BioEng 498 lecture 6

BioEng 498 lecture 6 - Metals II: Processing &...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Metals II: Lecture 6 February 5, 2009
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background Last class we discussed different materials, their structure, properties and applications Structure and properties of metals are controlled by different processing techniques The ductility and malleability of metals allow for unique processing Blacksmiths utilized these techniques for centuries Many (but not all) metals can be processed to improved mechanical properties Modern processing relies on the use of deformation and heat, but with more control than the smiths had The resulting microstructure gives insight into the properties
Background image of page 2
Metals Processing: Summary
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Metal Processing Methods Cast products 1. Melt metal 2. Cast to final shape in a mold (investment casting or lost wax) Powder metallurgy (PM) 1. Form metal into a fine powder 2. Compact powder and sinter or hot press at high temperature (>0.5 of the melting temperature, T M ) Other specialized forming methods: Chemical vapor deposition (CVD) Superplastic deformation at high temperature Electroforming Melt spinning
Background image of page 4
Other Processing Methods Mechanical processing Cold working Hot working Thermal processing Annealing Recovery, recrystalization and growth Heat treatments Both of these are used to control properties of the final product
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cold Working - Strain Hardening Material properties can be altered by processing a material so that it’s grain or phase (crystal) structure changes Cold Working Plastic deformation of metal below the softening or recrystallization point, but commonly at or about room temperature Reduces the amount of plastic deformation that a material can undergo in subsequent processing and requires more power for further working Increase in σ y and hardness - method for strengthening many metals Can make the material brittle Extent of cold working: reduction in area or reduction in thickness %CW = 100(A o – A)/A o or %CW = 100 (d o – d)/d o Achieved by forging, rolling, extruding, and drawing
Background image of page 6
Metal Forming Methods Forging : Pressing of a solid sample in a die to produce a desired shape. This can be done by a single continuous compression or by multiple successive shocks Rolling : Pressing of a sample through sets of parallel rollers, which may also impart a particular shape to the metal Extrusion : Pushing a solid sample through an orifice die by means of a piston or screw pushing a ram Drawing : Similar to extrusion, but the sample is pulled through an orifice by means of a tensile force applied at the down-stream end of the process
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Metal Working Methods Change in cross-sectional area %CW = (A 0 – A)/A 0 x 100 Forging Extrusion Drawing Rolling A o A o A o A o A A A A
Background image of page 8
How Cold Working Works Control of the dislocations in the material The yield strength is completely controlled by the
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 26

BioEng 498 lecture 6 - Metals II: Processing &...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online