CE 1205 CONSTRUCTION MATERIALS WEEK 2 Chapter 2

CE 1205 CONSTRUCTION MATERIALS WEEK 2 Chapter 2 (Part 1/2) Mechanical Properties of Metals Power. Point® Slides by Salmaliza Salleh Last Updated: 2/13/2018 © LMS SEGi education group 1

GUGGENHEIM MUSEUM IN BILBAO, NEW YORK (material: Titanium) Last Updated: 2/13/2018 © LMS SEGi education group 2

CHAPTER OVERVIEW • Chapter 2 exposed you with the different types of metal and alloy and how they were processed. • You learned about how do metals respond to external loads. • You also learned to draw and interpret stress-strain diagram. Last Updated: 2/13/2018 © LMS SEGi education group 3

LEARNING OBJECTIVES • To expose the students with the processing of metal and alloy and stresses and strains in metals. Last Updated: 2/13/2018 © LMS SEGi education group 4

LEARNING OUTCOMES • At the end of the class, students must be able to describe the processing of metal and alloy and define stresses and strains in metals. Last Updated: 2/13/2018 © LMS SEGi education group 5

METAL VS ALLOY • Metallic element: any of several chemical elements that are usually shiny solids that conduct heat or electricity. • Alloy: a mixture containing two or more metallic elements or metallic and nonmetallic elements usually fused together or dissolving into each other when molten; e. g. "brass is an alloy of zinc and copper" Last Updated: 2/13/2018 © LMS SEGi education group 6

EXAMPLES • Zirconium A gray strong metallic element, used in nuclear reactors as a neutron absorber • • Niobium Soft gray ductile metallic element, temperature stabled, • used for gas pipelines, jet engines and rocket engines • Titanium a light-weight, strong gray corrosion-resistant metallic element, used for airplane parts • • Steel • an alloy of iron with small amounts of carbon; widely used in construction; mechanical properties can be varied over a wide range Last Updated: 2/13/2018 © LMS SEGi education group 7

EXAMPLES • Brass is any alloy of copper and zinc • • • Bright gold-like appearance Applications: • musical instruments such as the trumpet, saxophone • fan blades, locks, doorknobs, zippers Bronze is principally an alloy of copper and tin • Oxidizes only minimally Resists corrosion (especially seawater corrosion) Resists metal fatigue Good electrical conductor • Low coefficient of friction. • • • Last Updated: 2/13/2018 © LMS SEGi education group 8

GENERAL METALWORKING PROCESSES Material Process Iron Steel Aluminium Copper Magnesium Nickel Sand casting x x x o Permanent mold casting x o x o o x Die casting Refractory metals Titanium Zinc x Investment casting x x x o o Closed-die forging x o o o Extrusion o x x x o o o Cold heading x x x Stamping & deep drawing x x x o x o Screw machine o x x x Powder metallurgy x x o o o o o x o Key: X = Routinely performed, 0 = Performed with difficultly, caution, or some sacrifice, blank = Not recommended Last Updated: 2/13/2018 © LMS SEGi education group 9

CATEGORIES OF METALWORKING 1. Forming 2. Cutting 3. Joining www. freepatentsonline. com/6820451. html Last Updated: 2/13/2018 © LMS SEGi education group 10

1. FORMING PROCESSES • These processes modify the shape of the object being formed by deforming the object, that is, without removing any material; • heating until molten, poured into a mold, and cooled, • heating until the metal becomes plastically deformable by application of mechanical force, • by the simple application of mechanical force. Last Updated: 2/13/2018 © LMS SEGi education group 11

2. CUTTING • is a collection of processes wherein material is brought to a specified geometry by removing excess material using various kinds of tooling to leave a finished part that meet specifications. • The net result of cutting is two products, the waste or excess material, and the finished part. Last Updated: 2/13/2018 © LMS SEGi education group 12

TECHNOLOGIES OF CUTTING METAL • There are many technologies available to cut metal, including: • • Last Updated: 2/13/2018 Manual technologies: saw, chisel, shear or snips Machine technologies: turning, milling, drilling, grinding, sawing Welding/burning technologies: burning by laser, oxy-fuel burning, and plasma Erosion technologies: by water jet or electric discharge. © LMS SEGi education group 13

