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Improvement in Superplasticity by Boron Additions

IP.com Disclosure Number: IPCOM000078253D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 16K

Publishing Venue

IBM

Related People

Marshall, JC: AUTHOR [+2]

Abstract

A major criteria for good superplastic forming is a high value of the strain-rate sensitivity index "m", as described in the equation: (Image Omitted)

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Improvement in Superplasticity by Boron Additions

A major criteria for good superplastic forming is a high value of the strain- rate sensitivity index "m", as described in the equation:

(Image Omitted)

Zn-Al, Zn-Cu and Zn-Mn alloys have high values of "m" at some composition levels and process conditions. However, the value of "m" is often degraded at low and intermediate strain-rates, even in these alloys. This can complicate the forming cycle considerably.

It has been found that small amounts of boron restore the high "m" value at lower strain-rates and even raise it at higher strain-rates. Successful results have been obtained by using an addition of 0.02% boron added as an Al-3% B or Cu- 2% B master alloy. It is estimated, however, that additions as low as 0.005% B can be beneficial. There has been added up to 0.1% B without any deleterious effects and at least part of the effect is due to the fact that the boron getters titanium, in which case, boron should be added at a level of at least three times the titanium level.

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