BAJA PADUAN DAN SUPER ALLOY Dr.-Ing. Bambang Suharno Dr. Ir. Sri Harjanto 1. 2. 3.
ALASAN PENGGUNAAN KLASIFIKASI PENGGUNAAN
Department of Metallurgy and Materials University of Indonesia 2008
University of Indonesia
Silabus Tujuan : Memahami berbagai jenis material baja paduan dan super Alloy serta penggunaannya dalam bidang rekayasa Evaluasi:
UTS = 35 % UAS = 45 % Tugas = 20 % Lain-lain = 5 %
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Silabus
Penggunaan Baja Paduan dan Super Alloy Pengaruh Unsur Paduan Stainless Steel (Baja Tahan Karat) Heat Resistant Steel Wear/ Abrassion Resistant Steel Tool Steel Super Alloy Ni based, Co based
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
BAJA KARBON Low-carbon < 0.30% C. Flat-rolled products (sheet or strip), usually in the coldrolled and annealed condition. The carbon content for these high-formability steels is very low, less than 0.10% C Typical uses are in automobile body panels, tin plate, and wire products. For rolled steel structural plates and sections, the carbon content may be increased to approximately 0.30%, with higher manganese content up to 1.5%. These materials may be used for stampings, forgings, seamless tubes, and boiler plate.
Department of Metallurgy and Materials University of Indonesia
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Steel Making Flowlines University of Indonesia
Department of Metallurgy and Materials University of Indonesia
Steel Making Flowlines University of Indonesia
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
BAJA KARBON Medium-carbon steels carbon ranges from 0.30 to 0.60% and the manganese from 0.60 to 1.65%. Medium carbon steels to be used in the quenched and tempered condition. The uses of medium carbon-manganese steels include shafts, axles, gears, crankshafts, couplings and forgings. Steels in the 0.40 to 0.60% C range are also used for rails, railway wheels and rail axles.
High-carbon steels 0.60 to 1.00% C with manganese from 0.30 to 0.90%. used for spring materials and high-strength wires.
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
Pengaruh Karbon Pada Baja
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Fe-Fe3C
0.5% C ferrite + pearlite
1.5% C ferrite + cementite 0.5%C
0.8%C 1.5%C
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
WHY WE NEED ALLOYS? Keterbatasan Baja Karbon: a) b) c)
d)
A high critical cooling rate which leads to cracking when quenching hardening. Poor Hardenability. Ultimate Tensile Strength rendah Jika di Heat Treatment → Elongasi Rendah Toughness Rendah Ketahahan Korosi (Corrosion Resistant) Rendah Ketahanan Aus (Wear Resistant) Rendah Ketahanan Panas (Heat Resistant) Rendah
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
KLASIFIKASI BAJA
Definisi Baja : Material berbahan dasar Fe, dengan C maks : 2% Kadar C boleh ≥ 2% → Tetapi harus ada unsur lain (paduan) Serta mengandung unsur pengikut seperti Si, P, S, Mn dan unsur paduan seperti Cr,Ni, Mo, V, W dll.
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
KLASIFIKASI BAJA Klasifikasi Baja dapat berdasarkan: The composition, such as carbon, low-alloy or stainless steel. The manufacturing methods, such as open hearth, basic oxygen process, or electric furnace methods. The finishing method, such as hot rolling or cold rolling The product form, such as bar plate, sheet, strip, tubing or structural shape The deoxidation practice, such as killed, semi-killed, capped or rimmed steel The microstructure, such as ferritic, pearlitic and martensitic The required strength level, as specified in ASTM standards The heat treatment, such as annealing, quenching and tempering, and thermomechanical processing Quality descriptors, such as forging quality and commercial quality.
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
Penggunaan Baja Paduan Industry Minyak, Gas dan Petrokimia : Corrosion Resistant and Heat Resistant Steel SS 304, 316, 309, 310 Industri Semen dan Pertambangan: Wear Resistant Steel (Keras dan Tangguh) Ni Hard, High C-Chrom Steel, Baja Mn Industri Manufacture Tool Steel (H13 = SKD61, P20)
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Super Alloys Adalah paduan yang dikembangkan untuk penggunaan material pada temperatur tinggi, tahan hot corrosion and errosion Semula dikembangkan untuk aircraft turbine engine Umumnya mengandung Fe, Ni, Co, Cr dan sejumlah W, Mo, Ta,Nb, Ti dan Al. Contoh Hastealloy, Inconel
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
Elemen Paduan
Terdiri atas : Carbide Former. Austenite Stabilizer. Ferrite Stabilizer. Graphitizer.
Secara Umum 1. Penstabil γ → memperlebar daerah γ 2. Penstabil α → memperlebar daerah α Seluruh paduan, kecuali Co : 1. Menurunkan Ms dan Mf 2. Mendorong kurva TTT ke kanan → memperlambat pembentukan Perlit / Bainit
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Pengaruh Elemen Paduan Terhadap Diagram Time Temp Transformation
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
Carbide Former (Pembentuk Karbida)
Beberapa elemen paduan membentuk karbida stabil yang lebih keras dari iron carbides (Fe3C) Dapat meningkatkan kekerasan (hardness) → cocok untuk keperluan tool (perkakas), tahan panas Cr, Mn, Nb, Mo, Ti, W, V.
Department of Metallurgy and Materials University of Indonesia
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Austenite Stabilisers
University of Indonesia
C, Co, Cu, Ni, Mn, N meningkatkan A4 Temp (austenine-delta) menurunkan A3 Temp Jika elemen tersebut ditambahkan pada C-Steel akan menstabilkan fasa γ. Elemen paduan ini tidak membentuk carbida, C tetap tinggal dalam “solid solution” dalam γ. Bahkan jika paduan jumlahnya banyak pada temperatur kamar tetap berfasa γ (non magnetis) misal : Austenitik Stainless Steel
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
Mn Sebagai Austenite Stabilizer
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Fe-C Diagram
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
Ferrite Stabilisers Al, Cr, Si, Mo, Nb, Ta, Ti, W, V, Zr Jika ditambahkan dalam baja menstabilkan fasa Ferit (alpha) Pada Temperatur kamar, berfasa Ferit Struktur kristasl BCC (Body Centered Cubic) Contoh: Ferritic Stainless Steel
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Cr Sebagai Ferrite Stabilizer
Department of Metallurgy and Materials University of Indonesia
University of Indonesia
Mo Sebagai Ferrite Stabilizer
Department of Metallurgy and Materials University of Indonesia
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University of Indonesia
Graphitisers
Tak semua elemen paduan berkombinasi dengan C (Ni, Al, Si), sehingga C cenderung sebagai “free graphite”. Jika unsur tersebut harus ada, maka: Perlu adanya elemen paduan pembentuk karbida, atau kandungan C dibuat “very low”. Karenanya tak mungkin membuat high C-high Ni alloy steel.
Department of Metallurgy and Materials University of Indonesia
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