Muntz Metal - Ning

Muntz
Metal

An Analysis of Muntz Metal’s
properties and its Application as a
Building Material

Muntz Metal=
60% copper + 40%
Zinc + small amount of iron

The purpose of adding alloying elements to copper is to optimize the
strength
, ductility (formability), and
thermal stability
, without inducing
unacceptable loss in fabric ability, electrical/thermal conductivity, or
corrosion
resistance
.



The
existence of impurities and all common alloying elements, except for
silver, will decrease the electrical
and thermal conductivity
of copper
.)


Mechanical Properties

Hardness

Muntz Metal

Metric

English

Comments

Hardness, Rockwell F


80

80

Mechanical Properties

Metric

English

Comments

Hardness, Brinell


40.0
-

420

40.0
-

420

Average value: 168
Grade Count:93

Hardness, Rockwell B


26.0
-

200

26.0
-

200

Average value: 88.4
Grade Count:139

Hardness, Rockwell C


29.0
-

44.0

29.0
-

44.0

Average value: 33.5
Grade Count:12

Hardness, Rockwell F


53.0
-

95.0

53.0
-

95.0

Average value: 68.0
Grade Count:37

Hardness, HR30T


6.00
-

82.0

6.00
-

82.0

Average value: 50.6
Grade Count:26

Tensile Strength,
Ultimate


96.5

-

1010

MPa

14000

-

147000

psi

Average value: 485 MPa
Grade Count:302

Tensile Strength, Yield


69.0

-

793

MPa

10000

-

115000

psi

Average value: 290 MPa
Grade Count:256

Elongation at Break


0.000
-

70.0 %

0.000
-

70.0 %

Average value: 23.4 %
Grade Count:297

Reduction of Area


0.000
-

63.0 %

0.000
-

63.0 %

Average value: 28.6 %
Grade Count:33

Modulus of Elasticity


41.0

-

137

GPa

5950

-

19800

ksi

Average value: 109 GPa
Grade Count:256

Compressive Yield
Strength


75.8

-

1610

MPa

11000

-

233000

psi

Average value: 655 MPa
Grade Count:59

Poissons Ratio


0.280
-

0.346

0.280
-

0.346

Average value: 0.324
Grade Count:188

Charpy Impact


2.70

-

88.0

J

1.99

-

64.9

ft
-
lb

Average value: 33.4 J
Grade Count:53

Izod Impact


2.70

-

75.0

J

1.99

-

55.3

ft
-
lb

Average value: 36.0 J
Grade Count:48

Fatigue Strength


90.0

-

352

MPa

13100

-

51100

psi

Average value: 201 MPa
Grade Count:70

Machinability


20.0
-

90.0 %

20.0
-

90.0 %

Average value: 32.7 %
Grade Count:200

Shear Modulus


37.0

-

46.0

GPa

5370

-

6670

ksi

Average value: 42.3 GPa
Grade Count:188

Shear Strength


44.0

-

538

MPa

6380

-

78000

psi

Average value: 297
MPa

Grade Count:102

Bronze

Metric

English

Comments

Hardness, Rockwell F


53.0
-

95.0

53.0
-

95.0

Average value:
68.0

Grade Count:37

•
Rockwell F:
1/16 inch
Brale

indenter60 kg load

•

>> The
hardness value is
above

the acceptable range of the particular
hardness scale.

Indentation hardness measures the resistance of a sample to
permanent plastic deformation due to a constant compression load
from a sharp object

Stainless Steel

Metric

English

Comments

Hardness, Rockwell F


>>

>>

Sheer Strength

Stainless Steel

Metric

English

Comments

Shear Modulus


62.1
–

86.0
Gpa

9000
-

12500
ksi

Average
value
: 78.2
GPa

Grade Count:269

Bronze

Metric

English

Comments

Shear Modulus


37.0
-

46.0 GPa

5370
-

6670
ksi

Average value:
42.3
GPa

Grade Count:188

Muntz

Metal

Metric

English

Comments

Shear Modulus


39.0 GPa

5600
ksi

•
The shear modulus is concerned with
the deformation of a solid when it experiences a force parallel to one of its
surfaces while its opposite face experiences an opposing force
(such as friction).

•
It is defined as "the ratio of shear stress to the displacement per unit sample length (shear strain)" .


Shear Modulus

•
Shear Modulus is the coefficient of
elasticity

for a shearing force. It is defined as "the ratio of shear
stress to the displacement per unit sample length (shear strain)"

•
the
shear modulus

describes the material's response to shearing strains.

