The Mechanical Properties of Brass Alloys: A Review ^†

Abstract

Brass is a proportionate copper and zinc alloy that may be mixed to achieve a variety of mechanical, electrical, and chemical characteristics. Compared to bronze, it is more pliable. Brass has a comparatively low melting point (900–940 °C; 1650–1720 °F), depending on its composition. This review explores the most recent advancements in brass alloy technology, including the addition of silicon, tin, and aluminium to improve its strength, machinability, and resistance to corrosion. Furthermore, the development of lead-free, recyclable, and low-carbon brass alloys has been fuelled by the growing demand for environmentally friendly materials. With a renewed emphasis on antibacterial qualities and wear-resistant formulations, brass alloys are also seeing increasing use in sectors like electronics, architecture, and healthcare. Additionally, new opportunities for producing custom-designed brass components have been made possible by the development of additive manufacturing. This paper provides an overview of the current and future potential of brass alloys, highlighting their originality in addressing the changing demands of modern industry and technology.

1. Introduction

Brass is not biodegradable due to its comparatively high stability. However, it is reusable multiple times. Brass is one of the most prevalent types of commercial alloy metals used in production and consumption. It possesses qualities that make it ideal for electrical wiring, electrical components, heat exchangers, and so on [1]. Copper and copper alloys are among the most widely used commercial metals for both production and consumption. However, adding brass enhances their machinability even when compared to pure copper. As a result, it is apparent that zinc-containing brass makes materials harder. By preventing softening and raising the recrystallization temperature of copper, silver makes it tougher. It also enhances the electrical and thermal conductivity of the material [2]. Thus, a current endeavour is an attempt to add silver to brass and investigate the mechanical properties of the alloy. Dezincification and dealuminisation are processes that lead to the corrosion of brass and aluminium brass in certain aqueous environments. Adhesive bonding is hampered by copper’s propensity to form brittle amine compounds when combined with amine curing chemicals, which are frequently used to cure many adhesive systems [3]. Sandblasting and hand sanding are examples of abrasion treatments that can provide surfaces with good initial bonding. Nevertheless, this type of surface typically does not result in robust, enduring interactions [4]. The zinc content is higher in brass that has been kept at room temperature for extended periods of time. Copper alloys can be produced using the process described below, along with black oxide, ferric sulphuric/sulphide acid, nitric acid, zinc oxide, and sulphuric acid. Many people believe that there is not anything new to learn about brass because it is one of the oldest alloys still in widespread usage today [5]. Brass is essentially necessary in industrial manufacturing because to several characteristics. It is inexpensive and simple to make using forging, casting, and machining techniques. It has several uses in most kinds of hydraulics and, when alloyed correctly, shows remarkable corrosion resistance [6]. It also possesses significant mechanical properties, particularly remarkable ductility during sheet formation. The usage of lead as an alloying element in brass is the most evident and urgent problem. Brass’s hot workability and, more specifically, its machinability are greatly improved by lead additions of up to around 3%, which also make brass more economically competitive [7]. However, environmental concerns are casting serious doubt on whether lead should be used in any setting, which is why a number of alternate choices are being actively investigated. Brass is one of the most recycled metals in the world, which paradoxically presents an even greater environmental concern because lead used in modern items is also recycled. Although lead can be easily added to brass, there is not yet a workable or affordable method to remove it. The primary means of observing the corrosion mechanism is the seasonal cracking of brass used in construction. Following extended exposure to the atmosphere, the corroded surfaces take on a greenish hue. It is mostly necessary to monitor this applications in architecture [8]. Tin is one of the supplementary elements added to brass in addition to iron and manganese to create a high-strength brass alloy. To make brass more machinable, lead is added in proportions of around 2% to the brass. Some brass alloys appear red due to a larger proportion of the copper content (85–90%). In contrast, the brass in BS 70 ASTM B-214 has a yellowish tint due to a reduced copper percentage (71–74%). An AAS (atomic absorption spectrometer) is used to measure the chemical contents’ sieve values. When dry, brass remains strong. Furthermore, it does not decompose. Abrasives, adhesives, and car parts, such as brake linings, antennae, connections, radiator applications, etc., are among its principal uses. This paper reveals that the strength of brass alloys lies in their ability to adapt and evolve in response to the demands of various industries. With advancements in alloy compositions, corrosion resistance, and sustainability and new applications like additive manufacturing, brass continues to be an essential material. These innovations ensure that brass alloys remain a viable and attractive choice to meet many modern technological, industrial, and aesthetic needs.

