INDUSTRIAL MATERIALS

1. INDUSTRIAL MATERIALS Instructed by: Dr. SajidZaidi PhD in Advanced Mechanics, UTC, France MS in Advanced Mechanics, UTC, France B.Sc. in Mechanical Engineering, UET, Lahore B.TECH Mechanical Technology IQRA COLLEGE OF TECHNOLOGY (ICT) INTERNATIONAL ISLAMIC UNIVERSITY, ISLAMABAD

2. Classification of Ferrous Alloys • Plain Carbon Steel • Plain Carbon steel contains up to 2.14% of Carbon • These steels may also contain other elements, such as Si (maximum 0.6%), copper (up to 0.6%), and Mn (up to 1.65%). • Alloy Steel • Alloy steels are compositions that contain more significant levels of alloying elements. • Cast Iron • Cast Iron contains 2.14 % to 6.70 % of Carbon. INDUSTRIAL MATERIALS Ferrous Alloys

3. Classification of Ferrous Alloys INDUSTRIAL MATERIALS Ferrous Alloys Steel Cast Iron

4. Plain Carbon Steel • Decarburized steels contain less than 0.005% C. • Ultra-low carbon steels contain a maximum of 0.03% carbon. They also contain very low levels of other elements such as Si and Mn. • Low-carbon steels contain 0.04 to 0.15% carbon. These are used for making car bodies and hundreds of other applications. • Mild steel contains 0.15 to 0.3% carbon. This steel is used in buildings, bridges, piping, etc. • Medium-carbon steels contain 0.3 to 0.6% carbon. These are used in making machinery, tractors, mining equipment, etc. • High-carbon steels contain above 0.6% carbon. These are used in making springs, railroad car wheels, etc. INDUSTRIAL MATERIALS Ferrous Alloys

5. Plain Carbon Steel • Steel can be defined as an Iron alloy which transforms to Austenite on heating. • A plain-carbon steels has no other major alloying element beside carbon. • When a plain-carbon steel is slowly cooled from the Austenitic range it undergoes the eutectoid transformation. INDUSTRIAL MATERIALS Ferrous Alloys

6. Alloy Steel • Alloy steels are compositions that contain more significant levels of alloying elements. • Alloying elements are added to steels • To provide solid-solution strengthening of ferrite, • To cause the precipitation of alloy carbides rather than that of Fe3C, • To improve corrosion resistance and other special characteristics of the steel, and • To improve hardenability. • The AISI defines alloy steels as steels that exceed in one or more of these elements: ≥ 1.65% Mn, 0.6% Si, 0.6% Cu. • The total carbon content is up to 1% and the total alloying elements content is below 5%. INDUSTRIAL MATERIALS Ferrous Alloys

7. Alloy Steel • A material is also an alloy steel if a definite concentration of alloying elements, such as Ni, Cr, Mo, Ti, etc., is specified. • These steels are used for making tools (hammers, chisels, etc.) and also in making parts such as axles, shafts, and gears. These are used in making springs, railroad car wheels, etc. • Silicon, chromium, molybdenum, and vanadium are ferrite stabilizing elements whereas manganese and nickel are austenite stabilizers. • Certain specialty steels may consist of higher levels of sulfur (>0.1%) or lead (0.15–0.35%) to provide machinability. These, however, can not be welded easily. • Recently, researchers have developed ‘‘green steel’’ in which lead, an environmental toxin, was replaced with tin (Sn) and/or antimony (Sb). INDUSTRIAL MATERIALS Ferrous Alloys

8. Alloy Steel - Stainless Steel • Stainless steels are selected for their excellent resistance to corrosion. • All true stainless steels contain a minimum of about 11% Cr, which permits a thin, protective surface layer of chromium oxide to form when the steel is exposed to oxygen. • The chromium is what makes stainless steels stainless. • Chromium is also a ferrite stabilizing element. It causes the austenite region to shrink, while the ferrite region increases in size. • For high-chromium, low-carbon compositions, ferrite is present as a single phase up to the solidus temperature. • There are several categories of stainless steels based on crystal structure and strengthening mechanism. INDUSTRIAL MATERIALS Ferrous Alloys

9. Cast Iron • Cast irons are iron-carbon-silicon alloys, typically containing 2.14 to 4% C and 0.5–3% Si. • They pass through the eutectic reaction during solidification. • In cast irons, silicon is the catalyzing agent that allows free carbon (graphite) to appear in the microstructure by breaking down the cementide to iron and carbon. • Silicon, therefore, is a graphite stabilizing element. Gray cast iron • It contains small, interconnected graphite flakes that cause low strength and ductility. This is the most widely used cast iron and is named for the dull gray color of the fractured surface. • Higher strengths are obtained by reducing the carbon equivalent, by alloying, or by heat treatment. INDUSTRIAL MATERIALS Ferrous Alloys

10. Cast Iron • Gray iron has a number of attractive properties, including high compressive strength, good machinability, good resistance to sliding wear, good resistance to thermal fatigue, good thermal conductivity, and good vibration damping. White cast iron • It is a hard, brittle alloy containing massive amounts of Fe3C. • A fractured surface of this material appears white. • A group of highly alloyed white irons are used for their hardness and resistance to abrasive wear. • Elements such as chromium, nickel, and molybdenum are added. Malleable cast iron • It is formed by the heat treatment of white cast iron, produces rounded clumps of graphite. INDUSTRIAL MATERIALS Ferrous Alloys

