A summary on materials selection

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A summary on materials selection

• Some of the major factors in the selection of
  materials are
• Strength of the material
• Corrosion resistance of the material
• Joinability of the various pieces
• Formability into the appropriate shapes
• Fracture toughness
• Cost of alloy plus fabrication costs
• Tubing for bicycle frames is made by hot piercing
  the ingot and then
• subsequently cold drawing using a mandrel to
  make the hole in the
• tubing and get the correct diameter and wall
  thickness.
• Cold drawing of the material causes it to become
  work hardened
• Possible materials for the manufacture of a
  bicycle frame and some
• interesting properties are
• yield
  yield/density
• Plain carbon steel 240 MPa
  30
• Cr-Mo steel 485
  62
• 6061-T6 260
  95

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• Al alloy 6061 has the composition Al-1.0Mg-0.6Si.
  It is precipitation
• or age hardenable. The heat treatment
  procedure is to solution treat
• the tubing at 530 C, then quench it, and
  subsequently age it at 160 C
• for 18 hrs.
• The precipitate which forms upon this ageing
  treatment is Mg2Si.
• These second phase particles hinder the motion
  of the dislocations
• inside the material, and the yield strength is
  thus increased from 8
• to 40 ksi.
• Titanium is polymorphic and changes its crystal
  structure at 882 C
• The two most important elements for the alloying
  of titanium are
• aluminum and vanadium.

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• Ti alloys strengthened by

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• Ti alloys strengthened by
• solution hardening

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases
• heat treating (Q age)

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases
• heat treating (Q age)
• martensite transformation

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases
• heat treating (Q age)
• martensite transformation
• EXCELLENT corrosion resistance

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases
• heat treating (Q age)
• martensite transformation
• EXCELLENT corrosion resistance
• Oxygen sponge at moderately elevated temps

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases
• heat treating (Q age)
• martensite transformation
• EXCELLENT corrosion resistance
• Oxygen sponge at moderately elevated temps
• Expensive

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases
• heat treating (Q age)
• martensite transformation
• EXCELLENT corrosion resistance
• Oxygen sponge at moderately elevated temps
• Expensive
• Joining arc welding, TIG, brazing, adhesive
  bonding

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• Ti alloys strengthened by
• solution hardening
• mix of a b phases
• heat treating (Q age)
• martensite transformation
• EXCELLENT corrosion resistance
• Oxygen sponge at moderately elevated temps
• Expensive
• Joining arc welding, TIG, brazing, adhesive
  bonding
• Welding gives HAZ with properties different than
  base material

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• Cr-Mo steel frame weld and HAZ are bainite

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• Cr-Mo steel frame weld and HAZ are bainite
• TIG welded 6061-T6 weld HAZ overaged

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• Cr-Mo steel frame weld and HAZ are bainite
• TIG welded 6061-T6 weld HAZ overaged

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• Cr-Mo steel frame weld and HAZ are bainite
• TIG welded 6061-T6 weld HAZ overaged
• Brazing furnace-brazed w/ Cu-Zn alloy at 900 C
  - frame softened

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• Cr-Mo steel frame weld and HAZ are bainite
• TIG welded 6061-T6 weld HAZ overaged
• Brazing furnace-brazed w/ Cu-Zn alloy at 900 C
  - frame softened

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