2. Brass and Alloys

The conventional furnace melting method is used to create brass. Additionally, zinc can be added to mixtures of materials like tin to give them particular qualities. Lead brass is created by mixing lead with brass. When alloying elements are added, the yield strength rises but the hardness falls in the areas in which they are employed. However, to get around this, adding silver and brass to copper improves the yield and tensile strength but lowers the percentage of elongation. Ultimately, it was determined that the yield strength increased by 3% and 17%, respectively, as the proportion of brass climbed from 3% to 9%. Aluminium and other alternatives to the more conventional dental casting alloys based on gold have recently surfaced, including dental castings based on copper. These copper alloys still seem dazzling and gold in the mouth, but they are less expensive than gold alloys [9]. In one study, every alloy failed to achieve the desired characteristics, with the exception of brass alloys, from which the zinc content would not leak out. Newly created brass alloys have the potential to help with osteogenesis, bone fixing, cell viability development, and bacterial infection prevention. Lead brass alloys have great machinability and corrosion resistance and can be used for radiation shielding. Some of these qualities have been determined morphologically, using an EDX test [10]. Bimetallic brass (CuZn) and other brasses have been extensively studied regarding how relevant their mechanical and physical properties are to possible applications. The gamma brass phase was found to be relatively stable, with crystal sizes dropping by 20 nm and alloying durations rising to 40 h. Regarding the chemical combustion of gamma brass, it was discovered that a brass alloy’s chemical composition consisted of 65.56% Zn and 34.4% Cu (by weight percentage). The microstructural evolution and stability during synthesis and processing helped to achieve this after 40 h of milling, and the amorphous stage was not reached by the end. Under the described experimental circumstances, a nanocrystalline Cu5Zn8 brass phase was formed by the mechanical alloying of Cu–Zn elemental powder and the high-energy ball milling of Cu5Zn8 brass. The findings indicated that the brass phase exhibited a high degree of stability. The crystals shrank by approximately 20 nm over a 40 h milling/alloying period and had a higher BPR (30:1). Moreover, the heating action during the milling of the described low-melting intermetallic alloy caused recovery and high diffusivity with this nanoscale microstructure and operating temperature, resulting in steady-state grain sizes larger than 8 nm.

3. Production Process

The production of implants and Br components involves a crucial casting procedure. One study looked at how adding alloying elements affects the mechanical properties of two different materials: brass alloys and copper alloys. The alloys’ chemical compositions are described in [11]. Ultra-fine-grained pure copper was created through a cryorolling process, and it underwent additional heat treatment to enhance its mechanical qualities, including its tensile strength and ductility. A small percentage of chromium was added to increase the tensile strength, but at the expense of decreasing the electrical conductivity, based on studies on how cold working processes affect Cu-Ag alloys’ microstructure as well as their mechanical and electrical characteristics [12]. The tensile strength of each material was evaluated for specimens at room temperature using the GUNT Universal Testing Machine made in Germany [13], which moved the crosshead continuously at a speed of 2 mm/min. The sample strain was measured and calibrated using an extensometer after it was loaded. Tensile tests were performed on cylindrical specimens with a 6 mm diameter and a 30 mm gauge length for the E-Cu and C3 at room temperature. With extremely high thermal and electrical conductivity, copper is a ductile metal. Pure copper has a low hardness, is pliable, and is soft. Industrial machinery, plumbing, roofing, and electrical wires are the main uses for copper [14]. Brass and bronze can be made by adding alloying metals like zinc and sulphur with copper to increase its hardness. Alloys can have a coating put on their surface to prevent corrosion. The substrates are shielded from corrosive surroundings and corrosion by coatings. Although chromate-containing films have been used in the past, they are currently prohibited due to their negative environmental effects [15].

4. Mechanical Properties of Brass Alloys

The mechanical characterization of brass alloys and its physical and chemical properties were shown in

Table 1. Mechanical characterization of brass alloys.

S. No.	Properties	Brass
1	Density	8.49 g/cm3
2	Elastic modulus	97 Gpa
3	Yield strength	124–310 Mpa
4	Ultimate strength	338–469 Mpa

and

Table 2. Brass alloys: physical and chemical properties.

S. No.	Properties	Brass
1	Solubility	Insoluble in water
2	Melting temperature	930 °C
3	Explosive properties	Low explosive point properties and ductility
4	Oxidising properties	Will react exothermically if mixed with strong oxidising substance

. The CuZn39Pb3 alloy’s beta phase may have a distinctive plate-like shape with distinct orientations among the individual grains [16]. The kind of copper alloy (CuZn39Pb3 and CuZn36Pb2As alloys) and cutting speed had the most effects on the quality of chip production during the machining of brass bars, according to experimental results. Changes in the feed rate and the depth of the cut had no effect [17]. An effort was made to modify CW511L brass’s microstructural properties by utilising several casting moulds. Different microstructures were obtained as a result of the variations in the heat transmission coefficients between the moulds. The average grain size was the point of variation in the component’s microstructural characteristics [18]. Figure 1 depicts the microstructure of brass. Graphite (Gr) and titanium (Ti) were added to Cu-40Zn brass in an experiment, and it was found that simply adding Gr to the alloy improved its cutting performance while gradually degrading its mechanical qualities. However, by combining the two additions, the necessary mechanical characteristics were preserved, and precipitation and dispersion strengthening mechanisms were able to materialise as nano Ti clusters and Cu₂Ti₄O particles. [19,20]. The effects of the cutting parameters, such as the cutting speed, feed rate, and the depth of the cut, on C34000 leaded brass were examined using an analysis of variance (ANOVA) technique [21].

