US2011114227A1PendingUtilityA1
Grain refinement of metallic components by controlled strain path change
Assignee: DE ALMEIDA GRACIO JOSE JOAQUIMPriority: May 28, 2008Filed: May 27, 2009Published: May 19, 2011
Est. expiryMay 28, 2028(~1.8 yrs left)· nominal 20-yr term from priority
Inventors:José Joaquim De Almeida GrácioEdgar Fernand RauchFrederic BarlatJeong-Whan YoonGabriela Vincze
C21D 11/00C21D 7/00C22C 38/00C21D 7/04C21D 7/02C21D 9/46C22C 21/00
38
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Claims
Abstract
Nowadays, the production of metallic parts, namely sheet metal, with high strength and formability, represents a big challenge for automotive, aerospace and assembling industries. The present invention deals with a new plastic deformation process that allows, by controlling the strain path change, the production of sheet metals with a grain size of 1-2 micron and, consequently, with a yield stress 3-4 times than the ones obtained with conventional processes, keeping the same formability. The process is easy for industrialization and its optimization requires only two fundamental parameters that characterize the ratio of thickness reduction, shear strain and amplitude in the change of strain path.
Claims
exact text as granted — not AI-modified1 . Process of grain refinement by controlled strain path change under compression simple shear plastic deformation during successive steps were the relative speeds of the upper and lower rolls are alterated.
2 . Process of grain refinement by controlled strain path change under compression simple shear plastic deformation during successive steps were the relative speeds of the upper and lower rolls are alterated, according to claim 1 , with special emphasizes in sheet metal.
3 . Process of grain refinement by controlled strain path change under compression simple shear plastic deformation, according to claim 2 , occurring the process in at least 2 working stations where the relative speeds of the upper and lower rolls are alterated.
4 . Process of grain refinement by controlled strain path change, according to claim 1 , wherein an amplitude of the change in strain path (α) is lower than 0.5.
5 . Process of grain refinement by controlled strain path change, according to claim 4 , wherein an amplitude in the change in strain path (α) is located in the range −0.13-0.5.
6 . Process of grain refinement by controlled strain path change, according to claim 5 , wherein an amplitude in the change in strain path (α) is located in the range −0.13-0.13.
7 . Process of grain refinement by controlled strain path change, according to claim 1 , wherein, a parameter “a” higher than 1 is expressed by the following relation between the thickness reduction ratio r and the apparent shear strain γ app :
γ
app
=
a
r
(
2
-
r
)
2
(
1
-
r
)
2
.
8 . Process of grain refinement by controlled strain path change, according to claim 7 , wherein a parameter α is in the range 1.2-2.5, as expressed by the following relation between the thickness reduction ratio r and the apparent shear strain γ app :
γ
app
=
a
r
(
2
-
r
)
2
(
1
-
r
)
2
.
9 . Process of grain refinement by controlled strain path change, according to claim 8 , wherein a parameter “a” is in the range 1.75-2.5 as expressed by the following relation between the thickness reduction ratio r and the apparent shear strain γ app :
γ
app
=
a
r
(
2
-
r
)
2
(
1
-
r
)
2
.
10 . Process according to claim 2 further comprising production of metal sheets with thickness reduction ratios higher than 500%.
11 . Process according to claim 2 further comprising production of sheet metals with grain sizes around 1-2 micron that can be stabilized by thermal treatments at low temperatures.
12 . Process according to claim 2 further comprising production of sheet metals with a yield stress 3-4 higher than the one obtained in conventional processes without alternating the relative speeds of the rolls, keeping the same degree of formability.
13 . Equipment for grain refinement of metallic parts by controlled strain path change according to claim 1 , including one or more working stations where the material is plastically deformed under compression-simple shear and where the relative speeds between the upper and lower rolls are alternated after each pass.
14 . Metallic part produced according to claim 1 , including a grain refinement, obtained as a result of controlled strain path, plastic deformation by compression simple shear in successive steps and alternating the relative speeds of the upper and lower rolls after each deformation step.
15 . According to claim 14 , wherein the metallic part is a metal sheet.
16 . According to claim 15 , wherein the metal sheet is steel or aluminum sheet.Join the waitlist — get patent alerts
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