1- What are the three type of steel making processes? - Open Hearth Process: the heat required to melt the pig iron and scrap is obtained by burning a mixture of gas and air over the metal - the Basic Oxygen Process: A typical basic oxygen furnace consists of a steel cased converter lined with dolomite holding up to 400 tonnes of metal. The charge consists of up to 40% of scrap steel, lime and molten pig iron. - Electric Furnace Process (Electrical Arc Steel Making): The impurities are oxidized from the charge by melting it under a covering of slag which absorbs the oxidized impurities and may then be run off by tilting the furnace. 2- There are different adhesives groups, where dose each group get its properties from? - - Flexible Adhesives: Flexible adhesives are used when some flexing, or slight relative movement of the joint, is essential and where high load-carrying properties are not paramount (In general, flexible adhesives are based on flexible plastics or elastomers, whereas structural adhesives are based on resins, (the most common ones being epoxy or polyester) Structural Adhesives: Structural adhesives are primarily aimed at applications where high loads must be carried without excessive creep. They are, therefore, relatively rigid, but without being excessively hard or brittle. 3- What’s the difference between annealing and normalizing? - Annealing: Annealing is normally achieved on carbon steel by heating to just above the Upper Critical Limit followed by very slow cooling. Normalizing: Normalizing restores the crystalline structure to a normal condition and relieves stresses and strains. Normalizing is carried out by heating the steel slowly to its upper critical point and then allowing it to cool freely in the air. 4- What is elasticity? And what is the opposite of it? - Elasticity: The ability of a metal to return to its original shape and size after the removal of any distorting force. And the opposite is Hardness: The ability of a metal to resist wear and penetration 5- Explain the stages of creep? - Primary Creep - begins at a relatively rapid rate, but then decreases with time as strain-hardening sets in. Secondary Creep - the rate of strain is fairly uniform and at its lowest value. Tertiary Creep - the rate of strain increases rapidly, finally leading to rupture. This final stage coincides with gross necking of the component, prior to failure. The rate of creep is at a maximum in this phase 6- What is the hesitation phase? And why dose it occurs? - Why? due to a change in the crystalline structure of the steel in between the two critical points. 7- What’s the difference between high cycle fatigue and low cycle fatigue? - High cycle fatigue is a type of fatigue caused by small elastic strains under a high number of load cycles before failure occurs. The stress comes from a combination of mean and alternating stresses. - 8- How is toughness of metals tested? - Hardness is the resistance of a material to indentation, and by pressing a suitably shaped indenter into the surface of the material being tested, a comparison of hardness values can be made. The diameter of the impression is then measured using a calibrated microscope. 9- What are the three type of cooling? 10- How is steel or aluminum made to be malleable and ductile? 11- Name three of metal forming methods and provide the following information about it: - Page 114 - Name: Casting Procedure: pouring of molten material into a shaped mold and allowing it to solidify to that shape. Uses: ocean going ships propeller Advantages: high production rates, good surface finish, high quality. Disadvantages: - Name: casting Procedure: Uses: Advantages: Disadvantages: - Name: casting Procedure: Uses: Advantages: Disadvantages: Define thermoplastic materials. - Thermoplastic materials, in their normal state, are hard but become soft and pliable when heated When softened, thermoplastic materials can be molded and shaped, and they retain their new shape when cooled. Unless their heat limit is exceeded, this process can be repeated many times without damaging the material. Define Elastomers: - natural or, synthetic materials (polymers) which have considerable elastic properties Which kind of thermoplastic is not affected by boiling water? - Polypropylene What is a seal ? and which materials are commonly used for manufacturing it? - Seals or packing rings, serve to retain fluids and gases, within their respective systems, as well as to exclude air, moisture and contaminants. - The most common materials, from which seals are manufactured, are natural rubber, synthetic rubber and Teflon Name 2 types of seals and their usage:
