dahl Alloy Testing Results
Since the original lead-free legislation took effect in California in 2010, there have been a number of new lead-free brass alloys introduced in an effort to improve production efficiencies.
While improved production efficiencies are very attractive prospects for any manufacturer, some of these alloys are very new and have a limited track record of field performance.
So which lead-free brass alloy should we choose?
Since our customers rely on us for consistent industry-leading quality, there is only one we can choose.
THE BEST.
The only way to determine the quality of any brass alloy is to subject it to independent, rigorous lab tests intended to make it fail.
So dahl selected 5 lead-free brass alloys that are in use today and performed the following laboratory tests:
The following tests were performed:
- Dezincification Resistance ISO 6509
- Stress Corrosion Cracking Resistance ASTM G37
- Brandl Test at 0, 15 and 30 ppm ammonia
The dahl lead-free brass alloy outperformed all other alloys so convincingly that it was simply no contest as to which one is best.
Dezincification
Test ISO6509-1981 ( E )
Test Protocol
- 24 hour test performed by immersing samples in solution of CuCL2.2H2O and subsequently measuring dezincification depth in microns.
- Lower “Average” means better dezincification resistance
| Alloy | Longitudinal | Average Longitudinal | Transverse | Average Transverse |
|---|---|---|---|---|
| dahl Alloy | Nothing measurable | <5 | Nothing measurable | <5 |
| Material A | 956.6, 947.7, 935.0, 936.8, 904.2 | 936 | 1063, 1072, 1060, 1074, 1112 | 1076 |
| Material B | 113.2, 122.3, 114.6, 90.82 | 110 | 394.4, 361.1, 370.1, 389.9, 375 | 378 |
| Material C | Nothing measurable | <5 | 93.6, 92.2, 106 | 97 |
| Material D | 487.1, 522.3, 512.4, 479.9, 555.6 | 511 | 488.1, 486.2, 463.7, 497.1, 498.0 | 487 |
Stress Corrosion Cracking Resistance
ASTM G37-98 (2012) “Mattson’s Solution Test”
Test Protocol
- 1000 hour test performed by immersing samples in test solution and subsequently inspecting for cracks
- 9 samples of each material submitted for testing. Samples comprised of 3 sub-groups.
- Subgroups based on torque levels used to attach a bolt to the machined bar sample.
- Torque levels were 25, 35, & 45 ft-lbs respectively
- Daily inspection of samples for the first week, then twice per week until 1000 hours of exposure time
- Once a crack detected (partial), time is noted and then test continues until crack has fully penetrated (full) through the sample wall
| dahl Alloy | Material A | Material B | Material C | Material D | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Torque in ft-lbs | Partial | Full | Partial | Full | Partial | Full | Partial | Full | Partial | Full |
| 25 | None | None | None | 93 | None | None | None | 826 | None | None |
| 25 | None | None | None | 70 | None | None | 423 | 494 | None | None |
| 25 | None | None | None | 70 | None | None | 755 | 826 | None | None |
| 35 | None | None | 47 | 93 | 24 | 139 | 257 | 328 | None | None |
| 35 | None | None | 47 | 70 | 47 | 139 | None | 328 | None | None |
| 45 | None | None | 24 | 70 | 24 | 139 | 139 | 162 | 664 | 830 |
| 45 | None | None | 47 | 70 | 47 | 139 | 162 | 257 | 664 | 830 |
| 45 | None | None | 47 | 70 | 24 | 139 | 162 | 257 | 760 | 830 |
Numerical values in the table above indicate the number of hours until either a partial or full crack occurred.
3 lines for each torque level illustrates the results for the 9 samples of each material.
Brandl Test
Stress Corrosion Cracking / Dezincification Test
Test Protocol
- Samples are machined to specific dimensions and are set up in test cells
- Stresses are induced on the samples within the cells equivalent to 28% of the material yield strength
- Samples are anodically polarized to 0.4V within the cell
- A test solution, in our case comprised of tap water taken from a municipality known to have harsh water, along with varying degrees of ammonia concentration. Ammonia concentrations of 0 ppm (parts per million), 15ppm & 30 ppm, are introduced into the cell with the sample.
- The test duration is 200 hours and measures dezincification and stress corrosion cracking on the samples for each varying degree of ammonia concentration
| dahl Alloy | Material A | Material B | Material C | Material D | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Ammonia in ppm | Depth (mm) | SCC (mm) | Depth (mm) | SCC (mm) | Depth (mm) | SCC (mm) | Depth (mm) | SCC (mm) | Depth (mm) | SCC (mm) |
| 0 ppm | .08, .12 | None | .86, .77 | None | .78, .80 | None | .24, .30 | None | .27, .28 | None |
| 15 ppm | .11, .13 | None | .80, .94 | None | .86, .89 | None | .27, .31 | None | .25, .26 | None |
| 30 ppm | .13, .11 | None | .82, .80 | None | .95, 1.00 | None | .32, .28 | None | .30, .30 | None |
Lower “Depth” means better dezincification resistance
