Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Steel dengan menggunakan proses pengelasan GTAW terhadap kemampuan tahan korosi pitting SDSS pada lingkungan dengan konsentrasi klorida yang tinggi. Pengelasan dilakukan terhadap empat spesimen dengan gas pelindung yang berbeda, yaitu Ar UHP, Ar 2 N 2, Ar 5 N 2 dan Ar 10 N 2. Hasil lasan pada ke-empat spesimen akan dilakukan pengamatan struktur makro dan mikro dengan mikroskop optik dan SEM-EDS Scanning Electron Microscopic-Energy Dispersive X-ray Spectroscopy , serta pengujian kekerasan, ferite content, pengujian korosi pitting berdasarkan ASTM G48-11 Method E dan potentiodynamic anodic polarization berdasarkan ASTM G5-13 untuk melihat pengaruh nitrogen terhadap struktur mikro dan kemampuan tahan korosi pitting SDSS.

---

This thesis focuses on the effect of nitrogen on the shielding gases for the welding of super duplex stainless steel materials by using GTAW welding process against the pitting corrosion resistance of SDSS in environment with high chloride concentration. Welding was carried out on four specimens with different shielding gases, Ar UHP, Ar 2 N 2, Ar 5 N 2 and Ar 10 N 2. The weldments of the four specimens will be observed for macro and microstructures with optical microscope and SEM EDS Scanning Electron Microscopic Energy Dispersive X ray Spectroscopy , hardness testing, ferrite content, pitting corrosion testing based on ASTM G48 11 Method E and potentiodynamic anodic polarization based on ASTM G5 13 to see the effect of nitrogen on the microstructure and pitting resistance of SDSS.

Abstrak :
Penelitian ini dilakukan untuk mengevaluasi pengaruh dari proses pengelasan perbaikan berulang terhadap evolusi struktur mikro dan sifat mekanik dari super duplex stainless steel(SDSS) UNS S32750. Enam sampel di las dengan proses pengelasan gas tungsten arc welding(GTAW). Sampel pertama disiapkan sebagai original weld(OW), kemudian daerah lasan di eksavasi dengan grinda, dan di preparasi kembali pada area yang sama yang selanjutnya di lakukan pengelasan kembali dengan variasi masukan panas, yaitu masukan panas rendah dan tinggi 1,0 and 1,75 kJ/mm. Sampel repairpertama diberi identifikasi R1-LHI & R1-HHI kemudian proses repairkedua di lakukan sama dengan proses repairpertama dengan identifikasi R2-LHI & R2 HH1 begitu juga dengan R5. Sampel-sampel tersebut selanjutnya di-uji untuk mempelajari perubahan struktur mikro, kandungan ferrit, dan sifat mekanik hasil lasan. Pengujian impak dan kekerasan dilakukan untuk mengkarakterisasi sifat mekanik hasil sambungan, stuktur mikro dan analisa patahan dari sampel impak di teliti menggunakan mikroskop optik (OM) dan Scanning Electron Microscopic-Energy Dispersive X-ray Spectroscopy(SEM-EDS). Hasil penelitian proses pengelasanrepairyang berulang menunjukan terjadinya perubahan yang signifikan terhadap struktur mikro dan sifat mekanik material SDSS. Ukuran butir ferrit pada area HAZ sampel HHI terlihat lebih kasar dibandingkan LHI, mengakibatkan penurunan kekuatan impak hingga 12 J pada sampel R5. Mode patahan ulet terjadi pada sampel OW, R1-LHI, R2-LHI & R1-HHI sedangkan patahan getas terjadi pada sampel R2 HHI & R5, presipitat Cr2N dan fasa sigma juga ditemukan pada foto struktur mikro R5 dimana keduanya dapat menurunkan kekuatan impak hasil lasan. Hasil analisa kandungan ferrit menunjukan pengelasan dengan masukan panas tinggi dapat menurunkan kandungan ferrit dibandingkan dengan masukan panas yang rendah, dan nilai kekerasan rata-rata sampel R1-LHI & R2-LHI terlihat lebih tinggi dari batas kekerasan yang diperbolehkan. Secara keseluruhan pembatasan pengelasan repair hingga repair pertama dengan masukan panas yang sama menghasilkan hasil yang optimal. ......This research is performed to evaluate the effects of repeated weld-repairs on the microstructure evolution and mechanical properties of super duplex stainless steel (SDSS) UNS S32750. Six specimens were welded using gas tungsten arc welding (GTAW) process. The first specimen was prepared as original weld (OW), then weld area was ground, re-beveled on the same location and re-welded with different parameters, low and high heat input 1,0 and 1,75 kJ/mm respectively. The first repair with low heat input and high heat input were called as R1-LHI & R1-HHI and the second repairs were prepared as same as the first repairs and called as R2-LHI & R2 HH1 and also for R5. Specimens with the different condition were studied by examining the changes in microstructures, ferrite content, and the mechanical properties. Impact and hardness test were carried out to characterize the mechanical properties of welded joints, the microstructural and fractography of raptured impact specimens were investigated using optical microscopy (OM) and Scanning Electron Microscopic-Energy Dispersive X-ray Spectroscopy (SEM-EDS). The results showed that microstructures, mechanical properties of SDSS weldments were changing significantly as the effect of repeated repair heat cycle by differences heat input. Ferrite grain size on HHI HAZ specimen was found coarser than LHI, which affected in the reduction of impact value up to 12 J on R5 specimen. Ductile mode fracture was reported occurred on OW, R1-LHI, R2-LHI & R1-HHI and brittle fracture on R2 HHI & R5, Precipitate Cr2N and Sigma phase are also found on R5 microstructure, which may reduce the impact properties of the materials. From ferrite content report shows that welding with HHI reduced the ferrite content compare to LHI samples, and the average hardness values for R1-LHI & R2-LHI were found higher than acceptance. From the results of the examination, limited repair up to the first repair with the same heat input as the original weld was given the optimum results.

