Lead-free, cadmium-free, high-corrosion-resistance | KEEPALLOY ZC Metal
▼ Types and features
ZC metal-1: Lead-free, cadmium-free high-corrosion-resistance brass bars for forging These are high-corrosion-resistance brass bars for forging that have superior hot-forging properties and can be given dezincification corrosion resistance through the specified treatment after hot forging. This is material that complies with "C6803" regulated by JIS H 3250 (Copper and copper alloy bars) and "C49300" regulated by ASTM B124, B249 and B967.
ZC metal-2: Lead-free, cadmium-free high-corrosion-resistance brass bars for cutting These are high-corrosion-resistance brass bars with superior dezincification corrosion resistance, mechanical properties, and cutting properties. This is material that complies with C6803 dezincification-resistant free-cutting brass bars "C6803BD-FRD" regulated by JIS H 3250 and "C49300" regulated by ASTM B249 and B967.
* ZC metal is material that complies with the revised American Safe Drinking Water Act (SDWA) and the related NSF/ANSI 61.
▼ Specifications comparison
Properties
KEEPALLOY ZC metal
Free-cutting brass bars C3604
Brass bars for forging C3771
Bronze casting CAC406 and CAC406C
Dezincification corrosion resistance
Erosion-corrosion resistance
Mechanical properties
Cutting properties
Machinability
Surface roughness
Hot-forging properties
-
-
◎=Superior, ○=Equal, ×=Inferior
▼ Chemical composition (representative example) (%)
Material
Cu
Bi
Sn
Fe
Special elements
Pb
*Cd
Zn
ZC metal
60.2
1.2
1.2
0.1
0.4
0.01
10 ppm max.
Residual
C3604
59.0
-
Sn+Fe 1.0
-
3.2
General spec.
Residual
Less than 75ppm
C3771
59.0
-
Sn+Fe 1.0
-
2.5
General spec.
Residual
Less than 75ppm
CAC406
85.0
-
5.0
0.3
-
5.0
-
5.0
▼ Mechanical properties (representative example)
Application
Material
Manufacturing method (size)
Properties
Tensile strength (N/mm²)
0.2% yield strength (N/mm²)
Elongation (%)
Hardness (HV)
Charpy impact value (J)
Brass bars for forging
KEEPALLOY ZC metal-1
Extruded (ø30)
412
183
33
110
21.0
C3771
Extruded (ø33)
350
140
45
90
25.8
Brass bars for cutting
KEEPALLOY ZC metal-2
Drawn (ø26)
407
227
30
110
18.5
C3604
Drawn (ø24)
450
340
26
140
30.0
Bronze continuous cast bar
CAC406C
Continuous cast bar (ø30)
286
-
33
65
-
* JIS Z 2201 #4 test pieces were used for the tension test. * JIS Z 2202 2mm U-notch test pieces were used for the Charpy impact test.
▼ Dezincification corrosion resistance
Test method
ISO 6509 / JIS H 3250 Annex A
Evaluation standard
Maximum depth of erosion: 200μm
Test result
KEEPALLOY ZC Metal-1 (forged products)
KEEPALLOY ZC Metal-2 (bars)
C3771 (forged products)
C3604 (bars)
CAC406C (bars)
ISO ×200
ISO ×200
ISO ×50
ISO ×50
ISO ×200
Maximum depth of erosion：33μm
Maximum depth of erosion：15μm
Maximum depth of erosion：1380μm
Maximum depth of erosion：1450μm
Maximum depth of erosion：10μm
β, γ phase column type corrosion
γ phase column type corrosion
Layer corrosion
Layer corrosion
-
* KEEPALLOY ZC Metal-1 forged products are subject to the specified heat treatment after forging. * Dezincification corrosion tests for bars were all conducted with cross-sections of bars.
Evaluation results
KEEPALLOY ZC Metals comply with the evaluation (maximum depth of erosion 200μm) .
▼ Erosion-corrosion resistance
Test method
Gap jet corrosion test method
Test results
Material
ZC metal-1 (forged products)
ZC metal-2 (brass bars)
C3771 (forged products)
C3604 (brass bars)
CAC406C (bronze continuous cast bar)
Photograph of surface after 5 hours
Corrosion form
Layer corrosion
Layer corrosion
Ring corrosion
Ring corrosion
Layer corrosion
Depth of erosion (μm)
71
55
620
430
56
Mass loss (mg)
100
250
480
500
240
Evaluation results
KEEPALLOY ZC Metals are materials that have superior erosion-corrosion resistance. They corrode uniformly overall with the same kind of layer corrosion as CAC406C.
