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Pg. 3.28-3.33

Published on Nov 18, 2015

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MORE DECKS TO EXPLORE

PRESENTATION OUTLINE

1.

IDENTIFICATION BY APPERANCE

  • Base metals and Alloys can be identified by simple tests and and by characteristic metallic features
  • Ex.) Ferrous metals can be identified by magnetic attraction, surface appearance, structural form or shape
Photo by JD Hancock
2.

METAL LABELING

  • Most shops have a system to label or color-code the types of metals being used.
  • Stainless steel and Nickel alloys: only use low-chloride markers. Others will leave a residue and can contaminate the weld.
Photo by Tim Sheerman-Chase
3.

IDENTIFICATION BY MAGNET:

  • Nonferrous metals: do not contain iron. More resistant to corrosion and nonmagnetic
  • Ferrous metals are mainly composed of iron and have magnetic properties.
  • *Do NOT rely on magnetic testing because of alloys or changes that can occur during welding*
Photo by chrisinplymouth
4.

IDENTIFICATION BY APPEARANCE

  • Identifying metals by appearance is not reliable because most metals have similar characteristics.
Photo by artolog
5.

X-RAY FLUORESCENCE SPECTROMETRY

  • Most reliable
  • 5 seconds
  • Nondestructive
  • Shoots a ray down and it reflects energy back which then displays what type of metal it is.
Photo by geckzilla
6.

THERMAL CONDUCTIVITY

  • Metal's ability to conduct heat
  • Good conductors of electricity are usually good heat conductors
  • As temp increases, so does metal's resistance to heat
  • Poor conductors fail to carry heat away from weld zone
7.

THERMAL EXPANSION

  • Change in size that occurs in a material as temperature changes
  • Solids expand when heated and contract when cooled
  • Large changes cause stress in welds
8.

MELTING POINT

  • Temperature at which a solid becomes a liquid
  • Transition point: point when solid becomes liquid
Photo by Graela
9.

CORROSION RESISTANCE

  • Corrosion can severely reduce tensile strength of a metal
  • Certain metals are not reactive to certain corroding chemicals
  • Some metals produce a protective oxide to prevent excess corrosion
Photo by stockerre
10.

DENSITY

  • The mass of a specific volume of metal
  • The higher the density of a material, the heavier it will be
  • Ex: aluminum- low density
Photo by kevin dooley
11.

ELECTRICAL CONDUCTIVITY

  • Ability of metal to conduct electricity
  • Examples: aluminum, copper
Photo by Furcifer pardalis

Brooke Miller