OTOMOTİV ENDÜSTRİSİNDE KULLANILAN KAPORTA SACININ PLAZMA ARK KAYNAĞI

Bu çalışmada, yüksek dayanımlı, düşük alaşımlı (YDDA) galvanizli sac malzemeler, plazma ark kaynak (PTA) yöntemiyle birleştirilmiştir. Çalışmada, sabit ilerleme hızı,  plazma ve koruyucu gaz debisi şartlarında, akım şiddetinin bağlantıların kaynak nüfuziyeti üzerindeki etkisi deneysel olarak araştırılmıştır. Birleştirilmiş numunelerin ara yüzeylerinde meydana gelen yapısal değişimler, optik mikroskop ile incelenmiş ve mikrosertlik değerleri ölçülmüştür. Sonuç olarak, PTA yöntemi ile tam nüfuziyet elde edilmiş ve akım şiddetinin mikrosertlik değerlerini artırdığı tespit edilmiştir

Synthesis and structural characterization of Fe based Ti+Ni3Al+Al2O3 reinforcement composite produced by mechanical alloying

The Fe-based Ti+Ni3Al+Al2O3 powder mixture is mechanically alloyed in a Spex ball mill. Composites with Fe-based Ti+Ni3Al+Al2O3 addition were produced at 1000 degrees C sintering temperature for 1 h sintering time. The metallurgical properties of these composites were examined by scanning electron microscopy (SEM), optical microscopy (OM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and microhardness analyses. The final products produced by mechanical alloying were nanocrystalline nickel-rich solid solution and the size of average crystallite was in the range of a few nanometres. Titanium content in the reinforcement increased microhardness values of composite. The produced composites included Fe3Al, TiAl, NiAl, Al3Ni2, Al2O3 and Fe3O phases.KAYALAR copper group; KAYALAR copper Industry and Trade Incorporated CompanyThis work was financially supported by the KAYALAR copper group. The authors are grateful to KAYALAR copper Industry and Trade Incorporated Company for their financial assistance in conducting the experiments

MICROSTRUCTURE AND WEAR PROPERTIES OF FeCrC, FeW AND FeTi MODIFIED IRON BASED ALLOY COATING DEPOSITED BY PTA PROCESS ON AISI 430 STEEL

The plasma transferred arc (PTA) process was used for developing wear resistance of AISI 430 steel substrate. Appropriate quantities of FeCrC, FeW and FeTi powders were combined to create conditions that synthesized M7C3 particles into reinforced Fe-based composite surface coating. The phase transformations on new created coated surfaces were comprehensively examined by using a combination of scanning electron microscopy (SEM), microanalysis by energy dispersive spectrometry (EDS), X-Ray diffraction (XRD), microhardness and abrasive wear tests. The microstructure studies of the superficial layers of the coating revealed presence of a mixture of the dendritic phase structure of austenite (gamma) and fine eutectic M7C3 carbides. The results show that; the concentrations of the elements (Cr, W, Ti) added as ferroalloys, the size of dendrites formed in the coated surface, the change of hardness of the coated surfaces, the carbide volume rate and thickness of the coating changed by the variation of the processing parameters (ratio of reinforcement particulates and heat input)

AISI 1040 ÇELİK ÇİFTİNİN KPTA KAYNAĞINDA PLAZMA GAZ DEBİSİNİN NÜFUZİYET DERİNLİĞİ ÜZERİNE ETKİSİ

Bu çalışmada, 10 mm kalınlığında AISI 1040 çelik çifti alın pozisyonunda, kaynak ağzı açmaksızın, anahtar deliği plazma transfer ark (KPTA) kaynak yöntemiyle birleştirilmiştir. Kaynak sonrası, numunelerin ara yüzeyinde meydana gelen yapısal değişim optik mikroskop ve mikrosertlik test yardımı ile incelenmiştir. Ayrıca; kaynaklı numunelerin bağlantı mukavemetini belirlemek amacıyla, çentik darbe testi uygulanmıştır. Sonuç olarak, plazma gaz debisindeki artış nüfuziyet derinliğini artırmıştır

Effect of Ni on microstructure and wear behaviour of 13Cr-W-Mo-2C white cast iron

The effect of Ni concentration on the microstructure and wear performance of 13Cr-(0.5-7.0)Ni-W-Mo-Mn-2C white cast iron subjected to homogenization heat treatment was examined. Concentration of Ni was altered in the range 0.5-7.0 wt.% to obtain a stable microstructure against for dry sliding wear resistance as long sliding distance. The effect of Ni on the microstructure was analysed by X-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, elemental mapping and hardness. The wear performances were tested under the loads of 40, 90 and 140 N. Differential thermal analysis of samples with dissimilar Ni values was performed. The increase of Ni concentration decreased the secondary arm spacing of dendrites, refined the dendritic structure and raised the eutectic carbide ratio. The greatest wear performance was obtained for the sample having Ni over 6 wt.%

Investigation on mechanical properties of solution strengthened and austempered ferritic ductile irons

The aim of this study was to investigate the influence of austempering on the mechanical properties of solution-strengthened ferritic cast ductile irons. The microstructural examinations of the samples were conducted using optical microscopy, scanning electron microscopy, and X-ray diffraction. Hardness, impact, and tensile tests were performed to determine the mechanical features. After the impact test, the fracture surface morphology was analyzed with scanning electron microscopy. The austempering results showed that the matrix structure with 70 % ferrite and 30 % bainite had the highest fracture toughness and yield strength. The ausferrite phase in microstructure played a positive role in ductility, toughness, and strain rates. The mechanical properties were strongly related to the amounts of ausferrite and retained ferrite ratio.SIO Automotive groupThis work was supported by the SIO Automotive group. The authors are grateful to SIO automotive for their assistance in conducting the experiments

Effect of carbides on the wear resistance of white cast iron alloyed with 12.7 wt.-% Cr and nickel

White cast iron with about 12.7 wt.-% chromium was alloyed with Ni, W and Mo for heat treatment applications. Heat treatments were performed at a range of 850-1050 degrees C for 1 h in order to distribute M7C3 carbides homogeneously in an environment of high wear resistance. The contents of the C, Cr, Ni, Mo, Mn and Si elements selected for the alloys were similar, though a 6 wt.-% nickel concentration was chosen. Microstructural changes in the specimens were examined by scanning electron microscopy (SEM) and optical microscopy (OM). Macro-hardness, average carbide size and volume fraction were analyzed. Wear tests were carried out under different loads of 10, 20 and 30 N. It was seen that heat treatment changed the carbide size and homogeneous distribution of the carbides. Moreover, the addition of nickel to HCrWCI increased fracture toughness and reduced the wear rate