Proses Quenching and Partitioning Terhadap Sifat Mekanik Baja Karbon Medium

Baja WRM 1045 adalah baja karbon sedang yang menawarkan sifat mekanik yang baik dan diterapkan untuk industri otomotif seperti poros engkol. Menurut JIS G4051 bahwa sifat mekanik untuk poros engkol diharapkan memiliki kekuatan luluh ~ 490 MPa, kekuatan tarik minimum, dan  perpanjangan 686 MPa dan 17%. Dalam penelitian ini, baja WRM 1045 diproses melalui proses Quenching and Partitioning (Q&P). Itu dilakukan dengan variasi waktu penahanan  30 dan 60 menit selama austenitisasi dan suhu partisi 225, 250, 275, dan 300 ℃. Pengujian tarik, uji kekerasan dan metalografi dilakukan untuk menentukan sifat mekanik dan struktur mikro baja WRM KS1045. Hasil penelitian menunjukkan bahwa sifat mekanik menurun dengan meningkatnya suhu partisi dan waktu penahanan austenit. Semakin tinggi sifat mekanik dicapai setelah waktu tahan austenit 60 menit dan suhu partisi 275 ℃ dengan kekuatan luluh 520,70 MPa, kekuatan tarik 784,63 MPa, perpanjangan 15%, dan kekerasan 93,33 HRB. Analisis struktur mikro optik terdiri dari martensit dan retensi austenit setelah proses Q&P

Controlling Risks Through Ergonomics Participatory In Industry Of Processed Meat Products Certified Halal

The halal certified processed meat industry in Banten province reaches 147 industries spread across eight districts / cities in Banten Province. Evaluation of the HAS-2300 implementation has been carried out periodically, but there are still various weaknesses that result in the company's performance being not optimal. Risk control has also been implemented to anticipate various contaminants and activities that may harm employees, but there are still errors in implementing work procedures. Risk control through participatory ergonomics is needed to find the most critical point in the halal meat processing industry. Respondents in this study were determined based on purposive sampling technique. The results showed that the greatest risk comes from social-technical factors, namely that humans are the main factor at the critical point of materials. Although the process of slaughter has been assisted by the adoption of technology, the existence of humans is not replaced by machines. Animal slaughter techniques are the key to meeting the critical point of meat product

Fabrication of the Ti/SiC Based Composites by Self-Propagating High Temperature Synthesis

Metal matrix composites (MMC) consists of matrix and reinforcement. Aluminium (Al) and titanium (Ti) are mostly used as a matrix, while ceramics like silicon carbide (SiC) play role as a reinforcement where magnesium (Mg) act as wetting agent. Al/Ti alloys often used in the applications of powder-shaped. Nevertheless these materials are very suitable for the processes that are using a simple and novel method called self-propagating high temperature synthesis (SHS). Based on it, some of the advanced materials such as alloys, advanced ceramics and intermetallic compounds have been focused on SHS process. The SHS compacting process is carried out in stages according of the temperatures helping by compacting force applied. Our research work will be focused on the fabrication composites based Ti/SiC by using SHS process. The microstructure of the Ti/SiC based composites was investigated by using optical microscope. The micro-hardness testing device has been used to determine the mechanical properties of Ti/SiC based composites. The relationships between reaction of the Ti and SiC have been investigated to obtain the value of the composite properties and the bond between Ti and SiC. Ti/SiC based composites were obtained with improved properties

Cardiac Cell Regeneration in Zebrafish A Systematic Review Study.

Objective: This research aims to increase the level and quality of the information acquired from 90 previously conducted studies regarding zebrafish heart regeneration and to summarize the best and latest information as well as the methods gleaned from those studies, which will allow us to determine the best ways to rebuild cardiac tissue in zebrafish. Methods: This study was conducted under the PRISMA guidelines. The search for primary research articles was conducted using PubMed, Web of science, and Mendeley. We used the latest update of Microsoft office Excel, Of the total 1158 results, 1066 were dropped according to the criteria for exclusion. The selected results included previously published and unpublished studies on cardiac cell regeneration in zebrafish from 2012 to 2022. Results: 90 studies met the inclusion criteria. Out of these, 43 used the AR method, 36 used cryoinjury, and 16 used genetic amputation. All methods used were based on selected heart sections, not the whole heart. The primary evaluation technique used in the included studies was histology, either alone or in combination with other methods. Acid Fuchsin Orange G (AFOG), Masson's Trichrome (MT), Hematoxylin/Eosin (HE), immunofluorescence (IF), and in situ hybridization (ISH) were the main histological techniques employed to assess heart regrowth and regeneration. Conclusion: This study may have a risk of bias due to the qualitative and quantitative data that was selected. Further research can help understand and utilize zebrafish regeneration genes in humans

