Hasil Pencarian  ::  Simpan CSV :: Kembali

"All metals have unique advantages and disadvantages in terms of their mechanical properties. Advantages such as flexibility are needed for construction and for the manufacture of sophisticated products. Some industries have improved the mechanical properties of metals by welding dissimilar ones together, such as aluminum alloy (AA) to stainless steel (SS) to reduce vehicle weights in order to improve fuel consumption. However, little research has been conducted on using micro resistance spot welding (mRSW) to join SS and Al by inserting a zinc (Zn) sheet between them as an interlayer. In this study, the mechanical properties of the weldment are tested using a shear test and Vickers micro hardness test. The results are compared using welding times of 6, 8 and 10 cycle times (CTs) and welding currents of 5 and 8 kA during the mRSW process. It is found that the SS, Zn and AA sheets could be joined with mRSW using an 8 kAA welding current and a 6 CT welding time. The micro hardness in the AA-Zn dissimilar joint increased relative to SS-Zn. Using a Zn sheet also improved displacement in the tensile shear test; however, it also increased the hardness of the diffusion zone."

"Resistance spot welding (RSW) is widely used in industries such as the aerospace, automotive, and electrical application industries. RSW is very useful for joining aluminum and its welding parameters lead to good quality joints. This research studied the influence of the welding parameters, such as welding current, welding time, and the electrode force, of micro resistance spot welding (MRSW) on the mechanical properties and fracture of a nugget of aluminum alloy (AA) 1100. AA 1100 plate with a thickness of 0.4 mm was used in this experiment. An alternating current (AC) RSW machine and electrode were used in this study. The welding parameters used in this study are welding current, welding time, and electrode force. Holding time is assumed to be constant. The welding time values of 6 CT, 8 CT, and 10 CT were combined with a welding current of 8 kV, and electrode forces of 32 kg, 42 kg, and 52 kg. The results showed that by increasing the electrode force, the load rate decreases, and the elongation distance tends to decrease, except for the electrode force of 52 Kg. The effect of the electrode force on the diameter and thickness of the weld nugget was not significant."

"Penelitian ini bertujuan untuk mengetahui pengaruh kandungan nikel dalam elektroda terhadap sifat mekanis dan mikrostruktur pengelasan baja pelat SM570TMC dan AH36. Pengelasan material tersebut menggunakan metode Flux Cored Arc Welding (FCAW) dengan kawat las yang memiliki kandungan nikel 0%, 1%, dan 1,5%. Hasil dari pengelasan diteliti dengan pengujian tak rusak (MPT, UT) dan rusak (Hardness Vickers, impact charpy, pengamatan mikrografi (makro, mikro, SEM, EDS, OES)). Pengujian dilakukan pada area base metal (BM), Heat Affected Zone (HAZ) dan Weld Metal (WM). Pengujian impact charpy dilakukan pada temperatur 25⁰C, 0⁰C, dan -20⁰C. Pengujian NDT tidak mempengaruhi kualitas lasan. Hasil pengujian kekerasan pada penambahan 1% nikel material AH36 maksimum sebesar 190 HV dan minimum 163 HV sedangkan untuk material SM570TMC maksimum sebesar 172 HV dan minimum 154 HV. Material AH36 mempunyai nilai ketangguhan impak pada temperatur 0⁰C sebesar 280 J dan pada temperatur-20⁰C sebesar 200 J diarea HAZ. Material SM570TMC nilai ketangguhan impak sebesar 385 J pada temperatur 0⁰C dan 276 J pada temperatur -20⁰C diarea HAZ. Dengan penambahan 1% nikel menunjukkan dalam pengamatan mikro menghasilkan butiran yang lebih halus bila dibandingkan penambahan nikel 0 dan 1,5% sehingga mampu meningkatkan nilai ketangguhannya pada material AH36 dan SM570TMC terutama pada temperatur 0⁰Cdan -20⁰C.