Abstrak :
Penelitian efek perlakuan panas pada ketahanan korosi pitting dan struktur mikro pada lasan berulang material super duplex stainless steel UNS S32760 dievaluasi melalui uji korosi pitting, karakterisasi struktur mikro, dan analisis SEM-EDS. Spesimen yang digunakan dalam penelitian ini adalah lasan asli (OW) dan spesimen pengelasan berulang yang diberikan perlakukuan panas, yaitu lasan yang diulang sekali (HR1), lasan yang diulang dua kali (HR2), dan lasan yang diulang tiga kali (HR3). Hasil penelitian menunjukkan bahwa OW menunjukan ketidakseimbangan fraksi ferit-austenit yang signifikan yang mengurangi ketahanan korosi pitting. Perlakuan panas pada temperatur 1100 ºC secara bertahap dapat mengembalikan keseimbangan fraksi ferit-austenit dan melarutkan fasa intermetalik sehingga meningkatkan sifat ketahanan korosi pitting pada spesimen lasan berulang, HR1, HR2, dan HR3. ......The effect of heat treatment on the pitting corrosion resistance and microstructure of UNS S32760 super duplex stainless steel`s repeated welds was investigated through a pitting corrosion test and microstructure characterization. The specimens include an original weld (OW) and three heat-treated specimens, namely a once-repeated weld (HR1), a twice-repeated weld (HR2), and a three-time-repeated weld (HR3). The results show that the OW represents a significant imbalance of ferrite-austenite fractions reducing the pitting corrosion resistance. Conversely, 1100 ºC heat treatment on HR1, HR2, and HR3 gradually returns the equilibrium of ferrite-austenite fractions and dissolve intermetallic phase which improves the pitting corrosion resistance.

Abstrak :
Duplex Stainless steel (DSS) 2205 is wedely used in shipbuilding industry as well as in gas and oil industry because its supenorit N in corrosion resistant and thoughness compared to other metals, during welding process, deformation may occur in DSS 2205. Line heating followed by quenching is often used to relieve deformation following welding process. Line heating applied to DSS 2205 may change microstructure and properties of the steel as well. There are many factors that affect the microstructure change during line heating process and one of them is the number of line heating passes applied to the material at the same location. This reseach examines microstructure and properties of DSS 2205 due to line heating process. Three samples of weld joints were line heated. Each sample were line heated once to and three times respectively in the direction perpendicular to thje weld line. Quanching in fresh water carried out following the line heating process. Each sample was cut into two pieces for metallography, hardness, and ferritescope test. Data obtained from metallography, hardness and ferrtescope tests showed that more line heating passes applied to the same location resulted in creasing ferrite contents increased 21.3% in base metal and 14.6% in weld metal. Ferritescope test showed that ferrite number (FN) increased 6.21 in base metal and 8.13% in weld metal. Hardness number of base metal increased 13 - 71%, 8.85% fusion line and 11.02% weld metal.

