Cahya Sutowo

Microstructure and mechanical properties of as-cast Ti-Mo-xCr alloy for biomedical application

Beta Ti alloys is one of the most attractive biomaterials due to their better corrosion resistance, biocompatibility, greater specific strength and lower elastic modulus than stainless steels and Co-Cr based alloys. Cr is the strong beta Ti stabilizer and has lower density than Nb, Sn and Ta. In this study As cast Ti-12Mo and Ti-12-xCr with Cr content range 1, 3, 5, and 10 wt.% prepared by using arc melting vacuum-pressure casting were investigated. The as cast Ti-Mo and Ti-Mo-xCr examined using X-ray diffraction (XRD), optical microscope (OM) and Vickers hardness tester. Experimental result indicate Ti-12Mo-xNb match for β phase peaks but TiO2 phase occurred in all alloys. The vickers hardness values of all the Ti-12Mo-xCr alloys are higher than HV 1000. The optical microscope investigation indicate Cr content influence Ti-Mo-xCr microstructure.

INFLUENCE OF CARBON AND NITROGEN ADDITION ON THE CORROSION RESISTANCE OF Co-28Cr-6Mo-0,8Si-0,8Mn-0,4Fe-0,2Ni ALLOYS

Cobalt alloys is one of the implant materials that is used in orthopedic and dentistry, because of its biocompatibility, good mechanical properties, and high corrosion resistance. The mechanical properties and corrosion resistance can be enhanced by thermomechanical treatment and addition of alloying element. Carbon and nitrogen were added to enhance mechanical properties and high corrosion resistance. Effect of carbon variation and nitrogen to the corrosion resistance in Co-Cr-Mo (CCM) alloys were measured by corrosion measurement system (CMS) device in Hank’s Solutions after thermomechanical treatment process. Corrosion rate of Co-Cr-Mo alloys with carbon variation dropped to 5.8 x 10 -4 mmpy and 5.2 x 10 -4 mmpy with carbon variation and nitrogen. Decreasing corrosion rate indicated that the corrosion resistance of alloys is increased with the addition of carbon and nitrogen.

The influence of solution treatment temperature on microstructure and mechanical properties of Ti6Al6Nb

The alpha-betaTi-6Al-6Nb was manufactured by vacuum arc re-melting furnace with non consumable tungsten electrode. The ingot was homogenized and rolled to plates, followed by solution treatment. Microstructure evolution and its influence to mechanical properties was investigated, using optical microscope, hardness test, and Young’s modulus measurements. The resultshowedthat Ti6Al6Nb alloy after solution treatment at 1050 °C has full equiaxed microstructure. The solution treatment exhibit Young’s modulus 115 to 123 GPA and 36.27 to 44.03 HRc. The Young’s modulus of Ti-6Al-6Nb after solution treatment was closed to conventional Ti-6Al-4V.The alpha-betaTi-6Al-6Nb was manufactured by vacuum arc re-melting furnace with non consumable tungsten electrode. The ingot was homogenized and rolled to plates, followed by solution treatment. Microstructure evolution and its influence to mechanical properties was investigated, using optical microscope, hardness test, and Young’s modulus measurements. The resultshowedthat Ti6Al6Nb alloy after solution treatment at 1050 °C has full equiaxed microstructure. The solution treatment exhibit Young’s modulus 115 to 123 GPA and 36.27 to 44.03 HRc. The Young’s modulus of Ti-6Al-6Nb after solution treatment was closed to conventional Ti-6Al-4V.