---

This study aims to determine the effect of nickel content in electrodes on the mechanical and microstructure properties of welding steel plates SM570TMC and AH36. Welding of the material uses the method of Flux Cored Arc Welding (FCAW) with welding wire which has a nickel content of 0%, 1%, and 1.5%. The results of welding were examined by non-destructive testing (MPT, UT) and damaged (Vickers Hardness, charpy impact, micrographic observations (macro, micro, SEM, EDS, OES)). Tests were carried out on the base metal area (BM), Heat Affected Zone (HAZ) and Weld Metal (WM). Charpy impact testing is carried out at temperatures of 250C, 00C, and -200C. NDT testing does not affect weld quality. The hardness test results on the addition of 1% nickel AH36 material to a maximum of 190 HV and a minimum of 163 HV while the SM570TMC material is a maximum of 172 HV and a minimum of 154 HV. AH36 material has an impact toughness value at a temperature of 0⁰C of 280 J and at a temperature of -20⁰C of 200 J at HAZ area. Material of SM570TMC impact resistance value was 385 J at temperatures of 0⁰C and 276 J at -20⁰C at HAZ. With the addition of 1% nickel, the micro-observation produced finer grains when compared to the addition of 0 and 1.5% nickel so as to increase the toughness value of AH36 and SM570TMC materials, especially at temperatures of 0⁰C and -20⁰C."

"Eksperimen pengelasan dan analisis termal dengan menggunakan Finite Element Method dilakukan pada material baja AH36 dengan membandingkan antara proses pengelasan Flux Cored Arc Welding dan Gas Metal Arc Welding. Tujuan dari penelitian ini adalah untuk membandingkan sifat mekanis dan struktur mikro lasan FCAW dan GMAW dari baja HSS AH36 dan analisis termal menggunakan simulasi FEM dengan perangkat lunak ANSYS. Penentuan kekuatan mekanik dari hasil pengelasan AH36 dilakukan dengan menggunakan microhardness Vickers dan Charpy V-notch impact tester. Scanning Electron Microscopy dan mikroskop optik menjadi alat yang digunakan untuk mengevaluasi evolusi struktur mikro di daerah zona fusi, zona yang terkena dampak panas dan logam dasar. Nilai distorsi yang diukur sangat kecil yang sesuai dengan pengamatan aktual pada hasil lasan yang tidak terjadi distorsi. Kontur dari panas akibat pemanasan dapat terlihat dari sumber panas yang menyebar ke semua arah. Nilai kekerasan yang terukur pada logam induk lebih kecil dibandingkan pada area terkena panas (HAZ) kemudian nilai kekerasannya turun pada daerah lasan. Nilai ketangguhan pada proses GMAW lebih tinggi dari proses FCAW karena kandungan nikel yang terdapat pada kawat las.

---

Welding and thermal analysis experiments using Finite Element Method were carried out on AH36 steel by comparing between the welding process of Flux Cored Arc Welding and Gas Metal Arc Welding. The purpose of this study was to compare the mechanical properties and microstructure of FCAW and GMAW welds from AH36 HSS steel and thermal analysis using FEM simulation with ANSYS software. Determination of mechanical strength from welding results was done using the Vickers microhardness and Charpy V-notch impact tester. Scanning Electron Microscopy and optical microscopy are tools used to evaluate microstructure in the fusion zone, a zone that discusses heat evolution and base metals. Small distortion value according to the actual results of the weld results that no distortion has been detected. Contour of heat that occurred can be seen from the heat source that spreads in all directions. The hardness values measured on the base metal are smaller than those in the heat approved area (HAZ) then the value of in the weld area. The toughness value in the GMAW process is higher than that of the FCAW process because of the nickel content needed in welding wire."

"Micro Resistance Spot Welding (MRSW) merupakan metode pengelasan yang banyak digunakan di industri manufaktur dikarenakan prosesnya yang cepat, efisien secara ekonomi, dapat diotomatisasi, dan dapat digunakan untuk pelat dengan ketebalan rendah. Pelat paduan aluminium dan brass, yaitu AA 1100 dan CuZn30 dengan ketebalan rendah merupakan bahan yang dewasa ini banyak digunakan dalam industri manufaktur dikarenakan sifatnya yang ringan dengan kekuatan mekanis yang baik. Belum terdapat penelitian yang membahas mengenai parameter optimum dari mRSW untuk pengelasan AA 1100 dan CuZn30. Dalam penelitian ini, dilakukan pengelasan terhadap pelat AA 1100 dan CuZn30 dengan dimensi 19 mm x 76 mm x 0,4 mm menggunakan instrumen pengelasan micro resistance spot welding (MRSW) otomatis dengan variabel cycle time pengelasan secara berturut-turut sebesar 3, 4, 5, 6, 7, 8, 9, 10 siklus. Karakterisasi hasil las dilakukan lewat analisis pengujian tarik. Pengujian tarik menunjukkan bahwa terjadi peningkatan nilai shear stress pada siklus/cycle time yang lebih besar.

