Influence of Metallurgical Quality of Brass Ingots and Brass Bars (Copper Billets) on the Microstructure and Properties of Sanitary Ware Products [[SMM Copper Conference]]

On April 22, at the CCIE-2025SMM (20th) Copper Industry Conference and Copper Industry Expo—Copper Pipe & Tube and Billet Processing Industry Development Forum, organized by SMM Information & Technology Co., Ltd. (SMM), Shanghai Nonferrous Metals Trading Center, and Shandong Aisi Information Technology Co., Ltd., with Jiangxi Copper Corporation and Yingtan Inland Port Holding Co., Ltd. as the main sponsors, Shandong Humon Smelting Co., Ltd. as a special co-organizer, and Xinhuang Group and Zhongtiaoshan Nonferrous Metals Group Co., Ltd. as co-organizers, Mr. Xicai Lao, General Manager of Guangdong Weiqiang Copper Technology Co., Ltd., shared insights on the impact of brass ingot and brass billet metallurgical quality on the structure and performance of sanitary products. 01 Influence of Metallurgical Quality on Structural Characteristics

Impact on Structural Characteristics

01 Grain Size and Shape

Grain size directly affects the strength and toughness of materials, while grain shape significantly influences the fatigue life of materials. The quantity and distribution of grain boundaries play a critical role in determining material performance.

02 Micro Defect Analysis

Casting Defects: Shrinkage porosity, looseness, gas porosity, and inclusions have a significant impact on the mechanical, processing, and physical properties of materials. Comprehensive control is required in raw material purity, alloy composition design, melting and refining processes, and casting crystallization.

03 Analysis of Structural Uniformity

A uniform structure can enhance the overall performance of materials, while structural non-uniformity can lead to stress concentration and performance degradation. Uniformity is crucial for the corrosion resistance of sanitary products.

Grain Size and Shape

► Impact of Grain Size

Coarse grains have less total grain boundary area, weaker grain cohesion, and reduced strength and toughness, as well as decreased corrosion resistance and weldability. Conversely, relatively fine grains can achieve better mechanical, physical, and processing properties.

► Impact of Grain Shape

Equiaxed Grains in Casting: Good isotropy, suitable for deformation processing. During the process, the addition of modifiers is required to suppress the growth of columnar grains.

Columnar Grains: Arranged in a specific direction, with good axial strength but reduced transverse plasticity and fatigue resistance, prone to defects such as shrinkage porosity and cracks.

Grain size and shape directly determine mechanical properties, processing performance, and environmental resistance by influencing dislocation movement, grain boundary characteristics, and structural uniformity. Through the synergistic optimization of composition design (e.g., microalloying) and process control (e.g., rapid solidification, cold working rate, and heat treatment regimes), grain structure control can be achieved, thereby improving metallurgical quality.

Phase Composition and Distribution

Microstructural characteristics of the a+β phase: The a+β phase exhibits excellent comprehensive properties; the a phase, with a face-centered cubic crystal structure, demonstrates superior plasticity and is suitable for cold working; the β phase, with a body-centered cubic crystal structure, exhibits high hardness and low plasticity, making it suitable for hot working.

Microstructural characteristics of the Pb phase: The Pb phase is distributed in the form of fine particles at grain boundaries or phase boundaries, playing a role in chip breaking and self-lubrication during machining, reducing tool wear, improving surface finish, and enhancing machining efficiency.

Influence of phase interface distribution: Uniform phase composition and distribution significantly impact the mechanical properties, machinability, and surface treatment of the material; segregation of the β phase and Pb phase can lead to local stress concentration, significantly reducing strength, corrosion resistance, and fatigue resistance, as well as causing unstable adhesion to coatings, affecting aesthetics and long-term corrosion resistance.

02 Influence of Metallurgical Quality on Physical Properties

Influence of Brass Ingots and Brass Bars on the Performance of Sanitary Ware Products

► Influence on the microstructure of brass products

Density and uniformity of the microstructure: During the solidification process of high-temperature molten metal, volume shrinkage occurs. If not promptly supplemented, shrinkage cavities (porosity) will appear at the last solidified areas. Non-uniform solidification leads to the presence of coarse columnar grains and dendritic crystals in the crystalline structure, often accompanied by looseness, pores, and inclusions between grains, which will affect the forging and machinability of the material.

