Formability in Deep Drawing Steel

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Formability in Deep Drawing Steel

• Christopher Melvin
• Washington State University
• 2008

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Steel Coil
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Some Applications Include

• Automotive
• Motor casings
• Building supplies
• Household items

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Deep Drawing

• Drawability- high degree of plastic flow in
  plane, resistance to flow in thickness
• r-value ew/ et (e-true strains)
• r e22/ e33
• q -e22/e11 ew/el
• Where e11 e22 e33 are the normal strains in the
  x, y, and z directions respectively

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Cup Drawing Die
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Cup Drawing Sequence
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Variations of R-Value

• raveFormability parameter
• (normal anisotropy)
• rave rm (r02r45r90)/4
• ?rEaring parameter (planar anisotropy)
• ?r (r0r90-2r45)/2

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Methods to Determine R-Value
Tensile Test rm 1.656 (cntr) ?r 0.9188
VHM Method rm 1.690 (cntr) ?r 0.92365
Company Methods (Module-R) rm 1.662 (ave) ?r
0.703
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Textures

• Most important cause of anisotropic plastic
  properties
• Rolling steel creates a preferred orientation
  (Texture)
• R-value changes with different textures

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Euler Space-ODF
Gamma
Goss
Phi 45º
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ODF-Texture Plot
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Coil Edge (across width)
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Coil Center (across width)
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Edge vs. Center
Edge
Center
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Head vs. Tail (Phi 45)
Head (center)
Tail (center)
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Experimental Cup Profile
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VanHoutte Model
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Cup vs. R-Value Profiles
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Methods to Determine R-Value
Tensile Test rm 1.656 (cntr) ?r 0.9188
VHM Method rm 1.690 (cntr) ?r 0.92365
Company Methods (Module-R) rm 1.662 (ave) ?r
0.703
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Hot Band Microstructure Gradient
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Center vs. Edge Microstructures
Center
Edge
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Conclusion

• Designed cup die to measure earing
• Compared direct measurements to model
• Edge properties differ from center
• Gradient in hot band carries over to cold rolled
• Indications of Goss

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Thanks

• Dr. David Field
• Alankar Alankar
• Dr. Leo Kestens
• Dr. Paul VanHoutte

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Future research

• Obtain model to calculate r-value
• Increase accuracy of where the coupons were
  obtained
• Obtain new samples to test after proposed process
  changes are made