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UNCLASSIFIED 

.n 414490 

DEFENSE DOCUMENTATION CENTER 

FOR 

SCIENTIFIC AND TECHNICAL INFORMATION 

CAMERON STATION. ALEXANDRIA. VIRGINIA 



UNCLASSIFIED 


HCTICE: When government or other drawings, sped* 
flections or other data are used for any purpose 
other than In connection with a definitely related 
government procurement operation, the U. S. 
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obligation whatsoever; and the fact that the Govern¬ 
ment may have formulated, furnished, or in any way 
supplied the said drawings, specifications, or other 
data is not to be regarded by implication or other¬ 
wise as in any manner licensing the holder or any 
other person or corporation, or conveying any rights 
or permission to manufacture, use or sell any 
patented invention that may in any way be related 
thereto. 



3 - * - 


Oi 1 


Technical Report No. 299-236 
Copy No. 


DEVELOPMENT OF FINE DIAMETER HIGH-PURITY 
WIRE FROM ZONE-REFINED BERYLLIUM 


O a 


A. G. Gross, Jr. 
R. G. O'Rourke 


Final Report* 
January, 1963 


O 

05 




Contract NOw 62-0067-c 

* Addendum No. 1, January, 1963. This addendum to the 
final report contains room temperature tensile properties 
for the wire which was produced from zone-refined beryllium. 


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Technical Report No. 299-236 


DEVELOPMENT OF FINE DIAMETER HIGH-PURITY 
WIRE FROM ZONE-REFINED BERYLLIUM 


by 


A. G. Gross, Jr. 
R. G. O'Rourke 


Final Report* 
January, 1963 


Prepared under Navy, Bureau of Naval Weapons 
Contract NOw-62-0067-c 


The Brush Beryllium Company 
Cleveland, Ohio 


* Addendum No. 1 
report contains 
wire which was 


, January, 1963. This addendum to the final 
room-temperature tensile properties for the 
produced from zone-refined beryllium. 


TABLE OF CONTENTS 


Page 

I. Introduction.1 

II. Experimental Procedure.2 

III. Results and Discussion.3 

IV. Summary and Conclusions.11 








LIST OF TABLES 


Table No. Page No. 

VI. Room Temperature Tensile Results for As-Drawn 

Wire from Crystal D. 4-5 

LIST OF FIGURES 

Figure No. Page No. 

20. The Variation in As-Drawn Yield Strength With 

Wire-Drawing Strain.6 

21. The Variation in As-Drawn Tensile Strength With 

Wire-Drawing Strain.7 

22. The Variation in As-Drawn Ductility With Wire- 

Drawing Strain.8 







I. INTRODUCTION 


This addendum to the final report presents the results of the tensile 
testing which was performed on as-drawn specimens from crystal D. 

These specimens have been described on pages 50 and 51 of the final report. 





II. EXPERIMENTAL PROCEDURE 


Stock was cropped from each end of sample D. 2b at each of 12 
diameters which ranged from 0.03176-inch to 0.00407-inch. These 
wires were cut into tensile specimens and were tested in the "as-drawn 
with lubricant" condition at room temperature. 




III. 


RESULTS AND DISCUSSION 


The results of the tensile testing are presented in Table VI. 

The values from Table VI have been plotted on logarithmic coordinates 
and these graphs are shown in Figures 21, 22, and 23 for yield strength, 
tensile strength, and elongation, respectively. Also in these figures are 
values for wire which was fabricated from commercially-pure, block-pressed 
beryllium. The block-pressed data are the same as were shown previously in 
Figures 18 and 19 of the final report. Note that Figures 21, 22, and 23 include 
the 95% confidence limits on the mean values for everything except commer- 
cially-pure elongation. The 95% confidence limits on the commercially-pure 
elongation are exceptionally broad. They are approximately ± 1.00% elonga¬ 
tion. 


