Bahan Konstruksi Industri (TKK-2238)

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1 Bahan Konstruksi Industri (TKK-2238)
15/16 Semester genap Bahan Konstruksi Industri (TKK-2238) Instructor: Rama Oktavian Office Hr.: T , Th ; 13-15, F ; 13-15

2 Bahan Konstruksi The principal construction materials for welded, forged and cast chemical vessels are: cast irons Carbon steel Steel alloy Nickel

3 Bahan Konstruksi Cast iron Properties of cast iron
Because cast iron has a carbon content approximately equivalent to its eutectic composition, it can be cast at lower temperatures than steel and flows more readily than steel because of its much narrower temperature solidification range. Most commercial cast irons contain 2.5-4% carbon About % carbon is in a bound form as cementite (iron carbide)

4 Bahan Konstruksi Cast iron Properties of cast iron
The cast irons do not possess ductility. They cannot be pressed or forged even while heated

5 Bahan Konstruksi Cast iron Properties of cast iron

6 Bahan Konstruksi Gray Cast iron
the most commonly used cast iron and is the least expensive The tensile strength of gray cast iron ranges from 155 to 400 N/mm2 (10 to 26 ton/in.2). The tensile modulus ranges from 70 to 140 kN/mm2 The hardness from 130 to 300 DPN In the British standard BS1452, for example, there are seven grades The recommended maximum design stress in tension is one-quarter the ultimate tensile strength. The fatigue strength is one-half the tensile strength

7 Bahan Konstruksi Gray Cast iron Properties of gray cast iron

8 Bahan Konstruksi White Cast iron
very hard (from 400 to 600 DPN) and brittle. very difficult to machine and usually are finished by grinding

9 Bahan Konstruksi Malleable Cast iron
made by high-temperature heat treatment of white iron castings applied to the fabrication of conveyor chain links , pipe fittings and gears

10 Bahan Konstruksi Nodular Cast iron (ductile cast iron)
manufactured by inoculating the molten metal with magnesium or cesium used for many applications such as valves in pipelines for petroleum products, underground pipelines and so on A wide variety of (25 to 40 tonf/in.*), elongations from 17 to 2%, and hardness from 150 to 300 DPN (see Table 3.1). The tensile modulus is approximately 170 kN/mm2 grades are available, with typical tensile strengths ranging from 380 to 700 N/mmz

11 Bahan Konstruksi Austenitic Cast iron (ductile cast iron)
produced by mixing in nickel from 13-30%, chromium from 1-5% and copper from % The main advantages of austenitic cast irons are corrosion and heat resistance

12 Bahan Konstruksi Application requirement for cast iron
Corrosion resistance Temperature resistance The corrosion resistance of unalloyed and low-alloy flake, nodular, malleable and white cast iron is comparable to mild- and low-alloy steel. However, these cast irons have a major advantage over steel; namely, greater cross section or wall thickness than steel. Consequently, they have

13 Besi dan paduannya 1. Struktur Besi Cor
Gambar 1. Diagram keseimbangan besi-karbon

14 Bahan Konstruksi Steel
obtained an exclusive importance because of their strength, viscosity, and their ability to withstand dynamic loads beneficial for producing castings, forgings, stamping, rolling, welding, machining and heat treatment works Most steels have a carbon content of 0.1-1%, but in structural steels this does not exceed 0.7% carbon steels designed for welding, the carbon content must not exceed 0.3%. in the alloy steels it must not exceed 0.2%

15 Bahan Konstruksi Low-carbon Steel Contains <0.25% carbon
Typical mechanical properties (Grade 43A in BS4360)

16 Bahan Konstruksi Low-carbon Steel Corrosion resistance
suitable for handling organic solvents, with the exception of those that are chlorinated, cold alkaline solutions, sulfuric acid at concentrations greater than 88% and nitric acid at concentrations greater than 65% at ambient temperatures. rapidly corroded by mineral acids (pH <5). Heat resistance The maximum temperature is 550 °C. At temperatures below 10°C the mild steels may lose ductility, causing failure by brittle fracture

17 Bahan Konstruksi High-carbon Steel Low-Carbon, Low-Alloy Steels
Contains >0.3% carbon Tensile strength up to 1000 N/mm2 Low-Carbon, Low-Alloy Steels The carbon content of these steels is usually below 0.2%, and the alloying elements that do not exceed 12%are nickel, chromium, molybdenum, vanadium, boron and copper

18 Bahan Konstruksi The application of low-carbon, low-alloy steels

19 Bahan Konstruksi Mechanical properties of Low-Carbon, Low-Alloy Steels

20 Bahan Konstruksi Low-Carbon, Low-Alloy Steels Corrosion resistance
The addition of 0.5% copper forms a rust-colored film preventing further steel deterioration. small amounts of chromium (1%) and nickel (0.5%) increase the rust resistance

21 Bahan Konstruksi Low-Carbon, Low-Alloy Steels Corrosion resistance
Small additions of molybdenum prevent hydrogen attack at temperatures up to 350°C and pressures up to 56 kgf/cm2

22 Bahan Konstruksi Low-Carbon, Low-Alloy Steels Oxidation resistance
Chromium is the most effective alloying element for promoting resistance to oxidation

23 Penggunaan besi baja yg paling utama adl : konstruksi baja yg memerlukan keuletan yg tinggi pada temp kamar atau lebih rendah. Karbon adl unsur yg paling utama untuk menguatkan baja,harus ada karbon sampai kadar tertentu. Tetapi kadar karbon yg meningkat dapat meningkatkan temperatur transisi(yg diharapkan selalu lebih rendah) Kalau dilihat mudah / tidaknya untuk di las, kadar karbon harus dikontrol sampai batas tertentu. Ir. Ignatius Gunardi, MT. Teknik Kimia ITS

24 Mn mengurangi karbida dan menurunkan temperatur transformasi
Mn mengurangi karbida dan menurunkan temperatur transformasi. Perbandingan Mn/C tinggi memperbaiki keuletan pada temperatur rendah P memperburuk kegetasan pada temperatur rendah dan meningkatkan sesitivitas dari kegetasan, oleh karenanya P harus selalu minimum. S adl unsur yg membentuk inklusi dan tidak memberikan banyak pengaruh thd temperatur transisi,tetapi menurunkan keuletan Ir. Ignatius Gunardi, MT. Teknik Kimia ITS

25 Study yg banyak dipelajari:
Ni bersama Mn adl unsur yg sangat effektif untuk memperbaiki keuletan pd temp rendah. Study yg banyak dipelajari: Komposisi dasar Ni: 1,5%Ni, 3,5%Ni, 6 %Ni, 9%Ni. Mo adl unsur yg paling effektif untuk mengendalikan kegetasan N meningkatkan sensitivitas thd pengerasan. Seharusnya N rendah, karena menyebabkan kegetasan. Ir. Ignatius Gunardi, MT. Teknik Kimia ITS

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31 Thank You !