Corrosion behavior of pure magnesium processed by accumulative roll bonding for biomaterial application

583-590Magnesium is one of the materials that can be used as an implant for the human body. It is because the daily intake of magnesium for an adult is 240-420 mg/day. Also, the elastic modulus (41 – 45 GPa) and density (1.74 g/cm3) of magnesium is closer to that of natural bone. However, pure magnesium in the as-cast condition has a very fast corrosion rate, 2,89mmPY in 0.9% NaCl solution. Accumulative roll bonding (ARB) is done in this recent study to improve the corrosion rate of pure magnesium. ARB is one of the severe plastic deformations (SPD) method, which provides the possibility to obtain high strained materials without a macroscopic change after a cyclic roll-bonding process (stacking, preheating and rolling). Magnesium is annealed at 250°C and 350°C for 25 minutes, and then the ARB process is done with variation; one, two, three and four cycles. The composition was tested using SEM-EDS, showing that the content of a pure magnesium plate (as annealed) is 99.77%. The grain size is observed using the optic microscope and measured by ImageJ, while the corrosion rate was measured with an electrochemical and immersion test. The result showed the smallest grain size achieved is 7.204 ± 1,185 μm and that the lowest corrosion rate is 0,0012mmPY. The polarization resistance determined the thickness and the ability of passivation area obtained with the increasing number of ARB cycles. The higher plastic deformation is recommended for improve the corrosion resistance of the metallic material for future works

Production of Ultrafine-Grained Aluminum Alloys with Unusual Mechanical Properties Using High-Pressure Torsion

主1-参0工学_材料物性工

高圧ねじり加工超微細粒アルミニウム合金の特異な機械的特性発現に関する研究

主1-参0工学_材料物性工

Kartläggning av nyanlända elever

I klassrummet möter lärarna barn med olika kulturer och bakgrunder. Det kan vara en utmaning för lärarna att noggrant planera och genomföra undervisningen på så sätt att alla barn i klassen får det de behöver för att främja deras lärande och kunskapsutveckling. Syftet med denna studie är att undersöka och beskriva hur ett antal skolor gör pedagogiska kartläggningar på nyanlända elevernas kunskaper och färdigheter, och hur de använder resultatet av kartläggningen för att ordna och anpassa undervisningen för nyanlända elever.I denna studie kommer vi att använda en teoretisk del som består av beskrivning av olika teorier om kartläggning av nyanlända elever. Den andra delen består av information och kunskaps insamling som rör kartläggning och en del av det som skrevs kring ämnet, försöker vi hitta gemensamheter i de olika studier om kartläggning och se vilka svårigheter man bemöter. Frågorna är de samma för alla och ger möjligheter till intervjuade personer att svara fritt. Intervjupersonerna är verksamma lärare och specialpedagoger. I intervjuerna får pedagogerna berättar om sina erfarenheter om kartläggning.Resultatet från intervjuerna med pedagoger visar tydligt att kartläggning ger större förståelse att känna igen nyanlända elevernas förmågor i de olika skolämnena. Dessutom hjälper kartläggningen att genomföra en väl planerade undervisningen för att öka elevernas språkutveckling

Production of nanograined intermetallics using high-pressure torsion

Formation of intermetallics is generally feasible at high temperatures when the lattice diffusion is fast enough to form the ordered phases. This study shows that nanograined intermetallics are formed at a low temperature as 573 K in Al- 25 mol% Ni, Al- 50 mol.% Ni and Al- 50 mol% Ti powder mixtures through powder consolidation using high-pressure torsion (HPT). For the three compositions, the hardness gradually increases with straining but saturates to the levels as high as 550-920 Hv. In addition to the high hardness, the TiAl material exhibits high yield strength as ~3 GPa with good ductility as ~23%, when they are examined by micropillar compression tests. X-ray diffraction analysis and high-resolution transmission electron microscopy reveal that the significant increase in hardness and strength is due to the formation of nanograined intermetallics such as Al3Ni, Al3Ni2, TiAl3, TiAl2 and TiAl with average grain sizes of 20-40 nm