---

Micro Resistance Spot Welding (MRSW) is a welding method that is widely used in the manufacturing industry due to its fast, economically efficient, automable process and can be used for low thickness plates. Aluminum and brass alloy plates, namely AA 1100 and CuZn30 with low thickness are materials that are currently widely used in the manufacturing industry due to their lightweight nature with good mechanical strength. There are no studies that discuss the optimum parameters of micro resistance spot welding (MRSW) for welding AA 1100 and CuZn30. In this study, welding was carried out on the AA 1100 and CuZn30 plates with dimensions of 19 mm x 76 mm x 0.4 mm using an automatic mRSW welding instrument with a variable welding cycle time respectively 3, 4, 5, 6, 7, 8, , 9, 10 cycles. The characterization of welds was carried out through tensile testing. The tensile test shows that there is an increase in the value of shear stress at a greater cycle / cycle time."

"

Di pekerjaan ini, pembelajaran mengenai efek kekasaran permukaan (Ra) terhadap umur kelelahan perpaduan Aluminum 7075-T6 dilakukan. Berdasarkan pekerjaan sebelumnya,  umur kelelahan adalah fungsi dari kekasaran permukaan material/spesimen. Semakin kasar permukaan spesimen, semakin menurun umur kelelahannya. Sebaliknya, semakin halus permukaan specimen maka umur kelelahannya meningkat. Dalam kasus ini, kekasaran (Ra) hanya didapat dari proses machining. Selanjutnya, dibuatlah suatu faktor koreksi yang merupakan perbandingan dari umur kelelahan specimen dengan nilai Ra tertentu terhadap umur kelelahan specimen ideal. Kemudian, digambarkan sebuah kurva nilai faktor koreksi sebagai fungsi dari Ra. Simulasi keausan dengan menggunakan perangkat lunak komersil telah dilakukan untuk memprediksi umur kelelahan pada kondisi ideal. Kemudian, umur kelelahan untuk spesimen dengen berbagai kondisi kekasaran dapat diestimasi dengan factor koreksi yang didapat dari atas. Dapat disimpulkan bahwa kurva yang menunjukan hubungan Ra dengan faktor koreksi dapat digunakan untuk memprediksi umur kelelahan secara efisien saat simulasi.

---

In this work, the effect of surface roughness to the fatigue life of 7075-T6 Aluminum Alloy were studied. The objective is to estimate values of surface factor correction of 7075-T6 Aluminum Alloy and its fatigue life using the obtained correction factors. Based on previous research, a function of fatigue life in terms of surface roughness were obtained. As the surface roughness increases, fatigue life decreases and vice versa. In this case, the Ra value were obtained from machining process only. First, an estimated surface factor correction was obtained as the fatigue limit ratio of specimen with certain Ra value to specimen having ideal surface condition. Then, a function of surface factor correction in terms of Ra were generated. After that, a fatigue simulation was conducted using commercial software to predict fatigue life at the ideal surface condition. Finally, fatigue life for various value of Ra can be estimated using the correction factors obtained. It was concluded that the function of surface factor correction in terms of Ra was applicable to estimate the fatigue life efficiently during simulation.

"

"ABSTRAKBaja tahan karat dua fasa austenitik-feritik (duplex) UNS32205 pada penggunaannya memiliki berbagai keunggulan dalam hal sifat mekanik dan ketahanan korosi. Material duplex tidak terhindar dari pekerjaan pengelasan perbaikan yang kadang diperlukan untuk menghilangkan cacat yang dikarenakan oleh proses pengelasan. Proses pengelasan perbaikan berulang sebanyak empat kali dilakukan dengan menggunakan proses SMAW kemudian dilakukan pengujian nilai impak dan ketahanan korosi sumuran terhadap air laut dengan metode Linear Polarization dengan menggunakan larutan 3.5% NaCl pada temperatur kamar. Uji komposisi, struktur mikro, dan perbandingan dengan literature lain tentang pengelasan perbaikan berulang pada material baja tahan karat dipelajari dan digunakan sebagai pembanding untuk melihat pengaruh perbaikan berulang terhadap sifat mekanis ketangguhan dan ketahanan korosi sumuran. Pengelasan berulang sampai empat kali memberikan nilai ketangguhan dan ketahanan korosi yang lebih rendah dari logam induk, namun masih dalam rentang nilai yang diterima oleh industri. Fasa intermetalik ditemukan pada pengelasan berulang keempat.