Effect of quenching medium on the microstructure of hot rolled Ti-6Al-6Nb alloy for medical application

The Ti-6Al-6Nb alloy has been used as bone plate in biomedical application. But, its modulus elasticity still lies above its cortical-bone, which causes stress shielding. An alternative process for reduce modulus of elasticity by means of treatment solutions with heating β-transus temperature follows with rapid cooling for obtaining high % intensity of β-phase fractions. In this study the Ti-6Al-6Nb as-cast alloys were homogenized at 1050 °C for 12 hours, then hot-rolled with a reduction 60% (from 10mm to 4u2005mm thickness) at 1000 °C and then dissolved at 1100 °C for 2 hours and then cooled by water, oil and air. The microstructural observations were performed with OM and SEM-EDS. The phase analyzes were observed by XRD test and mechanical properties observed by Ultrasonic test. The observation result shows the elasticity modulus value in alloys which being ST with cooling is 106,71u2005GPa. This is consistent with the observation of the microstructure that the presence of β-transformed and it is also in accordance with the XRD analysis and the intensity of the phase fraction, where the peak and% intensity of the β (35%) phase fraction increase in alloys which ST and oil quench.The Ti-6Al-6Nb alloy has been used as bone plate in biomedical application. But, its modulus elasticity still lies above its cortical-bone, which causes stress shielding. An alternative process for reduce modulus of elasticity by means of treatment solutions with heating β-transus temperature follows with rapid cooling for obtaining high % intensity of β-phase fractions. In this study the Ti-6Al-6Nb as-cast alloys were homogenized at 1050 °C for 12 hours, then hot-rolled with a reduction 60% (from 10mm to 4u2005mm thickness) at 1000 °C and then dissolved at 1100 °C for 2 hours and then cooled by water, oil and air. The microstructural observations were performed with OM and SEM-EDS. The phase analyzes were observed by XRD test and mechanical properties observed by Ultrasonic test. The observation result shows the elasticity modulus value in alloys which being ST with cooling is 106,71u2005GPa. This is consistent with the observation of the microstructure that the presence of β-transformed and it is also in accord...

Mechanical Properties, Microstructure, and Bicompatibility of Ti-6Al-6Mo for Biomedical Application

The Ti-6Al-6Mo alloy was arc melted eight times from pure Ti, Al, and Mo. The Ti-6Al-6Mo were analyzed by optical microscope, SEM EDS, XRD and Vickers Hardness Tester. Corrosion test were performed using Hank’s solution at 37 °C and pH 7.4. The optical micrograph showed a homogeneous structure of this alloy. The microstructure of Ti 6Al-6Mo was basketweave with uf061 lath. The map of Ti, Al and Mo showed a homogeneous distribution of this alloy. The XRD analysis showed that the α and β phase occured. The Vickers hardness value of Ti6Al6Nb was 398.7 HV, higher than Ti pure. The corrosion rate of as cast Ti-6Al-6Mo was 0.0016 mmpy (mm/year). The result showed that this alloy could pottentially used for biomedical application.Key words : Ti6Al6Mo, Arc melted, Biomedical application IOP Conference Proceeding ICAMST 2016

PENGARUH VARIASI BERAT FOAMING AGENT CaH2 TERHADAP KARAKTERISTIK PADUAN Mg-Ca-Zn METAL SELULAR BERBASIS SISTEM Mg-Zn-CaH2

THE EFFECTS OF FOAMING AGENT CONTENT CaH2 ON THE CHARACTERISTIC OF METAL CELLULAR Mg-Ca-Zn ALLOYS BASED ON Mg-Zn-CaH2 SYSTEM. In this study, cellular metal with the open-cell structure of Mg-Ca-Zn alloy based on Mg-CaH2-Zn system was prepared and investigated. The addition of CaH2 was intended to trigger the release of hydrogen gas from CaH2 of the alloy powder particles so as to encourage the formation of pores. Alloy composition was selected by -2% by weight Mg Zn 1.2% by weight of CaH2; and Mg -2 wt% Zn 10% by weight of CaH2. The results of the alloy powder after milling and compacting were tested by Differential Thermal Analysis (DTA), while the results of sintered green-compacts were characterized by XRD (X-ray diffraction) and microstructure observation using SEM-EDS (scanning electron microscopy-energy dispersive spectroscopy). From the analysis using XRD, the process of mechanically mixing powders of Mg-Ca-Zn-Mg CaH2 produced elemental phase of Zn phase, Mg phase (HCP) and binary phase of Mg2Ca besides the ternary Mg-Ca-Zn.