▼ Stress corrosion cracking resistance
Test method
Apply a threading tensile stress to a joint for evaluation that has been machined to add a tapered female pipe thread, by applying a certain torque to a bushing that has been machined to add a male thread. Observe how many hours it takes before cracks occur on the surface in an atmosphere of 14% ammonia. By testing under the same conditions, it is possible to make relative evaluations between the material being evaluated and the comparison material.
The photograph below shows an example in which a stainless steel bushing is mounted on the brass material being evaluated.
Test conditions and judgment standard
Samples
Test material that has been machined to add Rc1/2 pipe tapered thread (See photograph.)
Bars
Forged products
Partner material
Bushing SCS13A 1/2×3/8 ... PB(1)1/2
Tightening torque
9.8 N･m
Atmosphere
Normal temperature ammonia atmosphere (14% NH3 solution)
Judgment standard
Observe visually and with stereoscopic microscope to see whether or not there are cracks. ○: No cracks observed △: Cracks observed (Cannot be judged visually, judge with stereoscopic microscope) ×: Cracks observed (visual judgment)
Test results
Material
Judgment results for each corrosion duration
4H
8H
12H
24H
36H
48H
KEEPALLOY ZC Metal-2 (bars)
C3604 (bars)
Material
Judgment results for each corrosion duration
24H
72H
168H
KEEPALLOY ZC Metal-1 (forged products)
C3771 (forged products)
Evaluation results
Compared to C3604 (brass bars for cutting), KEEPALLOY ZC Metal-2 (brass bars for cutting) has about the same or better stress corrosion cracking resistance. Compared to C3771 (forged products), KEEPALLOY ZC Metal-1 (forged products) has about the same or better stress corrosion cracking resistance.
▼ Hot forgeability
Test method
Upset test After a test piece in the figure below was heated to the test temperature, it was compressed with a press machine to the pre-determined upset ratio, then the material was evaluated by checking visually for cracks in the surface of the test piece.
Test results
Material
KEEPALLOY ZC Metal-1
C3771
Photograph
Temperature (ºC)
670
700
730
760
790
670
700
730
760
790
Upset ratio (%)
45
50
55
60
Proper forging temperature (ºC)
740~780
680~740
* For the forgeability evaluation, products with no cracking were judged O and those on which cracks were visible were judged ×.
Evaluation results
KEEPALLOY ZC Metal-1 shows good forgeability over wide ranges of upset ratios and forging temperatures equivalent to those for C3771. The proper forging temperature is a rough yardstick. We recommend that you run test forging with actual work pieces to check the optimum forging temperature first.
Heat treatment conditions for forged products
In order to ensure dezincification corrosion resistance and to eliminate residual stress, after forging, it is necessary to heat treat KEEPALLOY ZC Metal-1 at 450 to 480ºC for the actual metal for 2 hours or longer. The proper forging temperature for KEEPALLOY ZC Metal-1 is 740 to 780ºC, but if it is forged at temperatures over 800ºC, the metal structure becomes needle shaped and the corrosion resistance and mechanical properties may fall.
▼ Machinability
Turning and drilling conditions
Method
Machining conditions
Cutting speed (m/min)
Rotation speed (rpm)
Feed (mm/rev.)
Cutting depth (mm)
Cutting conditions
Turning
113
1,800
0.06
1.0
Dry
Drilling
28
1,500
0.05
-
Dry
Test results and cutting chip observation
Method
C3604
ZC metal-2
CAC406C
Turning
Machinability Rating: 100
Machinability Rating: 71
Machinability Rating: 87
Drilling
Machinability Rating: 100
Machinability Rating: 72
Machinability Rating: 89
* Machinability Rating (%) = ([C3604 cutting resistance value]/[Cutting resistance value for each material]) x 100
Evaluation results
The machinability rating for KEEPALLOY ZC Metal-2 show higher values for cutting resistance than C3604 and CAC406C, but the cutting chips are fine and machining is possible without changing the cutting conditions greatly.