Abstrak :
Dalam pengelasan dan tahapan fabrikasi, proses perbaikan pengelasan (repair welding) diperlukan untuk menghilangkan cacat pengelasan. Penelitian ini berfokus pada pengaruh pengelasan perbaikan berulang terhadap struktur mikro, sifat mekanik, dan ketahanan korosi pada lingkungan klorida dari Duplex Stainless Steel (DSS) UNS S31803. Pengelasan perbaikan menggunakan kombinasi pengelasan manual GTAW dan SMAW dilakukan sebanyak tiga kali dengan rata-rata masukan panas sebesar 1,5 – 1,8 KJ/mm. Adapun pengujian yang dilakukan antara lain uji kekerasan mikro Vickers, impak Charpy pada temperatur -40 °C, uji celup pada larutan FeCl₃.6H₂O serta uji polarisasi linier. Selanjutnya, pengamatan area hasil lasan dan terkorosi dilakukan menggunakan SEM serta karakterisasi komposisi kimia lokal menggunakan EDS. Hasil pengujian mekanik menunjukkan bahwa pengelasan perbaikan berulang tidak memberikan pengaruh yang signifikan terhadap sifat mekanik. Sedangkan dari pengujian korosi didapatkan bahwa pengelasan perbaikan berulang menurunkan ketahanan korosi dari hasil lasan DSS ditandai dengan laju korosi tertinggi dan penurunan nilai potensial pitting (E_pit) terbesar pada perbaikan ketiga. Lebih lanjut, pengamatan struktur mikro dilakukan pada hasil lasan dan area terkorosi untuk mengetahui pengaruh pengelasan perbaikan berulang pada DSS UNS S31803, mengingat sampai saat ini pengelasan perbaikan pada DSS dibatasi hanya diperbolehkan satu kali.

---

During welding and also in the stages of fabrication, welding repair required to eliminate the welding defects present. This paper focuses on the effect of multiple repair welding on microstructure and mechanical properties of Duplex Stainless Steel UNS S31803. Three times welding repair were performed using combination of GTAW and SMAW with average of heat input around 1.5-1.8 kJ/mm. After welding, the test samples were prepared for microhardness test, Charpy impact test, weight loss test in FeCl₃.6H₂O linier polarization test, and SEM/EDS examinations. The results showed that multiple repair welding has no significant effect to the mechanical properties, which indicated by no noticeable increment or reduction of Charpy impact value neither Vickers microhardness between each welding repair. For corrosion point of view, the third repair experienced the significant weight loss and highest reduction of E_pit. Furthermore, the morphology of microstructure and corroded area in weld metal and heat affected zone were also investigated to achieve more understanding regarding the effect of multiple repairs to the properties of Duplex weldment. Bearing in mind that at the moment, carrying out just one repair per welded joint for Duplex Stainless Steel is advised as the limiting condition.

Abstrak :
ABSTRAK
Pengelasan logam yang berbeda atau dikenal dengan istilah dissimilar metal welding adalah pengelasan antara dua logam yang mempunyai komposisi kimia dan sifat mekanik yang berbeda. Pengelasan antara baja karbon dengan baja duplex stainless steel seringkali dilakukan di berbagai industri. Pengelasan ini menjadi proses yang kompleks karena kedua logam yang dilas mempunyai perbedaan komposisi kimia, sifat mekanik, dan sifat termal sehingga selama proses pengelasan menghasilkan sifat mekanis dan perubahan struktur mikro yang mempengaruhi performa sambungan. Dan juga terjadi perubahan struktur mikro di daerah lasan dimana karbon di heat affected zone (HAZ) baja karbon bermigrasi ke melt zone di perbatasan antara base metal dengan logam lasan membentuk chromium carbide yang merupakan daerah keras (hard zone) dalam matriks martensite. Tujuan penelitian ini adalah mengamati pengelasan jenis butt dan fillet serta perubahan struktur mikro dan pengaruhnya terhadap distribusi kekerasan pada pengelasan logam antara baja berkekuatan tinggi HY80 dengan baja tahan karat dupleks 2205. Metode pengelasan menggunakan las busur listrik Shield Metal Arc welding (SMAW) dengan variabel masukan panas dan jenis kawat las E2209. Struktur mikro diobservasi menggunakan mikroskop optik (MO), Scanning Electro Microscope (SEM) dan pengujian sifat mekanik meliputi distribusi kekerasan di daerah base metal (BM), heat affected zone (HAZ) dan weld metal (WM).

