- A BRONZ1 WHITE PAPER -Lead-free brass alloy
Registered in ASTM, UNS No.C49355, C89720
Copyright 2012 Joetsu Bronz1 corporation

11. Introduction
For nearly three decades, Joetsu Bronz1 Corporation has been manufacturing and merchandisingcopper alloy ingot and continuous castings. In response to the needs of lead-free copper alloy inrecent years, we are the first manufacturer who have started manufacturing continuous casting oflead-free bronze in Japan. This alloy has been registered in ASTM B584 as a copper alloy C89844,
and has become the forerunner of present bismuth copper alloys family. (Shown in TABLE1)
TABLE 1
PLUMBING COPPER ALLOYS - NOMINAL CHEMICAL COMPOSITION ( wt％ )CAST / LEADED COPPER ALLOYLeadZinc
Silicon Bismuth Phosphorus Selenium
7.0
9.0
5.0
5.0-

Copper AlloyｓCopper
C84400 81.0
C83600 85.0Tin
3.0
5.0

C3560061.5-

WROUGHT / LEADED COPPER ALLOY
2.536.0---

C89520
C89844
C89836

86.0
85.0
89.0

5.5
4.0
5.5

CAST / BISMUTH COPPER ALLOY
5.01.98.0
3.0
3.02.5-0.95-C49300
NEXTBRASS C49355

60.066.0

WROUGHT / BISMUTH COPPER ALLOY
1.536.0
1.2
1.0
31.0
1.50.7--C87850

76.0-

CAST / SILICON COPPER ALLOY
20.93.0-

0.12-C6930075.0-

WROUGHT / SILICON COPPER ALLOY
21.9
3.0-

0.10

-

Copper alloys like bronze and brass have been used for plumbing components such as fittings andvalves with the excellent chemical characteristics. Typically, better machinability is required forproduction of these products and thus, we have kept on adding lead as a content of alloy to obtainsuch better machinability as required.
However, lead content tends to be restricted in recent years so that lead has been recognized as
harmful element which affects the human body and gets worse environmental health bylead-leachate from water contact surface of plumbing components containing lead element into
drinking water and or by the vaporization during melting and casting process. In the USA, newlead content regulation will be enforced on January 1 2014.
Now lead-free copper alloy is mainly classified into bismuth copper alloys family and siliconcopper alloys family. We focused on followings for a new alloy development on the ground ofmaterial supplier,
1) Both of scraps can be used for cost reduction. 2) Both each other characteristics are held.
Upon our continuous study and experiment for five years, we have finally succeeded in thedevelopment of a new lead-free copper alloy that fused with bismuth copper alloy and siliconcopper alloy. This alloy is registered into ASTM.

(UNS No.C49355, C89720)

Copyright 2012 Joetsu Bronz1 corporation

22. Features and related background in bismuth copper alloys family, silicon copper alloys family
and NEXTBRASSIn order to compare and consider with each alloy, we need to start understanding the featuresand related background of each alloy.

We would like to introduce basic knowledge andinformation for you to understand these alloys as follows.
2.1 Influence to the health[Lead]
Lead is contained in copper alloys used for water pipes and plumbing components. Lead
leaches into a drinking water as lead ion from plumbing components. As the consequence of theintake of drinking water with lead ion for a long term, lead poisoning may be caused.
[Bismuth/ Silicon/ Tin]
On the other hand, bismuth, silicon and tin are not restricted elements. No information
warning the risk of drinking water including these elements is published.
2.2 Basic physical properties of each element and effectiveness of additives to copper alloy
Bismuth itself is very fragile compared with lead which has a big ductility.
Neither bismuth nor lead is in solid solution in an alloy and thus, they remain in a liquid stateeven below the each melting point when the alloy solidifies. And they exist in granular on thematrix of an alloy as single element respectively. Because these work as a chip-breaker whenmachining, chip will be smaller and as a consequence, an improvement of machinability will beexpected. However, the addition amount can be considered as the factor for deterioration of hot
workability and thus, it is not preferable to add too much. In addition, it might be a factor fordeterioration of not only hot workability but also mechanical properties.
Furthermore, each cubic volume increases when solidifies, these have effect to bury micro
porosity which is in a place where the supply of molten metal is difficult. These can also makepressure resistance improved.
Silicon itself is very fragile. Silicon in copper alloys works as deoxidizing agent at the time of themelting. This can improve fluidity of molten metal and castability.
In addition, a part of it forms a solid solution in the matrix, and can make mechanical strength
increased. Then, a part of it works together with zinc and makes hard phase functioned as achip breaker, but which can provide machinability less than that of bismuth and lead. Tin incopper alloys contributes to an improvement of erosion corrosion resistance and dezincification
resistance Especially, tin is well-effective for the improvement of erosion corrosion resistance.

Copyright 2012 Joetsu Bronz1 corporation3

2.3 Features of bismuth copper alloys family and silicon copper alloys family
Mechanical properties, corrosion resistance, machinability and hot workability are very
important factors when considering the merit and demerit of lead free copper alloy for plumbing
components. So each property will be briefly introduced as follows.
① Dezincification resistance and erosion corrosion resistanceBoth bismuth copper alloy and silicon copper alloy don’t have β-phase because of matrix
constitution. So these alloys don’t cause dezincification but erosion corrosion easily occurs insilicon copper alloy. (Shown in TABLE2)

Copper Alloyｓ

PLUMBING COPPER ALLOY
CAST / BISMUTH
COPPER ALLOYWROUGHT / BISMUTH
COPPER ALLOY
CAST / SILICON
COPPER ALLOYWROUGHT / SILICON
COPPER ALLOY