•
It is the description of an object’s tendency to be deformed elastically.


Stainless Steel

Metric

English

Comments

Shear Modulus


62.1
–

86.0
Gpa

9000
-

12500
ksi

Average
value
: 78.2
GPa

Grade Count:269

Bronze

Metric

English

Comments

Shear Modulus


62.1
–

86.0
Gpa

9000
-

12500
ksi

Average
value
: 78.2
GPa

Grade Count:269

Muntz Metal

Metric

English

Comments

Shear Modulus


62.1
–

86.0
Gpa

9000
-

12500
ksi

Average
value
: 78.2
GPa

Grade Count:269

Thermal Conductivity (in/hr*ft²*
°
F)

Muntz

Metal

Stainless Steel

Cast

Iron

11.5

9.6

6.0

Thermal Expansion (in²
/
°
F x 10^
-
6)

Muntz

Metal

Stainless Steel

Bronze

852

105.6

180

Specific Heat Capacity

Stainless Steel

Metric

English

Comments

Specific Heat
Capacity


0.200
-

0.620 J/g
-
°
C

0.0478
-

0.148
BTU/lb
-
°
F

Average value:
0.477
J/g
-
°
C

Bronze

Metric

English

Comments

Specific Heat
Capacity


0.375
-

0.450 J/g
-
°
C

0.0896
-

0.108
BTU/lb
-
°
F

Average value:
0.385
J/g
-
°
C

Muntz metal

Metric

English

Comments

Specific Heat
Capacity


0.375 J/g
-
°
C

0.0896 BTU/lb
-
°
F

Corrosion Resistance

•
Copper corrodes at negligible rates in unpolluted air, water, and desecrated non
-
oxidizing acids.
Copper alloy artifacts have been found in nearly pristine condition after having been buried in the
earth for thousands of years, and copper roofing in rural atmospheres has been found to corrode at
rates of less than 0.4 mm in 200 years.





•
Copper alloys resist many saline solutions, alkaline solutions, and organic chemicals. However,
copper is susceptible to more rapid attack in oxidizing acids, oxidizing heavy
-
metal salts, sulfur,
ammonia (NH
3
), and some sulfur and NH
3

compounds



•
Brasses

(C 20500
-

C 28580) are basically copper
-
zinc alloys and are the most widely used group of
copper alloys. The resistance of brasses to corrosion by aqueous solutions does not change
markedly as long as the zinc content does not exceed about 15%. Above 15% Zn,
dezincification

may occur.


Dezincification

•
Dezincification results in a porous, reduced ductility, reddish
copper matrix. What remains may support a given load until an
increase of pressure or weight exceeds the local ductility and
causes fracture.
Soft, stagnant, or slow moving waters or saline
solutions can lead to dezincification of unmodified brasses.
The
brasses may be more prone to dezincification in stressed
regions (for example, in the bent region of a float arm on a
water closet fixture) or where a bend exists (as in an elbow in a
fresh water supply line).

•
High
zinc content introduces the possibility of
stress
-
corrosion
cracking
.

Very high zinc content, as in Muntz metal, may lead to
excessive corrosion attack in seawater due to dezincification.

•
(Limited
or no data are available on the effects of zinc in
brasses on the rate of corrosion; however, the addition of
tertiary and quaternary elements is known to enhance the
resistance of zinc
-
containing alloys to certain environments
.)


Stress corrosion cracking

(
SCC
)

•
Stress
Corrosion

Cracking is cracking due to the process
involving conjoint corrosion and straining of a metal due to
residual or applied stresses


SCC
is the growth of cracks in a
corrosive environment. It can
lead to unexpected sudden
failure of normally ductile
metals subjected to a tensile
stress, especially at elevated
temperature in the case of
metals.




The SCC environment of Muntz

•
Alloys at the higher zinc levels of 35 to 40%
Zn

contain the bcc beta phase,
especially at elevated temperatures, making them hot
extrudeable

and
forgeable.


•
When subjected to the combined effects of stress and corrosion, many
alloys can develop cracks over a period of time and
specifically copper
-
zinc
alloys such as brass can be sensitive to stress corrosion attack, particularly
in the presence of moisture through condensation.
However, SCC occurs
only in the presence of
a sufficiently high tensile stress and a specific
corrosive environment.
For brasses, the environment involved is usually
one containing ammonia or closely related substances such as amines.