژسازي , تف جوشي سختي , پودر آستالوي , همگن شدن منگنز , تريبولوژي , چگالي سنج-استاندارد , پراش پرتوايكس , سطح پين , شيارسايش
استاد داور :
كمال جانقربان، محمدعلي گلعذار، مهدي صالحي، غلامرضا آريانپور
تاريخ ورود اطلاعات :
1395/12/10
كد ايرانداك :
ID135 دكتري
چكيده فارسي :
به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي
چكيده انگليسي :
AbstractThe influence of plasma nitriding on microstructure hardness impact energy andtribological behaviour of two low alloy sintered steels was investigated A prealloyedFe Cr Mo powder was selected for nitriding and manganesewas added to one group of thesamplesto study its probable effect on the properties of the nitrided alloys Then compaction and sintering were performed on powder mixture in industrial scale Plasma nitriding was carried out at a range of conditions including nitrogen content temperature and time Surface characterization was performed by microhardness apparenthardness X ray diffraction scanning electron microscopy and optical microscopy Impact energy was considered as a standard method to evaluate the reduction in toughness due tonitriding The results showed that microhardness profile was shifted to higher values by increasingnitrogen content Meanwhile the impact energy was almost similar for different cycles Therefore higher nitrogen content was considered beneficial for such alloys Nitriding at different temperatures showed that the highest surface hardness and maximumhardness was obtained at 450 C but the highest case depth was observed at 500 C At550 c the microhardness profile dropped to lower values and case depth decreasedconsiderably Furthermore core softening was more pronounced at 550 c in comparisonwith other temperatures This is probably related to an increasing distance betweencementite layers in bainite microstructure The microhardness profiles of the two alloys were almost similar in all cycles andmanganese did not show any considerable effect on the hardness of diffusion zone Theoptimum nitriding conditions were considered to be 80N2 20H2and 500 C The discs werenitrided under these conditions but at time intervals of 5 10 and 20 hrs Wear tests wereperformed under dry sliding conditions by pin on disc method Nitriding improved thespecific wear rate of the alloys 1 2 orders in comparison with untreated discs It was shown that for sintered steel similar to most wrought steels the specific wear rate of1 x 10 8 to 2 x 10 8 mm3IN mm could be considered the transition between mild and severewears It was shown that for untreated specimens the worn surfaces were severelydamaged the amount of metallic wear particles were increased representing the severemode of wear The specific wear rate was 10 7mm3IN mm that confirmed the observations Nitriding the samples protected the alloy surface and no considerable damage wasobserved the amount of wear particles decreased and it became oxidative whichrepresentedthe mild wear regime The specific wear rates were 10 9to 10 8mm3IN mm thatpredicted mild wear or mild severe transition wear this was in agreement with themicroscopical observations et l L It u i l tI J ij
استاد راهنما :
فخرالدين اشرفي زاده
استاد داور :
كمال جانقربان، محمدعلي گلعذار، مهدي صالحي، غلامرضا آريانپور
