Corrosion Behavior of Zinc Wrought Alloy ZnAl15Cu1Mg (ZEP1510) as a Potential Substitute for Brass and Galvanized Steel

Abstract

The increasing restriction of lead in industrial alloys, particularly in copper–zinc-based materials such as CuZn40Pb2, necessitates the development of environmentally safer alternatives. ZnAl15Cu1Mg (ZEP1510), a zinc-based wrought alloy composed of 15% aluminum, 1% copper, 0.03% magnesium, with the remainder being zinc, has emerged as a promising candidate for lead-free applications due to its favorable forming characteristics and corrosion resistance. This study investigates the performance of ZEP1510 compared to conventional leaded copper alloys and galvanized steel. Corrosion behavior was evaluated using neutral salt spray testing, cyclic climate chamber exposure, and electrochemical potential analysis in chloride- and sulfate-containing environments. ZEP1510 exhibited corrosion resistance comparable to brass and significantly better performance than galvanized steel in neutral and humid atmospheres. Combined with its low processing temperature and high recyclability, ZEP1510 presents itself as a viable and sustainable alternative to brass with lead for applications in sanitary, automotive, and electrical engineering industries.

1. Introduction

Brass, an alloy primarily composed of copper and zinc, is widely used across various industries due to its favorable mechanical properties, corrosion resistance, and excellent machinability. In particular, leaded brasses, such as CuZn40Pb2, have been standard materials in the production of sanitary components, plumbing systems, electrical fittings, and automotive parts for decades. The addition of lead improves machinability and chip breakage, which enhances manufacturing efficiency [1]. However, the growing awareness of the toxicological and environmental risks associated with lead has led to increasing pressure from regulatory authorities to reduce or completely eliminate its usage [2]. The European Union’s REACH regulation and RoHS directives impose strict limits on the allowable content of lead in consumer goods, particularly those that come into contact with drinking water or food [3]. Consequently, the search for lead-free alternatives has intensified in recent years, prompting both academia and industry to explore new alloy systems that can offer comparable performance without the associated health hazards.

Zinc-based wrought alloys have gained attention in this context. Among them, ZEP1510—a Zn-Al-Cu-Mg alloy—stands out as a promising candidate. It is composed of 15% aluminum, 1% copper, 0.03% magnesium, and the remainder is zinc. This composition offers a favorable balance of strength and ductility. Unlike conventional die-cast zinc alloys, ZEP1510 is designed for forging processes, which opens the door to a wide range of manufacturing methods, including forging and extrusion [4]. ZEP1510 has been developed specifically as a lead-free alternative to copper–zinc–lead alloys, such as CuZn40Pb2 [4]. ZEP1510 exhibits several advantages over brass in terms of both processing and sustainability. One of its primary benefits lies in its lower density (~5.7 g/cm³), which translates into weight savings and an increased number of parts per kilogram of material processed. In contrast to brass (CuZn39Pb3), which has a density of approximately 8.5 g/cm³, this results in roughly 33% weight savings per component [4]. From a mechanical perspective, ZEP1510 offers a higher yield strength (~20% above CuZn39Pb3) while maintaining sufficient ductility for industrial forming processes. Moreover, it displays enhanced electrical conductivity (approximately 15% higher than that of standard machining brass), which expands its applicability into the electrical engineering domain [4]. Industrial trials have successfully manufactured components such as bolts, connectors, battery terminals, and rivets through cold forging [5]. In terms of machinability, even though it does not match the superior chip-breaking properties of leaded brass, its performance is deemed acceptable in most practical contexts. Additionally, the alloy’s excellent recycla-bility and potential CO₂ savings of up to 40% compared to brass contribute to its environ-mental and economic attractiveness [6]. ZEP1510 is currently available in rod form, but research is underway to produce wire-based semi-finished products, enabling its use in continuous cold-forming processes [7]. Rollez et al. [8] studied the aging behavior of ZnAl15Cu1 and found that prolonged exposure to 80 °C or 220 °C leads to up to 30% hardness loss due to recrystallization of the η-phase. This highlights the need to consider thermal stability for long-term applications. A study by Montesano evaluated the cavitation erosion resistance of ZnAl15Cu1Mg using ASTM G32 ultrasonic vibratory testing [9]. The alloy was compared to ZA27 and Alzen305, both standard zinc-based die casting materials. Despite its lower hardness, ZnAl15Cu1Mg showed the lowest mass loss rate, indicating superior erosion resistance. The refined microstructure with homogeneously distributed eutectic phases was found to enhance damage tolerance under cavitation stress, making the alloy a promising candidate for fluid power components and wear-critical applications. Overall, ZEP1510 has reached a high level of technical readiness in terms of forming, processing, and mechanical performance. Future efforts should focus on surface functionalization and standardization to enable its widespread industrial implementation.

