Effects of Nickel and Carbon on the Toughness of Precipitation Strengthened Stainless Steel Warren Garrison, Carnegie Mellon University DMR-0400434

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Effects of Nickel and Carbon on the Toughness of
Precipitation Strengthened Stainless SteelWarren
Garrison, Carnegie Mellon University DMR-0400434

• We have investigated the effects of cobalt levels
  of 9,12,15,18 and 21 wt. on precipitation
  strengthening in a system with 0.005C /12Cr
  /5Mo /1.5Ni. Results to right show cobalt
  significantly increases the yield strength.
• We have investigated the effects of austenitizing
  tem- perature, quench rate and refrigeration on
  strength and toughness. We can presently achieve
  a Charpy impact energy of 40J at a hardness of
  53Rc

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Effects of Nickel and Carbon on the Toughness of
Precipitation Strengthened Stainless SteelWarren
Garrison, Carnegie Mellon University DMR-0400434

• In terms of broader impacts we have begun to work
  with Timken Steel, a specialty steel company, to
  develop these alloys commercially for
  applications such as aircraft landing gear, the
  application which motivated our work in this
  system. Timken Steel has presented our results to
  date to Boeing Commercial Aircraft and Boeing has
  expressed an interest in evaluating the
  properties of these alloys, including stress
  corrosion cracking resistance.
• Three undergraduates have worked on this project
  and were supported by our Research Experience for
  Undergraduates grant associated with this grant.
  They have carried out heat treatments, mechanical
  testing, measurements of retained austenite and
  examined fracture surfaces on the scanning
  electron microscope. In addition, a senior did
  his College of Engineering Honors Project
  studying the effect of austenitizing temperature
  on the grain size, strength, toughness and
  fracture mode of these alloys.