ABSTRAK
Baja tahan karat austenitik adalah material logam yang sangat banyakdigunakan untuk alat-alat industri dan alat-alat transportasi, karena memiliki sifatmekanik dan sifat fisik serta ketahanan terhadap korosi yang baik. Dalam masalahini telah dilakukan penelitian tentang penjelasan plat baja tahan karat austenitiktipe 304 dengan metode GTAW (Gas Tungsten Arc Welding) dan SMAW (ShieldMetal Arc Welding) untuk menganalisa tentang aspek kekuatan mekanik sertapengaruh terhadap presipitasi carbida. Guna mengetahui faktor yang berpengaruhterhadap hasil lasan, maka dibuat variabel arus yaitu 125 A, 110 A, 105A dan 95Adengan media pendingin udara dan air. Dari hasil percobaan ini dilakukan ujimetalografi, uji tarik, uji kekerasan. Pada uji mikro struktur di daerah deposit las,sampel no. 4 memperlihatkan butiran besar yang tidak kontinyu sedangkan padasampel no. 7 terdapat porositi. Dari uji tarik diperoleh hasil, kedua sampeltersebut putus pada daerah las-lasan dengan nilai kekerasan paling tinggi yaitu172 Hv dan 168 Hv. Laju pendinginan mempengaruhi proses terjadinya presipitasicarbida. Makin lambat waktu pendinginan semakin banyak jumlah presipitasicarbida yang terjadi, seperti ditunjukkan pads spesimen GT 105/12, GT 125/12dan SM 110/23. Dari photo mikro diperoleh perbedaan bahwa presipitasi carbidapada batas butir dengan pendinginan udara lebih tampak hitam dibandingkandengan pendinginan air. Lebar pita daerah yang meugalami presipitasi tergantungpada input panas yang diberikan.
Abstract
The austenitic corrosive resistive steel is a metallic material usedextensively in industrial and transportational equipments, it is said so due to theyhave both good mechanical and physical properties as well as their good corrosiveresistive resistance. In this case, there had been done such a welding of anaustenitic resistive steel plate type 304 using both methods such as GTAW (GasTungsten Arc Welding) to analyze the aspect of its mechanical strength and itseffect towards carbide?s precipitation To recognize its factor which effects theresult of welding, so there had been created many different variables of electricalcurrent such as 125 A, 110 A, 105 A and 95 A using both coolingmedias such asair and water. From this experimental result there had been done such ametallographic testing for both tensile testing and testing of its strength. For itsstructural micro testing on the site of welding?s deposit, a no. 4 sample shownsuch a big uncontinued granule, and for a no. 7 sample there are porosities. Fromtheir tensile testing shown such many broken weldings with its highest strength of172 Hv and 168 Hv respectively for its progressiveness of cooling which effectthe process of carbide?s precipitative creation, shown that, the length of time?scooling could determine, the number of carbide?s precipitation to be created, suchhad been shown by the speciments of GT 105/12, GT 125/12 and SM 110/123.From the micro photo there had been obtained, that there had been shown such adifferent carbide?s precipitation, darker for a gzanule?s threshold with a more aircooling compared to the water cooling. For the wideness of band, it is depend onthe heat input to be given. |
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