C83600C35600TABLE 2
Corrosion ResistanceCorrosion Resistance
Erosion Corrosion ResistanceDezincification ResistanceCorrosion
MaximumMaximum corrosion
weightcorrosiondepth（μm）
loss（g）
depth（mm）
10 or less
0.05
0.25
1200
0.65
0.65

C8984410 or less

0.05

0.30

NEXTBRASS

77

0.15

0.58

10 or less

1.00

0.85

ISO6509-1981

Original Test

Original Test

C49355C87850C69300
Test method

About dezincification phenomenon
The brass, which contents zinc at 30 ~ 40 wt%, is composed of α-phase consisted of more copperand β-phase consisted of more zinc. Dezincification preferentially happens in β-phase prior to
α-phase and copper in red sponge condition is residual.
About erosion corrosion
It is the phenomenon of decreasing wall thickness in plumbing components. That occurs uponinteraction with “erosion” caused by mechanical factor and “corrosion” caused by chemical factor
from high pressure overheated water and steam through the plumbing. The typical case of thisphenomenon can be found in bending portions of plumbing such as elbows and tees.
②Hot workability
Bronze including C89844 cannot be material for hot working. Against it, brass can be used for
hot working originally. Silicon copper alloy can be used as the material for hot working, since its
composition is close to brass. Brass containing a small amount of bismuth instead of lead can bealso used for hot working. However, the addition of large amounts of bismuth tends to inhibit thehot workability.
Copyright 2012 Joetsu Bronz1 corporation

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TABLE 3

Machinability index
Copper Alloyｓ
PLUMBING COPPER ALLOY
CAST / BISMUTH
COPPER ALLOYWROUGHT / BISMUTH
COPPER ALLOY
CAST / SILICON
COPPER ALLOYWROUGHT / SILICON
COPPER ALLOY

C83600C35600Machinability Index
100
130

C8984490

NEXTBRASS

C4935590

C87850102
C69300
Original Test

③ Machinability
In bismuth copper alloy, the granular bismuth is in to disperse without form a solid solution andis served as a chip breaker. This causes good machinability. On the other hand, in silicon copper
alloy, the hard intermetallic compound which exists dispersedly is served as a chip breaker, andcauses good machinability. However, since the intermetallic compound of silicon copper alloy isharder than bismuth and lead, it is expected that the life of cutting tools becomes short. (Shownin TABLE3)④ Mechanical Properties
Silicon copper alloys family is superior to bismuth copper alloys family like C89844 in thestrength at room temperature. (Shown in TABLE4)TABLE 4
ROOM TEMPERATURE - MECHANICAL PROPERTIES

C83600Ultimate Tensile Strength(MPa)310

Elongation(%)
34

C35600360

36C89844

290

33490

23

Copper Alloyｓ
PLUMBING COPPER ALLOY

CAST / BISMUTH
COPPER ALLOYWROUGHT / BISMUTH
COPPER ALLOYNEXTBRASS

C49355

CAST / SILICON
C87850COPPER ALLOY
490
27
WROUGHT / SILICON
C69300COPPER ALLOY
The result is a representative value. Specimens were collected from the test piece was castCopyright 2012 Joetsu Bronz1 corporation

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2.4 Features ofNew alloy “NEXTBRASS”“NEXT BRASS” C49355 (for hot working)Dezincification resistance......................excellent
Erosion corrosion resistance...................excellent
Hot workability..............................excellent
Machinability........................ almost equivalent to bismuth copper alloy
Mechanical properties…………..…almost equivalent or superior to bismuth copper alloy
Recyclability.................scrap of both bismuth copper alloy and silicon copper alloy can be used
3. Technical point regarding new alloy component design
We, Joetsu Bronz1 Corporation, specialized in supplying ingot, rods and bars, have continuously
researched and developed new alloy for a long time upon our concept and idea, that we canproduce at lower cost by using various scrap and also that we can satisfy overall properties based
upon silicon copper alloy, of which feature can be found in the mechanical strength. Through ourresearch and development for a long time, we, Joetsu Bronz1 Corporation, have finally andsuccessfully developed new alloy. The points to design contents of new alloy are shown below.
1 Silicon copper alloy has excellent mechanical properties, dezincification resistance and hot○workability, but erosion corrosion resistance is inferior. Minimum content of tin to improveerosion corrosion resistance shall be 0.5wt%.
② Adding large amount of tin to improve erosion corrosion resistance causes mechanicalproperties(especially elongation for ductility) lowered and hot workability also lowered too since
the best temperature range of hot working becomes narrow. We have improved them bycontrolling content of zinc equivalent to 40 – 43wt%, which enables us to obtain the best
mechanical property and hot workability.
③ In addition, the mechanical properties will be the best by less than 20% of area ratio of κ-phasewithin the range of composition adjusted as indicated above.
④ By reducing the amount of silicon to adjust zinc equivalent, hard phase area working as a chipbreaker is reduced and that causes less machinability. Adding bismuth will recovermachinability.
⑤ We have finally succeeded in the development of new alloy based on silicon copper alloy which
complements each disadvantages of current bismuth copper alloy and silicon copper alloy, andmakes it possible to use copper alloy’s scraps including bismuth and or silicon.
Copyright 2012 Joetsu Bronz1 corporation

64. Conclusion
According to our research and examination as explained so far, we, Joetsu Bronz1 Corporation,
switched our research and development of lead-free products to the copper silicon alloy from thetraditional bismuth copper alloy. Then we have finally succeeded in development of new alloy“NEXTBRASS” (UNS No.C49355, C89720) which can overcome the disadvantages in siliconcopper alloy.
This alloy is economically practical, can satisfy the regulation to restrict lead, and has
fundamental properties equivalent to traditional alloy.
We believe that this new alloy is the best alternative to the traditional ones in the worldwidemarket.

Copyright 2012 Joetsu Bronz1 corporation

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