11. Cast Iron • It exhibits better ductility than gray or white cast irons. It is • also very machinable. • It is produced by heat treating unalloyed 3% carbon equivalent (2.5% C, 1.5% Si) white iron. Ductile (or nodular) cast iron • Ductile iron is produced by treating liquid iron with a carbon equivalent of near 4.3% with magnesium. • Compared with gray iron, ductile cast iron has excellent strength and ductility. • Due to the higher silicon content (typically around 2.4%) in ductile irons compared with 1.5% Si in malleable irons, the ductile irons are stronger but not as tough as malleable • irons. INDUSTRIAL MATERIALS Ferrous Alloys

12. Non-Ferrous Alloys • Nonferrous alloys (i.e., alloys of elements other than iron) include, but are not limited to, alloys based on aluminum, copper, nickel, cobalt, zinc, precious metals (such as Pt, Au, Ag, Pd), and other metals (e.g., Nb, Ta, W). Comparison of Steel and some non-ferrousmetals INDUSTRIAL MATERIALS Non-Ferrous Alloys

13. Aluminum Alloys General Properties and Uses of Aluminium • Aluminum has a density of 2.70 g/cm3, or one-third the density of steel, and a modulus of elasticity of 69 103 MPa. • Aluminum alloys have lower tensile properties compared with those of steel, their specific strength (or strength-to-weight ratio) is excellent. • Aluminum can be formed easily, it has high thermal and electrical conductivity, and does not show a ductile-to-brittle transition at low temperatures. • It is nontoxic and can be recycled easily. • Aluminum’s beneficial physical properties include nonmagnetic behavior and its resistance to oxidation and corrosion. • Aluminum does not display a true endurance limit, so failure by fatigue eventually may occur, even at low stresses. INDUSTRIAL MATERIALS Non-Ferrous Alloys

14. Aluminum Alloys General Properties and Uses of Aluminium • Because of its low-melting temperature, aluminum does not perform well at elevated temperatures. • Finally, aluminum alloys have low hardness, leading to poor wear resistance. • Aluminum responds readily to strengthening mechanisms. INDUSTRIAL MATERIALS Non-Ferrous Alloys

15. Aluminum Alloys General Properties and Uses of Aluminium • About 25% of the aluminum produced today is used in the transportation industry, another 25% is used for the manufacture of beverage cans and other packaging, about 15% is used in construction, 15% in electrical applications, and 20% in other applications. • About 200 pounds of aluminum was used in an average car made in the United States in 1996. • Aluminum reacts with oxygen, even at room temperature, to produce an extremely thin aluminum-oxide layer that protects the underlying metal from many corrosive environments. INDUSTRIAL MATERIALS Non-Ferrous Alloys

16. Aluminum Alloys • Aluminum alloys can be divided into two major groups: wrought and casting alloys, depending on their method of fabrication. • Wrought alloys, which are shaped by plastic deformation, have compositions and microstructures significantly different from casting alloys. • Within each major group we can divide the alloys into two subgroups: heat treatable and non-heat treatable alloys. • Casting Alloys contain enough silicon to cause the eutectic reaction, giving the alloys low melting points, good fluidity, and good castability. Fluidity is the ability of the liquid metal to flow through a mold without prematurely solidifying, and castability refers to the ease with which a good casting can be made from the alloy. INDUSTRIAL MATERIALS Non-Ferrous Alloys

17. Aluminum Alloys INDUSTRIAL MATERIALS Non-Ferrous Alloys

18. Copper Alloys • Copper occurs in nature as sulfides and also as elemental copper. • Copper was extracted successfully from rock long before iron, since the relatively lower temperatures required for copper extraction could be achieved more easily. • Copper is typically produced by a pyro-metallurgical (high-temperature) process. • The copper ore containing high-sulfur contents is concentrated, then converted into a molten immiscible liquid containing copper sulfide-iron sulfide and is known as a copper matte. This is done in a flash smelter. • In a separate reactor, known as a copper converter, oxygen introduced to the matte converts the iron sulfide to iron oxide and the copper sulfide to an impure copper called blister copper, which is then purified electrolytically. INDUSTRIAL MATERIALS Non-Ferrous Alloys

19. Copper Alloys • Copper-based alloys have higher densities than that for steels. Although the yield strength of some alloys is high, their specific strength is typically less than that of aluminum or magnesium alloys. • These alloys have better resistance to fatigue, creep, and wear than the lightweight aluminum and magnesium alloys. • Many of these alloys have excellent ductility, corrosion resistance, electrical and thermal conductivity, and most can easily be joined or fabricated into useful shapes. • Applications for copper-based alloys include electrical components (such as wire), pumps, valves, and plumbing parts, where these properties are used to advantage. • Copper alloys are also unusual in that they may be selected to produce an appropriate decorative color. Pure copper is red; zinc additions produce a yellow color, and nickel produces a silver color. INDUSTRIAL MATERIALS Non-Ferrous Alloys

20. Copper Alloys • Copper containing less than 0.1% impurities is used for electrical and microelectronics applications. Small amounts of cadmium, silver, and Al2O3 improve their hardness without significantly impairing conductivity. INDUSTRIAL MATERIALS Non-Ferrous Alloys