EXAMPLES OF CUTTING WORKS CHISEL when cutting sheet metal OXY-FUEL BURNING SNIP MILL can perform a vast number of complex operations, such as slot cutting, drilling and threading SHEAR Last Updated: 2/13/2018 © LMS SEGi education group 14

3. JOINING Ø Welding: done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint. Ø Soldering is a joining process that occurs at temperatures below 449 Celsius. Because of this lower temperature and different alloys used as fillers, the metallurgical reaction between filler and work piece is minimal, resulting in a weaker joint. Ø Brazing is similar to soldering, but occurs at temperatures in excess of 450 degrees Celsius Last Updated: 2/13/2018 © LMS SEGi education group 15

EXAMPLES OF JOINING WORKS Soldering Circuit Board Fillet Weld Butt Welded Joints Last Updated: 2/13/2018 © LMS SEGi education group 16

HOW DO METALS RESPOND TO EXTERNAL LOADS? • Stress and Strain • • Tension Compression Shear Torsion • Elastic deformation • • • Plastic Deformation • • Last Updated: 2/13/2018 Young’s Modulus Poisson Ratio © LMS SEGi education group Yield Strength Tensile Strength Ductility Hardness 17

INTRODUCTION To understand describe how materials deform (elongate, compress, twist) or break as a function of applied load, time, temperature, we need first to discuss standard language for mechanical properties of materials. Last Updated: 2/13/2018 © LMS SEGi education group 18

STRESS • Stress is a measure of the average amount of force exerted per unit area. • It is a measure of the intensity of the total internal forces acting within a body across imaginary internal surfaces, as a reaction to external applied forces and body forces. • The unit is Pascal (Pa) or Newton per metre square (N/m 2) or kg / ms² Last Updated: 2/13/2018 © LMS SEGi education group 19

STRAIN • Strain is the geometrical measure of deformation representing the relative displacement between particles in the material body, i. e. a measure of how much a given displacement differs locally from a rigid-body displacement. (Jaboc Lubliner). • The deformation of a physical body under the action of applied forces. • Strain is a dimensionless quantity, which can be expressed as a decimal fraction, a percentage or in parts -per notation. Last Updated: 2/13/2018 © LMS SEGi education group 20

STRAIN (continue) • normal strain : Strain that defines the amount of stretch or compression along a material line elements or fibers • If there is an increase in length of the material line, the normal strain is called tensile strain, • otherwise, if there is reduction or compression in the length of the material line, it is called compressive strain. • shear strain: the amount of distortion associated with the sliding of plane layers over each other within a deforming body. Last Updated: 2/13/2018 © LMS SEGi education group 21

TENSILE AND COMPRESSION • Tensile stress • • Force per unit crosssectional area applied to elongate a material without tearing apart or rupturing. TENSILE Compression • • compaction: an increase in the density of something applying pressure Last Updated: 2/13/2018 © LMS SEGi education group COMPRESSION 22

SHEAR AND TORSION • • • SHEAR Shear Force • TORSION a force that tends to make two masses of materials slide past each other That type of force that causes or tends to cause two contiguous parts of the same body to slide relative to each other in a direction parallel to their plane of contact TORSION Torsion • a twisting force Last Updated: 2/13/2018 © LMS SEGi education group 23

ANY QUESTIONS? Picture retrieved from http: //www. flickr. com/photos/sputnik 47110815/2513001073/ Last Updated: 2/13/2018 © LMS SEGi education group 24

REFERENCES • Smith W. F. (1993). Foundations of Materials Science and Engineering, 2 nd edition, Mc. Graw-Hill International Edition • Neville, A. M. (1995). Properties of Concrete, 4 th edition. , Addison Wesley Longman Limited, England • John, V. B. (1992) Introduction to Engineering Materials, 3 rd edition, Mc. Millan Press Ltd. • Everett, A. (1996). Materials, 3 rd edition Addison Wesley Longman Limited, England Last Updated: 2/13/2018 © LMS SEGi education group 25