---

ABSTRACT
Dissimilar metal welding is welding joint between two metals that have different chemical compositions and mechanical properties. Welding between carbon steel and duplex stainless steel is often done in various industries. This welding is a complex process because the two welded metals have different chemical compositions, mechanical properties, and thermal properties so that during the welding process they produce mechanical properties and microstructure changes that affect the performance of the joints. And there is also a change in microstructure in the weld area where carbon in the carbon steel heat affected zone (HAZ) migrates to the melt zone forming chromium carbide which is the hard zone in the martensite matrix. The purpose of this study was to observe the welding of butt and fillet types and microstructure changes and their effect on the hardness distribution of metal welding differs between HY80 high strength steel and 2205 stainless steel duplex. The welding method uses Shield Metal Arc welding (SMAW) electric arc welding with variable heat input and type of welding wire E2209. Microstructure was observed using optical microscopy, Scanning Electro Microscope and mechanical properties testing including hardness distribution in base metal, heat affected zone, and weld metal regions.

Abstrak :
Penyambungan dua jenis material merupakan salah satu tantangan dalam industri manufaktur. Salah satu aplikasinya dilakukan pada penyambungan antara pipa baja tahan karat Dupleks 2205 disambungkan dengan pelat baja HY80 yang banyak dipakai bahan bakar kapal selam. Pengelasan menggunakan SMAW (Shielded Metal Arc Welding) dilakukan karena merupakan pengelasan yang paling efisien dan baik bagi baja paduan. Setelah proses pengelasan dilakukan pengujian radiografi menggunakan sinar X, pengukuran tegangan sisa dengan hamburan neutron untuk mengukur ketahanan sisa di dalam serta menggunakan hamburan sinar X untuk pengukuran tegangan sisa di permukaan, selanjutnya untuk melengkapi data dilakukan juga pengujian kekerasan material dan pengambilan gambar struktur mikro atau metalografi, serta uji tekuk untuk mengetahui kekuatan hasil lasan. Hasil pengujian menunjukkan bahwa masukan panas yang lebih tinggi selain menghasilkan ukuran butir yang lebih besar, ternyata juga menghasilkan karbida yang lebih banyak sehingga kekerasannya lebih tinggi. Tingginya nilai kekerasan akan memberikan efek terhadap nilai tegangan sisa, kekerasan yang tinggi dihasilkan dari tegangan yang bersifat kompresi, sementara tegangan sisa bersifat tarik akan menghasilkan kekerasan yang rendah.

 

---

Joining two types of material is one of the challenges in the manufacturing industry. One application is carried out on the connection between HY80 steel plates connected with Duplex 2205 stainless steel pipes which are widely used as submarine fuel. Welding using SMAW (Shielded Metal Arc Welding) is done because it is the most efficient and good welding for alloy steel. After the welding process, radiographic testing using X-rays is carried out, the residual stress measured at the surface (using X ray diffraction) and in the middle of the metal (using neutron diffraction), hardness checked, metallography, and buckling test are also done to determine the strength of weld results. The test results show that higher heat input in addition to producing larger grain sizes, it also produces more carbides so that the hardness is higher. The high value of hardness will have an effect on the value of residual stress, high hardness is produced from compressive stress, while the tensile residual stress will produce low hardness.

 

Abstrak :
Perlakuan panas dilakukan untuk membebaskan tegangan pada baja tahan karat dua fasa SAF 2205 hasil pengerjaan dingin. Perlakuan panas dilakukan pada temperatur 350°C, 450°C, 550°C dengan waktu tahan 10 dan 40 menit. Pengujian korosi erosi pada sampel hasil perlakuan panas dengan menggunakan metode slurry pot dalam larutan HCL 0.3 M dan pasir silika (SiO2) dengan mekanisme tumbukan partikel padat dalam kondisi asam dengan pH 0.85. Hasil pengujian menunjukkan bahwa perlakuan panas yang dilakukan pada baja tahan karat dua fasa SAF 2205 menurunkan tingkat ketahanan korosi erosi pada permukaan logam. ......Heat treatment was conducted for stress relieving in duplex stainless steel SAF 2205 as cold worked. The annealing was conducted in temperature of 350°C, 450°C, 550°C with holding time 10 and 40 minutes. Erosion-corrosion testing was conducted on the heat treated samples with slurry pot method in chloride acid 0.3 M solution and silica sand (SiO2) with solid particles impingement mechanism in acid condition with pH 0.85. The results showed that heat treatment can reduce the resistance of erosion-corrosion on the surface of duplex stainless steel SAF 2205.