Zinc and its alloys are known for their effective corrosion protection properties, particularly when exposed to atmospheric or mildly aggressive environments. The primary mechanism responsible for their corrosion resistance lies in the formation of a thin, adherent layer of zinc oxide (ZnO) and zinc hydroxide (Zn(OH)₂) on the surface [10]. These layers are relatively insoluble and provide a protective barrier that slows down further oxidation and metal loss. However, in the presence of aggressive anions (e.g., Cl⁻), localized corrosion such as pitting may occur unless the alloy is stabilized through passivating elements.

Leaded brass is a classical extensively for machining applications. The lead phase, typically present as finely dispersed particles, acts as a solid lubricant during cutting processes, facilitating chip breakage and reducing tool wear. However, lead does not alloy with copper or zinc; it remains insoluble and therefore segregates along grain boundaries [11].

Galvanized steel, which is steel coated with a layer of zinc, is often used for corrosion resistance in structural applications [12]. For the specimens used in this study, the exact thickness of the zinc coating is not known. However, standard galvanized zinc coatings typically range between 2.5–25 µm in thickness [13]. The zinc layer provides sacrificial protection to the underlying steel by corroding preferentially. While effective in the short term, the protective layer can degrade rapidly in environments rich in chlorides or under mechanical stress. Once the zinc is consumed, the exposed steel substrate becomes vulnerable to rapid oxidation. Galvanized steel was included in the comparative study to serve as a common industrial reference.

The three materials examined in this paper—ZEP1510, copper with CuZn40Pb2, and galvanized steel—represent different approaches to achieving corrosion resistance and mechanical functionality. ZEP1510 aims to replace leaded brass with an eco-friendly, warm-formable alloy. CuZn40Pb2 serves as the established industrial standard. Galvanized steel offers cost-effective corrosion resistance, albeit with limitations in highly corrosive or alkaline environments. A scientific comparison of their performance under standardized conditions provides critical insight into the trade-offs and the potential of lead-free material systems.

The innovation of this study is the first comprehensive corrosion analysis of the lead-free zinc-based wrought alloy ZEP1510 under standardized conditions. By comparing it to established materials like CuZn40Pb2 and galvanized steel, the study provides novel insights into ZEP1510’s suitability as a sustainable alternative for industrial applications.

2. Materials and Methods

This section describes the experimental procedures used to evaluate the corrosion behavior of ZEP1510, copper with brass coating, and galvanized steel under controlled laboratory conditions. The tests conducted include salt spray exposure, climate chamber exposure, and electrochemical potential measurements tests.

2.1. Sample Preparation

For all corrosion tests, multiple identical test specimens with chosen materials were prepared. The specimens varied slightly in geometry depending on the test type, but were standardized to expose defined surface areas, as listed in

Table 1. Information about Specimens.

Material	Density in 20 °C [g/cm3]	Surface Area [cm3]	Picture
ZEP1510	5.7	27.34
Copper + brass coating	8.9	21.45
Galvanized steel	7.87	32.16

. The densities used for the calculations were based on literature values and not determined experimentally. The ZEP1510 test specimens manufactured through a three-stage cold forging process. The first stage involved impact extrusion, followed by head upsetting in the second stage, and completed with coining in the third stage. This industrially relevant manufacturing route ensured realistic surface conditions and material structure for corrosion evaluation. In Ref. [4], the authors describe the manufacturing process and parameters in detail. The other two specimens are also manufactured using similar processes. Surface preparation was carried out in accordance with the requirements of each method: ZEP1510 samples were abraded with 600-grit paper before electrochemical and alkaline testing, while copper-based specimens were degreased using acetone. No additional surface treatments were applied prior to salt spray or climate chamber exposure to simulate practical, untreated conditions.