5. Corrosion Properties of Brass Alloys

Brass alloys, primarily composed of copper and zinc, are known for their corrosion resistance. Figure 2, shows the types of brass alloys. The Powder Metallurgy (PM) process, an alternative to conventional casting and forging, allows for precise control over the material properties and microstructure, as shown in Figure 1, which directly influence the corrosion behaviour of brass [22]. Brass alloys produced via Powder Metallurgy exhibit good corrosion resistance, especially when processed to minimise their porosity and surface imperfections. By tailoring the alloy composition, optimising the sintering parameters, and applying surface treatments, PM brass components can achieve performance comparable to or even exceeding that of conventionally produced brass in corrosive environments [23].

6. Applications

Brass, a copper and zinc alloy, is frequently utilised in various industries due to its unique combination of properties, as shown in Figure 3 and

Table 3. Mechanical properties of brass alloys.

S. No.	Materials	Properties	Methodology
1	Cu	Highly Malleable and Ductile	Powder Metallurgy
2	UNSC26000	High Tensile Strength	Machine Rolling and Thread Knurling
3	CZ106	Superior Drawing Properties and Ductility	Powder Metallurgy
4	CZ108	Good Cold Heading and Bending Properties	Cold Working
5	CZ112	Harder and Stronger Duplex Structure	Powder Metallurgy
6	CZ132	Good Machinability and Formability	Hot Forging
7	CZ126	High Ductility and Formable Characteristics	Powder Metallurgy

. Its versatility makes it suitable for applications ranging from decorative items to industrial components [24]. Brass resists corrosion and tarnishing, making it ideal for use in marine and outdoor environments [25]. Brass has an attractive, golden appearance that enhances its use in decorative and architectural applications. Brass is easy to machine, drill, and cut due to its ductility and malleability. It has a long lifespan due to its resistance to wear and environmental degradation. Brass is highly recyclable without a significant loss of quality, making it an eco-friendly material for sustainable manufacturing. Brass is non-magnetic, making it ideal for applications in sensitive electronic and precision equipment. Significant improvements in alloy compositions, production techniques, and applications have been achieved by recent research on brass alloys. Even though brass is still a material with many uses, new developments are aimed at improving its sustainability, mechanical qualities, and resistance to corrosion. A comparison with other copper-based alloys, such as bronze, copper–nickel, and copper–beryllium, highlights the compromises between their cost, corrosion resistance, machinability, and strength. Brass alloys continue to be developed, remaining relevant in a wide range of industries and with new applications in 3D printing and healthcare.

6.1. Mechanical Fasteners

The easiest and most popular joining method uses mechanical fasteners like rivets, bolts, and screws. For installation, they usually do not need specific equipment, and many of them can be taken apart for disassembly. Steel fasteners are stronger and more affordable but lack the corrosion resistance and aesthetic appeal of brass [26]. Aluminium fasteners are lightweight and inexpensive, but brass offers superior durability and resistance to tarnishing. Stainless steel is more durable but lacks the decorative appearance of brass. Brass fasteners combine functionality, durability, and visual appeal, making them an excellent choice for applications where corrosion resistance, conductivity, and aesthetics are priorities. While they are not suitable for high-stress or heavy-duty applications, their advantages in decorative, marine, electrical, and industrial environments make them indispensable. By balancing the cost, performance, and aesthetics, brass remains a valuable material for a wide range of mechanical fasteners.

6.2. Adhesive Bonding

An alloy of copper and zinc called brass is frequently utilised in adhesive bonding applications due to its compatibility with various adhesives and its favourable surface properties. Adhesive bonding is an effective method for joining brass to other materials, offering several advantages over traditional fastening or welding. The adhesive bonding of brass offers a versatile, efficient, and aesthetically pleasing method of joining. Proper surface preparation and adhesive selection are key to ensuring durable, high-strength bonds. With advancements in adhesive technology, brass bonding is becoming increasingly popular in industries ranging from construction and manufacturing to electronics and decorative design [27].

7. Conclusions

Brass is a malleable and durable alloy that has played an important role in the history of mankind. It is an ideal choice for a variety of applications ranging from musical instruments to machinery components because of its unique properties, such as corrosion resistance, malleability, and low friction. Different types and grades of brass are capable of being produced, further increasing its appeal in various industries. As a result, brass continues to be a sought-after material in the modern world because of its enduring qualities and charm.