---

ABSTRACTDuplex stainless steel UNS32205 on its use has many advantages in terms of mechanical properties and corrosion resistance. Welding repairs are sometimes necessary to eliminate defects caused by welding process. Welding repair process was repeated four times performed using SMAW process then the specimen was impact tested and pitting corrosion resistance to sea water was investigated using Linear Polarization method, using 3.5% NaCl solution at room temperature. Chemical composition test, microstructure examiantion, and comparisons with literature of similar research was done to study the effect of repeated welding repair on the impact toughness properties and pitting corrosion resistance of duplex stainless steel. The value of toughness and corrosion resistance is lower than the base metal, but still within the range of values accepted by the industry, after four times repeated welding repair. Intermetallic phase is found in the fourth repetitive welding."

"Micro Friction Stir Spot Welding (m-FSSW) merupakan pengelasan yang memanfaatkan gesekan serta axial force pada prosesnya. Hasil pengelasan yaitu lap-joint pada satu titik. Penelitian ini menginvestigasi pengaruh parameter pengelasan pada metode pengelasan m-FSSW menggunakan variasi geometri tool dan plunge depth terhadap karakteristik pengelasan. Dilakukan pengukuran temperatur, rotational speed, dan axial force pada proses pengelasan. Hasil penelitian menunjukkan bahwa perbedaan plunge depth (200 µm, 400 µm, 600 µm) memiliki pengaruh signifikan pada temperatur, axial force, dan rotational speed. Semakin dalam penetrasi (plunge depth) dilakukan, temperatur yang dihasilkan semakin tinggi, axial force meningkat dan rotational speed menurun. Variasi geometri tool dan parameter pengelasan juga mempengaruhi kekuatan tarik geser dan geometri hasil pengelasan. Penetrasi yang lebih dalam menghasilkan diameter pengelasan yang lebih lebar dan meningkatkan kekuatan tarik geser. Pada pengujian struktur makro, terlihat beberapa zona pengelasan seperti Stir Zone (SZ), Thermo Mechanically Affected Zone (TMAZ), dan Heat Affected Zone (HAZ). Terdapat pula fenomena seperti Keyhole, Hook, dan EXTD Zone yang terbentuk pada pengelasan m-FSSW. Pengujian kekerasan menggunakan metode micro-hardness vickers menunjukkan bahwa kekerasan yang seragam pada daerah Stir Zone (SZ) mengindikasikan adanya optimal bonding antara dua lembar material. Berdasarkan hasil penelitian, disarankan untuk mengunakan tool 1 (519,18 N) pada plunge depth 600 µm , tool 2 (432,86 N) pada plunge depth 400 µm serta tool 2 (329,79 N) pada plunge depth 200 µm pada pengelasan m-FSSW material AA1100.

---

Micro Friction Stir Spot Welding (m-FSSW) is a welding technique that utilizes friction and axial force in the process to create a lap joint at a single point. This research investigates the influence of welding parameters in m-FSSW, specifically the variation of tool geometry and plunge depth, on the welding characteristics. Measurements of temperature, rotational speed, and axial force were conducted during the welding process. The results of the study indicate that the different plunge depths (200 µm, 400 µm, 600 µm) have a significant impact on temperature, axial force, and rotational speed. Deeper plunge depths result in higher temperatures, increased axial force, and decreased rotational speed. The variation in tool geometry and welding parameters also affects the tensile shear strength and geometry of the weld. Deeper penetrations lead to wider weld diameters and increased tensile shear strength. Macrostructural examination reveals distinct zones in the weld, including the Stir Zone (SZ), Thermo Mechanically Affected Zone (TMAZ), and Heat Affected Zone (HAZ). Phenomena such as Keyhole, Hook, and EXTD Zone are also observed in the m-FSSW process. Micro-hardness Vickers testing demonstrates that uniform hardness in the Stir Zone (SZ) indicates optimal bonding between the two material sheets. Based on the research findings, it is recommended to use Tool 1 (519.18 N) for a plunge depth of 600 µm, Tool 2 (432.86 N) for a plunge depth of 400 µm, and Tool 2 (329.79 N) for a plunge depth of 200 µm in m-FSSW of AA1100 material."