2.2. Salt Spray Chamber Test

The neutral salt spray test (NSS) was conducted according to DIN EN ISO 9227 [14] to simulate accelerated corrosion in a chloride-rich atmosphere (see Figure 1). The test chamber was operated at 35 °C with a constant mist of 5% NaCl solution. The pH of the solution was maintained between 6.5 and 7.2. The samples were exposed for a total of 500 h. Visual inspection and photographic documentation were performed every 24 h.

2.3. Climate Chamber Test

The test in the climatic test chamber is carried out in accordance with the standard DIN EN ISO 6270-2:2017 [15]. The procedure is identical to test 5.2.1 in the salt spray chamber in terms of the number of specimens and test duration. The arrangement of the samples can be seen below in Figure 2. They are suspended in the climatic test chamber using a Teflon thread and plastic hooks. The constant temperature is 40 °C, and the humidity is around 100% with condensation on the samples. In this test, a visual inspection is carried out every 24 h, and photographic documentation is taken. After the test period of three weeks, the samples are measured and weighed again.

2.4. Electrochemical Potential Measurements

The electrochemical measurements for recording the current density–potential curves are carried out on three specimens, each of the ZEP1510 and the copper alloy, in two different electrolytes—3% NaCl, to represent aggressive, chloride-rich environments, and 0.1 M Na₂SO₄, to simulate less aggressive, industrial atmospheres (see Figure 3).

• 3× limit point ZEP in 3% sodium chloride solution
• 3× limit point ZEP in 0.1 molar sodium sulphate solution
• 3× limit point copper alloy in 3% sodium chloride solution
• 3× limit point copper alloy in 0.1 molar sodium sulphate solution

The ZEP specimens are sanded on the contact surface with 600 grit sandpaper before measurement and the copper alloy specimens are degreased using acetone. At the beginning of each measurement, the resting potential UR (the open circuit potential, i.e., the natural equilibrium potential of the sample in the electrolyte without external voltage) is recorded for 1 h. The potential UH (the applied potential, i.e., the externally set voltage during the polarization experiment) then increases successively from −300 mV, starting in the anodic direction. The feed rate is 120 mV/h. Measurements are taken against the standard hydrogen electrode. An order of magnitude of the respective corrosion rates can then be determined. All measurements are carried out with a top-mounted measuring cell, a silver–silver-chloride electrode as the reference electrode and a platinum electrode as the counter electrode. The respective sample acts as the working electrode. The electrolyte is aerated using an aquarium pump.

3. Results

3.1. Salt Spray Chamber Test

All samples were visually inspected at regular intervals. White corrosion appearanc-es, characteristic of zinc-based materials, were observed on ZEP1510 and galvanized steel within the first 48 h. CuZn40Pb2 remained largely unchanged during this period. After 336 h, galvanized steel exhibited dark discoloration and localized red rust, particularly near the edges, indicating breakdown of the zinc coating and the exposure of the steel substrate. In contrast, ZEP1510 maintained a uniform white patina with no red rust detected even after 336 h (see Figure 4). CuZn40Pb2 developed minor brown staining but no structural corrosion damage. The results demonstrate that ZEP1510 offers a protective surface effect similar to galvanized steel but with more stability against red rust progression.

In addition to visual inspection, the weight gain or loss of the samples was determined at the end of the experiment (see

Table 2. The increases and decreases in weight of the samples from the salt spray chamber test.

Specimen	m1 in g	m2 in g	Δm in g
ZEP1510 #1	11.55070	11.57063	+0.01993
ZEP1510 #2	11.55427	11.57881	+0.02454
ZEP1510 #3	11.55858	11.58816	+0.02958
Copper #1	26.75205	26.74909	−0.00296
Copper #2	26.65888	26.65682	−0.00206
Copper #3	26.65290	26.64939	−0.00351
Steel #1	44.19710	44.24296	+0.04586
Steel #2	44.25090	44.29858	+0.04768
Steel #3	44.22474	44.27358	+0.04884

). For each material, tests were conducted in triplicate. ZEP1510 and galvanized steel showed a mass gain due to white corrosion products. Copper alloy exhibited a slight mass loss, indicating limited corrosion.

