ALLOY STEELllllllllllllllllllllllllllllllllllllllll.pptx

sdfsdfsdfsdff

1. ALLOY STEEL سليمان يونس سليمان

2. CLASSIFICATION OF MATERIALS

3. Metals form about a quarter of the earth crust by weight. Some of the earliest metals used include: copper, bronze and iron All metals except gold are generally found chemically combined with other elements in the form of oxides and sulphates . Commonly known as ores. Metals are derived from ores by removing the impurities. Those are used for engineering purpose are classified as ferrous (iron as the major constituent) and Non-ferrous .

4. In The Basis Of Carbon Content Steel Are Classified Type of steel Carbon content Dead mild steel < 0.15% Mild steel 0.15-0.3% Medium carbon steel 0.3-0.8 % High carbon steel 0.8-1.5% Hard steel >1%(also called as cast steel )

5. LOW CARBON STEEL 6 Also known as mild steel Contain 0.15% -0.32% carbon Tough, ductile and malleable Easily joined and welded Poor resistance to corrosion Often used a general purpose material, Nails, screws, car bodies, It is also used in the form of rolled sections ,reinforcing bars, roof coverings etc.

6. Medium Carbon Steel Carbon content in the range of 0.3 – 0.6%. Can be heat treated - austenitizing, quenching and then tempering. Medium carbon steels have low hardenability . Addition of Cr, Ni, Mo improves the heat treating capacity . Heat treated alloys are stronger but have lower ductility . Typical applications – Railway wheels and tracks, gears, crankshafts.

7. High Carbon Steel 8 Also known as ‘tool steel’ Contain 0.55%-1.5% carbon Very hard but offers Higher Strength Less ductile and less malleable. Hand tools (chisels, punches),Saw blades.

8. ALLOY STEEL Alloys are mixtures of two or more metals formed together with other elements/materials to create new metals with improved Mechanical Properties and other properties of the base metal. In general the properties desired in a metal to be used as building material are not present advantage in any single metal. To develop specific properties a combination of metals or metallic substances is done and are classified as alloys. The aim of making alloy is generally to make them less brittle, resistant to corrosion or to have a more desirable color and luster. Alloy steels are broken down into two groups: low-alloy steels and high-alloy steels. Most commonly, the phrase "alloy steel" refers to low-alloy steels

9. High-Strength Low-Alloy Steels High-strength low-alloy (HSLA) steels, or microalloyed steels, are designed to provide better mechanical properties and/or greater resistance to atmospheric corrosion than conventional carbon steels. are designed to meet specific mechanical properties rather than a chemical composition. The HSLA steels have low carbon contents (0.05-0.25% C) in order to produce adequate formability and weldability, and they have manganese contents up to 2.0%. Small quantities of chromium, nickel, molybdenum, copper, nitrogen, vanadium, niobium, titanium and zirconium are used in various combinations.

10. Low-alloy Steels Low-alloy steels constitute a category of ferrous materials that exhibit mechanical properties superior to plain carbon steels as the result of additions of alloying elements such as nickel, chromium, and molybdenum. Total alloy content can range from 2.07% up to levels just below that of stainless steels, which contain a minimum of 10%  Cr . For many low-alloy steels, the primary function of the alloying elements is to increase hardenability in order to optimize mechanical properties and toughness after heat treatment. In some cases, however, alloy additions are used to reduce environmental degradation under certain specified service conditions. .

11. USES OF ALLOYS Over 90% of metal use is in the form of alloys. Alloys are used because their chemical and physical properties are superior for an application than that of the pure element components. Typical improvements include corrosion resistance, improved wear, special electrical or magnetic properties, and heat resistance. Other times, alloys are used because they retain the key properties of component metals, yet are less expensive.

12. Alloy steels and composition Sl no. Alloy steel Composition 1 Stainless steel Chromium(10-20%) 2 Nickel steel Nickel(3.5%) 3 Invar steel Nickel (30-40%) 4 Vanadium steel Vanadium(0.1-2%) 5 Tungsten steel Tungsten(14-20%) 6 Manganese steel Manganese (12-15%) 7 Molybdenum steel Molybdenum (0.2-0.3%)

13. Stainless steel Stainless steels generally contain between 10-20% chromium as the main alloying element. are valued for high corrosion resistance. With over 11% chromium, steel is about 200 times more resistant to corrosion than mild steel. They are very hard and tough, high elastic and ultimate strength, acid and rust proof. These steels can be divided into three groups based on their crystalline structure: Austenitic: Austenitic steels are non-magnetic and non heat-treatable, and generally contain 18% chromium, 8% nickel and less than 0.8% carbon. Austenitic steels form the largest portion of the global stainless steel market and are often used in food processing equipment, kitchen utensils, and piping. Ferritic: Ferritic steels contain trace amounts of nickel, 12-17% chromium, less than 0.1% carbon, along with other alloying elements, such as molybdenum, aluminum or titanium. These magnetic steels cannot be hardened by heat treatment but can be strengthened by cold working. Martensitic: Martensitic steels contain 11-17% chromium, less than 0.4% nickel, and up to 1.2% carbon. These magnetic and heat-treatable steels are used in knives, cutting tools, as well as dental and surgical equipment.

14. USES Ball bearings Dies Crushing machine Kitchen utensils

15. Nickel steel Composition-(Nickel 3.5%) Capabilities. Nickel alloys are readily welded by either the gas or arc methods. It can be machined, forged, cast, and easily formed. Properties More elastic Higher tensile strength Lesser brittle than mild steel Improved hardness and ductility Limitations. Nickel cannot withstand heat above 600° Fahrenheit. It oxidizes very slowly in the presence of moisture or corrosive gases. The nickel steel alloy has more corrosion as compared to steel. The use of nickel increases corrosion in steel

16. EFFECT OF ALLOYING NICKEL TO STEEL Effect on Toughness ( ) When   nickel is added to steel as an alloy, the nickel component increases the toughness of steel. Due to the increase in toughness, the property of steel to resist fracture due to high impact increases. This property is beneficial in parts made of steel subjected to shock and impact load. Effect on distortion ( ) The addition of nickel in steel decreases the value of distortion (distortion energy) at the time of quenching. Effect on Critical Temperature ( ) T he critical temperature of steel decreases when nickel is added to it. Due to decrease in critical temperature, steel becomes better for any type of  heat treatment. Effect on Strength ( ) The strength of steel increases because of alloying nickel in the steel. Effect on Abrasive Resistance ( ) The abrasive resistance of steel increases when nickel is added to it as an alloy. Effect on Elastic Limit ( ) Nickel increases the elastic limit of steel.

17. Uses of Nickel Steel Alloy Nickel steel alloy is used for making storage cylinders for liquefied gases and for other low temperature applications. Nickel steel alloy is used for heavy forgings, turbine blades, highly stressed screws, bolts, and nuts. It is used for making shafts, gears, propeller shafts, and keys. Automobile and airplane parts. It is widely used in combination with chromium and molybdenum for cams, chain pins, springs, connecting rods and their bolts, crankshafts, rolling element, and bearings.