"Studi mengenai perubahan mikrostruktur pada butir ferit dan pengaruhnya terhadap ketahanan korosi pada baja karbon rendah telah dilakukan. Thermomechanical processing (TMP) merupakan sebuah subjek baru dalam ilmu rekayasa material yang mengkombinasikan perlakuan dan temperatur proses terhadap material dengan tujuan mendapatkan material berkualitas tinggi. Dengan memberikan perlakuan canai pada temperatur hangat, akan terbentuk struktur butir ferit yang halus, yang membuat sifat mekanik meningkat, laju korosi menurun, dan kemampuan mengabsorbsi hidrogen juga ikut menurun. Uji polarisasi dan uji HIC dilakukan untuk mengukur laju korosi dan ketahanan penggetasan oleh hidrogen pada bagian spesimen yang searah dan tegak lurus dengan arah canai, dimana spesimen yang dilakukan pengujian adalah baja karbon rendah SS 400 tanpa deformasi dan dengan deformasi canai hangat. Besar deformasi reversible yang diberikan adalah 20%, 20% +20%, 20% +20% +20% and 20% +20% +20% +20% dengan ketebalan awal adalah ho 6 mm. Sebuah mekanisme baru dalam metode canai multi pass reversible juga dilakukan yang disebut metode canai double-side multi pass reversible. Dengan menggunakan metode canai double-side multi pass reversible, diharapkan butir ferit halus yang terbentuk akan terdistribusi seragam diseluruh bagian permukaan.

---

Microstuctural changes of ferrite grains and its relationship with corrosion resistance in low carbon steel were investigated. Thermomechanical processing (TMP) is a new subject in material engineering which is combining treatment and temperature process to material in order to obtain high quality materials. By applying rolling deformation process in warm working temperature, low carbon steel will have fine ferrite grain structures made its mechanical properties increased, its corrosion rate decreased and also its ability to absorb hydrogen decreased.

Polarization test and HIC test were conducted to measure the corrosion rate and hydrogen embrittlement resistance on both parallel and perpendicular specimen to rolling direction (RD) orientation of as-received and plastic-strained warm rolling material as raw material of SS400 low carbon steel. The applied mechanisms of pass deformation are reversible which are 20%, 20% +20%, 20% +20% +20% and 20% +20% +20% +20% with initial thickness ho 6 mm. A new mechanism of multi pass rolling methods was also proposed which is double-side multi pass reversible. By applying double-side multi pass reversible, it is expected that fine ferrite grains will be distributed uniformly in all surface points."

"Pengelasan merupakan salah satu metode penyambungan dalam bidang manufaktur untuk digunakan dalam suatu proses pembuatan produk. Pengelasan adalah penyambungan logam dengan mencairkan logam induk dan logam pengisi dengan atau tanpa tekanan dan dengan atau tanpa logam penambah menghasilkan sambungan pada logam tersebut. Micro Friction Stir Spot Welding MFSSW adalah jenis pengelasan skala mikro yang menggunakan proses gesekan pada suatu titik dalam pengelasannya. Pada penelitian ini mencari pengaruh geometri lasan dari hasil pengelasan MFSSW terhadap sifat mekanik pada Plat Aluminium AA1100. Diperoleh bahwa besaran geometri yaitu, diameter belakang back diamater, luas selimut dan kedalaman hasil pengelasan plunge depth berbanding lurus dengan beban puncak gaya geser Shear Load. Semakin luas, semakin dalam, dan semakin besar diameter belakang back diameter hasil pengelasan maka nilai beban puncak semakin besar, sementara itu untuk deviasi diameter keyhole akibat adanya vibrasi tidak menunjukan pengaruh terhadap shear load.

---

Welding is one of joining method in the field of manufacturing which is used in a product manufacturing process. Welding is the bonding of metal by liquefying the parent metal and filler metal with or without pressure and with or without the adder metal resulting in a connection to the metal. Micro Friction Stir Spot Welding MFSSW is a type of micro scale welding that uses the friction process at a point in its welding. In this research looking for the influence of weld geometry from MFSSW welding result to mechanical properties on AA1100 Aluminum Plate. It is found that the magnitude of the geometry ie, back diameter, blanket width and the depth of the weld plunge depth is directly proportional to the shear load peak. The wider, deeper, and larger back diameter the higher peak load value, meanwhile for the deviation of the keyhole diameter due to vibration, does not show the effect on the shear load. "