The yield and tensile strength data for commercially-pure beryllium 
plot such that a straight line may be struck through the points with fair confi¬ 
dence. There are indications that a curve with two or more inflections might 
be a better choice, but the confidence limits are too broad to justify this choice 
in preference to the straight line. 

The yield and tensile strength data for zone-refined beryllium plot such 
a curve with at least one inflection is the mandatory choice of a first approxi¬ 
mation. A dashed straight line which has the same slope as the commercially- 
pure line has been struck through the zone-refined data to emphasize the 
similarity of general trends. 

The pronounced inflection in the zone-refined data suggest that the inflec¬ 
tions which are indicated by the commercially-pure data are probably real also. 
These inflections infer that the strengthening sequence proceeds by unique 
stages which are separated by pauses for structural adjustments. The struc¬ 
tural adjustments would probably be changes in the subgrain (or "cell") 
configuration, or a recovery thereof, thus decreasing the effective grain size 
while renovating the capacity for subsequent work-hardening. The major 
component of the driving force for such changes would be the wire-drawing 
strain-energy. This strain energy would be diverted from producing strain¬ 
hardening so as to be consumed for the structural adjustment. 

Such an interpretation might be dismissed as invalid for either or both 
of the following reasons: 


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TABLE VI 


ROOM TEMPERATURE TENSILE RESULTS FOR AS-DRAWN 
WIRE FROM CRYSTAL D 


c 

Mean Value ±95% Confidence Limits 
_(for the Mean 1 *)_ 


Wire a 

Diameter 

(inch) 

Wire b 

Drawn 

Strain 

No. 

of 

Tests 

Yield at 
0.2% 

Offset 
(x 10 3 psi) 

Tensile 
Strength 
(x 10 3 psi) 

Elongation 

(%) 

0.03176 

1. 75 

6 

62.9 

70. 3 

0. 28 




±2.3 

±2.7 

±0. 13 

0.02712 

2.06 

7 

57. 6 

73.9 

0. 65 




± 1.2 

± 1.3 

±0. 08 

0.02197 

2.48 

7 

63.9 

81.0 

0. 75 




± 1.9 

±0.7 

±0. 13 

0.01688 

3. 01 

8 

69. 2 

86.8 

0.81 




±2.5 

± 1.7 

±0. 15 

0.01297 

3.54 

8 

79.6 

98. 1 

0.98 




± 1.5 

±2.3 

±0. 17 

0.01051 

3.95 

14 

86. 1 

104.8 

1. 21 




±2.6 

± 1.9 

±0. 13 

0.00807 

4. 50 

15 

84.4 

98.4 

1. 11 




± 1.5 

± 2. 1 

±0. 17 

0.00654 

4.90 

15 

83. 3 

96.3 

1.02 




± 1.3 

± 1.8 

±0. 16 

0.00588 

5. 11 

14 

82. 2 

93.9 

0. 78 




±2.7 

±2.2 

±0. 17 

0.00530 

5. 32 

14 

82.8 

94. 3 

0.71 




± 3. 1 

± 4. 1 

±0. 16 

0.00477 

5.54 

10 

87. 1 

95.5 

0. 54 




± 3.9 

±4.7 

±0.12 

0.00407 

5.85 

14 

80.9 

87.0 

0. 34 




±2.5 

±2.8 

±0.05 


(Continued on next page. ) 


4 


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TABLE VI (Continued) 

ROOM TEMPERATURE TENSILE RESULTS FOR AS-DRAWN 
WIRE FROM CRYSTAL D 


-' a Wire was tested in the "as-drawn with lubricant" condition. 

A 1.00-inch gage length was used for all diameters except 
for the 0.03176-inch diameter where a 1.40-inches gage 
length was used. A strain rate of 0. 100 in./in./min. was 
employed in an Instron model TT-C-L machine. 

^Measured from last anneal. Wire Drawn Strain is expressed 
as Ln (reduction ratio). 


c 

Average for specimens from each end of the length of wire 
being drawn. Statistical analysis indicated no difference 
between ends and the results from both ends at each sampled 
diameter were averaged to yield one mean value. 