The mass loss rate and the surface-related mass change were calculated according to DIN 50905 Parts 1 and 2. The material loss rate w was determined using the following formula [16]:

w = 8.76 × (|Δm|/(ρ × A × T))

(1)

with

w = material loss rate [mm/year]

|Δm| = absolute mass difference [g]

ρ = density of the material [g/cm³]

A = exposed surface area of the specimen [m²]

T = exposure time [hours]

In addition, the surface-related mass change was calculated as

ma = Δm/A

(2)

with

ma = surface-related mass change [g/m²]

Δm = mass increase or decrease [g]

A = exposed surface area [m²]

The results are presented in

Table 3. The average removal rate and mass change of the specimens of salt spray chamber test.

Material	w in mm/a	ma in g/m2
ZEP1510	-	+15.9021
Copper + brass coating	0.00409	−1.3240
Galvanized steel	-	+14.7575

. The material removal rate could only be calculated for copper, as a negative mass change was observed exclusively for this material. The calculations were carried out using the mean value of the three test specimens.

3.2. Climate Chamber Test

ZEP1510 and copper performed similarly under cyclic condensation exposure. Minor surface dulling was observed on both materials after 200 h. No pitting or structural degradation was noted on ZEP1510. Copper exhibited light surface oxidation and color change. Galvanized steel, however, developed visible white corrosion and a slight loss of metallic luster. By 504 h, the galvanized samples showed early signs of corrosion underneath the zinc layer at interface zones, especially around drilled holes and cut edges (see Figure 5).

Table 4. The removal rates and weight increases of the samples.

Specimen	m1 in g	m2 in g	Δm in g
ZEP1510 #1	11.55800	11.56087	+0.00287
ZEP1510 #2	11.55511	11.55885	+0.00374
ZEP1510 #3	11.55316	11.55613	+0.00297
Copper #1	26.65380	26.65399	+0.00019
Copper #2	26.64131	26.64160	+0.00029
Copper #3	26.64946	26.64952	+0.00006
Steel #1	44.30928	44.33102	+0.02174
Steel #2	44.23622	44.25632	+0.02010
Steel #3	44.22602	44.25420	+0.02818

shows the respective increases and decreases in weight of the samples after the end of the trial.

The removal rate and the area-related mass change are calculated as in the salt spray chamber test according to Equations (1) and (2). The results are listed in

Table 5. The average removal rate and mass change of the samples in the climatic test chamber test.

Material	w in mm/a	ma in g/m2
ZEP1510	-	2.0554
Copper + brass coating	-	0.0839
Galvanized steel	-	7.2575

. The observed variation in mass change (Δm) of the copper alloy between the salt spray and climate chamber tests can be attributed to the different environmental conditions and corrosion mechanisms. While the salt spray environment led to measurable mass loss due to dissolution and removal of corrosion products, the climate chamber conditions favored the formation and retention of surface oxides, resulting in a slight mass gain.

3.3. Electrochemical Potential Measurements

Results show distinct differences in corrosion resistance (see Figure 6). In the NaCl solution, ZEP1510 exhibited the lowest corrosion current density, indicating superior resistance to uniform corrosion. Its corrosion potential was slightly more negative than copper, but the passivation range was broader, suggesting effective formation of protective layers. In Na₂SO₄ solution, the performance gap widened. ZEP1510 maintained a stable anodic plateau, while copper showed increased current at lower anodic overpotentials, reflecting susceptibility to localized attack. The corrosion rates are calculated using the averaged magnitudes (see

Table 6. The magnitudes of the corrosion rates.

Measuring	log (I/mA·cm2)
Copper in 3% NaCl	5.7 × 10−3
ZEP1510 in 3% NaCl	3.4 × 10−3
Copper in 0.1 molar sodium sulphate solution	3.2 × 10−4
ZEP1510 in 0.1 molar sodium sulphate solution	5.3 × 10−3

).

Averaged mass losses were also obtained after the measurements. In relation to the contact area of the samples with the electrolyte in the top-mounted measuring cell, the mass changes ma are calculated according to Equation (2), see

Table 7. Mass losses of the samples after the current density–potential measurements.