Processing of porous Mg-Zn-Ca alloy via powder metallurgy

Mg-Zn-Ca alloy is one of magnesium alloys that has been investigated for its potential in metal foam implant application. In this study, porous Mg-Zn-Ca alloy was prepared by powder metallurgy method, comprising of green compact fabrication and its sintering process. Calcium hydride (CaH2) was added as a foaming agent. The composition of Mg-Zn-Ca alloy was varied (1-30%wt CaH2, and 1 variation with 9%wt Ca addition; while Zn constant) to study the effect of foaming agent and calcium addition on phase formation and structural properties of Porous Mg alloy. Sintering process was done in a tube furnace under argon atmosphere in 520°C for 2 hours. The as-sintered alloys were characterized by scanning electron microscopy (SEM) and also X-Ray diffraction analysis (XRD). Microstructure characterization showed different CaH2 content in the alloy would give different type of pores. There was a tendency of increasing pore size and rough grain along with higher content of CaH2. Further, XRD analysis indicated that s...

FENOMENA TEMPER EMBRITTLEMENT PADA BAJA MARTENSITIK AISI 410 UNTUK APLIKASI STEM GATE VALVE 20” CLASS 150 GRADE WCB[Temper Embrittlement Phenomena of AISI 410 Martensitic Steel for Stem Gate Valve 20” Class 150 Grade WCB]

Temper embrittlement is a phenomenon that will decrease the toughness of steel due to tempering process at a certain temperature range. This phenomenon has been found in martensitic steel. This research is investigated the failure in stem gate valve of crude oil pipeline system. The stem gate valve material is madexa0 of stainless steel AISI 410. Several examinations were done to study cause of failure in stem gate valve such as visual inspection, chemical composition test using OES (optical emission spectrometer) and EDS (energy dispersive spectrometry), metallography observation by using optical microscopy (OM) and SEM (scanning electron microscopy), fractography using SEM, and Rockwell hardness test. Chemical composition test result on stem gate valve showed 13,65-13,67 wt.% Cr. The content of Cr in stem material is out from the required composition of AISI standard with the requirement of Cr amount 13,5 wt.%. Fractography result on the surface of failure stem area by SEM was observed intergranular crack followed by secondary crack. Its indicated that stem gate valve failure was caused by temper embrittlement due to tempering process. Abstrak Temper embrittlement merupakan fenomena penurunan kekuatan dari material baja yang disebabkan oleh proses tempering pada rentang temperatur tertentu. Beberapa kasus temper embrittlement ditemukan pada baja martensitik. Pada studi kali ini dilakukan pengamatan terhadap stem gate valve pada sistem perpipaan minyak mentah yang mengalami patah. Stem gate valve tersebut terbuat dari baja tahan karat martensitik tipe AISI 410. Kemudian dilakukan beberapa pengujian untuk mengetahui proses terjadinya patah pada stem gate valve yang meliputi pemeriksaan visual, analisa komposisi kimia dengan OES (optical emission spectrometer) dan EDS (energy dispersive spectrometry), pengamatan metalografi dengan OM (optical microscopy) dan SEM (scanning electron microscopy), fraktografi dengan SEM, serta uji keras Rockwell. Hasil pemeriksaan pada stem gate valve menunjukkan komposisi Cr adalah 13,65-13,67 % berat atau melebihi batas atas standar AISI 410 yaitu 13,5 %berat. Dari pengamatan struktur mikro diketahui material stem gate valve dalam kondisi telah dilakukan proses tempering dan teramati adanya secondary crack. Dari pengamatan fraktografi diketahui jenis retakan pada permukaan stem yang patah adalah retakan antar butir (intergranular crack) yang mengindikasikan terjadinya proses temper embrittlement pada saat proses tempering material stem gate valve.