**Note that the confidence limit is on the "mean value", not on 
the distribution of the individual determinations. 


5 











I 




6 


Fig. 21 The Variation in As-Drawn Yield Strength With 
Wire-Drawing Strain 



7 


Fig. 22 The Variation 










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20NE-REFMED 
(CRYSTAL 0, SAMPLE 










1. The data for the zone-refined beryllium show only one 
strengthening stage. This would not be enough to allow con¬ 
clusions to be drawn with much confidence. 

2. The ductility of the zone-refined material falls continuously 
at the highest wire-drawing strains. 

With respect to the first reason it might be noted that the commercially-pure 
data may be viewed as consisting of three strengthening stages if one accepts 
the existence of inflections in these data. Further, the zone-refined data may 
be taken to consist of one strengthening stage plus the beginning of second 
stage if the datum point at the highest strain level is either discounted or 
assigned to some other effect. The fact that the zone-refined material has 
fewer structural adjustments per increment of strain than does the commer- 
cially-pure material would be compatible with the larger magnitude of each 
adjustment and with the higher mobility of dislocation arrays (such as grain 
boundaries) in zone-refined beryllium. 

The second reason is perhaps the stronger of the two because it is 
difficult to rationalize within the structural adjustment interpretation and 
because it might be taken to suggest that damage such as microcracks is 
being introduced at the high strain levels. Of course there is the plausibility 
that the decrease in the effective grain size (during structural adjustment) 
proceeds in the zone-refined material to the point where even a small amount 
of subsequent tensile deformation at room temperature induces serious dis¬ 
location pile-ups at the newly formed effective grain boundaries. This could 
lead to crack formation and fracture at low values of room-temperature 
tensile strain. Such an argument would be supported by the continuous de¬ 
crease in the tensile-minus-yield-strength difference at the higher strain 
levels. 

This structural-adjustment interpretation has been presented for the 
purpose of suggesting concepts for future work. The data which are reported 
herein do not justify a confident acceptance of this interpretation. It is hoped 
that work which is in progress under Navy Contract No. NOw 63-0137-c will 
extend the data (at least for the commercially-pure wire) to higher strain 
levels. This extension may help to clarify the details of the strengthening 
path but will not necessarily clarify the interpretation of this path. 

There are several points which are illuminated by the resuits in this 
report. First, the difference in work-hardening rate between commercially- 
pure and zone-refined beryllium which was indicated in Figures 18 and 19 of 


9 






the final report is not real. The data for the lowest level of strain for 
crystal 31 were apparently non-representative. Upon reviewing the 
information at this strain level, it was found that the two tensile specimens 
from which the data were generated were tested in the Virgo descaled and 
pickled condition while the rest of the test samples were not cleaned after 
wire drawing. Thus, the comments in the first paragraph on page 49, 
final report, should be accepted as valid. 

Another point is the relative strengths of the three materials. The 
commercially-pure beryllium is the strongest and the 7-pass, zone-refined 
beryllium is the weakest. The 6-pass, zone-refined beryllium is at an 
intermediate strength level. This sequence is the expected one and increases 
the confidence in the strength data for wire from crystal 31. 

The final point is that the wire which was fabricated from zone-refined 
beryllium has about the same as-drawn ductility at room temperature as 
does the commercially-pure wire. 


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IV. SUMMARY AND CONCLUSIONS 


Wires from zone-refined crystal D were tensile tested at room 
temperature. These wires were tested in the as-drawn-with-lubricant 
condition. Tensile properties of the wire from crystal D were deter¬ 
mined as a function of wire-drawing strain. 

These tensile data were compared to similar data for commercially- 
pure beryllium wire. 

It was found that, on the average, the zone-refined beryllium work- 
hardened at about the same rate as did commercially-pure beryllium. The 
room temperature strength level of the zone-refined material was about 
half that of the commercially-pure wire. Room temperature ductility in the 
as-drawn condition was not very purity-sensitive. 


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