Measuring	Δm in g	ma in g/m2
Copper in 3% NaCl	−0.00110	−0.09
ZEP1510 in 3% NaCl	−0.00319	−0.26
Copper in 0.1 molar sodium sulphate solution	−0.00027	−0.02
ZEP1510 in 0.1 molar sodium sulphate solution	−0.00326	−0.26

. ZEP1510 showed higher mass loss than copper in both electrolytes. This aligns with the electrochemical results and reflects material-specific dissolution behavior.

4. Discussion

As outlined in the introduction of this paper, the corrosion behavior of the zinc-based wrought alloy ZnAl15Cu1Mg (ZEP1510) was investigated in comparison to conventionally used materials such as leaded copper alloy (CuZn40Pb2) and galvanized steel. These materials were selected based on their relevance in sanitary and industrial applications. The aim was to evaluate ZEP1510 as a potential lead-free substitute material and to derive appropriate corrosion protection measures based on the observed test results. In both the salt spray chamber and the climate chamber tests, white corrosion products formed on the surface of ZEP1510 and galvanized steel. These white deposits, primarily zinc hydroxide Zn(OH)₂, are typical of zinc-containing surfaces. Since the test environments offered little to no air exchange, the formation of zinc carbonates was suppressed, resulting in soft, loosely adherent layers. Despite this, such corrosion products are known to have passivating properties, slowing down further corrosion processes through surface coverage. Red rust (Fe₂O₃) developed on the galvanized samples during salt spray exposure, originating from the steel substrate. ZEP1510 did not exhibit such behavior, as no iron was present in these samples. This was attributed to corrosion products originating from adjacent galvanized samples, rather than active corrosion of the brass itself. With respect to long-term application, ZEP1510 exhibits corrosion behavior similar to galvanized steel in terms of white rust formation. However, it provides superior protection against deep red rust progression. This supports its suitability as a lead-free substitute, particularly for interior components exposed to humidity and condensation. The electrochemical tests provided further insight into the corrosion mechanisms. ZEP1510 exhibited slightly higher current densities at open circuit potential compared to copper alloy, indicating a generally higher corrosion rate under these conditions. Nevertheless, the corrosion behavior of ZEP1510 was consistent across both NaCl and Na₂SO₄ electrolytes, suggesting stable passivation behavior. Copper alloy, on the other hand, exhibited a significant difference in corrosion rate depending on the electrolyte. In chloride environments, copper alloy showed a higher corrosion current, confirming its known vulnerability to chloride-induced localized corrosion. In the semi-logarithmic polarization plots, the corrosion rate difference between ZEP1510 and CuZn40Pb2 in sulfate solution was within a single order of magnitude, which is not considered critical. A more pronounced deviation would be required to draw strong conclusions about material superiority in this context. From these observations, it can be concluded that ZEP1510 shows promising corrosion performance in neutral and humid environments, with only minor drawbacks regarding surface aesthetics due to white rust formation. Compared to galvanized steel, it offers better structural integrity under prolonged exposure. While it does not match the visual corrosion resistance of copper alloy, it represents a viable lead-free alternative, especially when combined with simple protective or optical surface treatments.

5. Conclusions and Outlook

From a corrosion standpoint, the zinc-based wrought alloy ZEP1510 does not exhibit any disadvantages compared to galvanized steel and may serve as a suitable substitute in related applications. However, in comparison to the copper alloy, ZEP1510 shows a clear aesthetic drawback due to the rapid formation of white rust on the surface. Without the implementation of additional corrosion protection measures, ZEP1510 cannot fully replace the copper alloy in terms of corrosion resistance, particularly in applications where long-term visual integrity is required.

Future research should therefore explore optimized corrosion protection techniques such as technical coatings, lacquers, or hybrid layer systems tailored to zinc–aluminum alloys. In addition, long-term exposure tests under real atmospheric conditions and the simulation of daily-use environments could provide deeper insight into material performance. This would help validate ZEP1510 as a reliable lead-free alternative for both indoor and semi-outdoor applications, especially in sanitary and mechanical engineering contexts.