► Influence on the performance of sanitary ware products

Strength and toughness: High-quality brass provides better mechanical properties. Corrosion resistance: Brass with good metallurgical quality exhibits superior corrosion resistance. Machinability: Good brass materials offer high machining efficiency, reducing production costs.

► Influence on the durability of sanitary ware products

Wear resistance: High-quality brass demonstrates better wear resistance, making the product more durable. Fatigue resistance: Good brass materials perform better under repeated stress. Weldability: The welding performance of brass affects the durability of the product.

► Changes in Machinability

1. Surface treatment performance (electroplating and corrosion resistance)

An excellent copper semis substrate ensures good polishing performance, freedom from impurities and pores, perfect adhesion to coatings, and aesthetic durability.

2. Formability (cold/hot working performance)

Microstructure affects formability; a uniform microstructure facilitates various forming processes; an uneven microstructure can easily lead to fracture and affect dimensional accuracy.

3. Optimization of welding performance

Welding methods influence welding performance; optimizing welding parameters improves welding performance; appropriate welding materials can enhance welding performance.

03 Impact of Metallurgical Quality on Alloy Trace Elements

►Microalloying Effect

04 Opportunities and Challenges for Brass Bars and Copper Ingots in the Sanitary Ware Industry

►Application Prospects of Brass and New Materials in Sanitary Ware Products

Application of Brass Bars in Sanitary Ware Products: In 2024, brass bars, with their excellent corrosion resistance and good processing and forging properties, have broad application prospects in sanitary ware products. Their unique color and texture after polishing and electroplating make sanitary ware products appear more high-end and elegant, and they also exhibit excellent performance in terms of environmental protection and durability.

Potential of Copper Ingots in the Sanitary Ware Industry: Copper ingots, due to their excellent casting properties and durable stability after polishing and electroplating, are widely used in the manufacture of high-end sanitary ware bodies. With the improvement of living standards and the segmentation of high-end customized markets, the application areas of copper ingots will become more concentrated in the mid-to-high-end range, bringing new development opportunities to the sanitary ware industry.

Impact of New Materials on Sanitary Ware Products: The emergence of new materials, such as stainless steel and zinc alloys, will have transformative impacts on the cost, design, function, and performance of sanitary ware products. The application of these new materials will drive a new round of reshuffling in the market segments of the sanitary ware industry.

05 Quality Requirements for Brass Materials in High-End Sanitary Ware Products

►Special Requirements of the Sanitary Ware Industry for Brass Materials

1. Control of Gas and Non-Metallic Inclusions

During the melting process, various metallic compounds that are insoluble in the matrix metal may be present, whether from the raw materials or from tools, furnace linings, or fluxes, leading to the formation of granular, flaky, or blocky inclusions in the material. These inclusions seriously affect the polishing and electroplating performance of sanitary ware products.

Weiqiang's Solution: Adopting ultra-cold crystallisers and a grain refinement refining process to ensure that the metallographic grains of the casting ingots are fine, uniform, and dense.

2. Control of Harmful Impurities

Elements such as S, Sb, and Te are harmful during the melting process. These elements are almost insoluble in copper and form high-melting-point brittle compounds with copper at the grain boundaries, increasing the brittleness of the material and affecting its processability. Based on European and American regulations regarding the control of harmful elements to human health, it is necessary to verify and control these harmful elements during the smelting of raw materials.

Weiqiang's Solution: Implementing strict selection, impurity removal, and classification processes for raw materials; and employing multiple unique degassing and slag removal refining processes during the melting process to ensure quality.

3. Casting Liquidity

High-quality copper ingots possess good casting liquidity, which is particularly important for the manufacture of sanitary ware products. Good liquidity ensures that the copper alloy can fully flow within the mould, filling every detail of the mould, thereby guaranteeing the shape and dimensional accuracy of the product.

Weiqiang's proposal: In terms of casting liquidity, precise control is exercised over melt purification, grain refinement, and the control of various elements.

►The significance of brass in enhancing the quality of high-end bathroom products

• Improving product performance and reliability

Lead is slightly soluble in copper in a solid state, with the majority existing in copper in a granular form. This enhances chip formation and wear resistance. However, during the smelting process, it is necessary to control the lead content, particle size, and distribution to achieve good chip formation and wear resistance.

Bathroom products have high requirements for the corrosion resistance of copper alloys, such as resistance to dezincification corrosion and stress corrosion cracking. This necessitates control over the metallurgical microstructure and the alloying of special elements. Obtaining more equiaxed grains and adding elements (such as As, Sn, etc.) can achieve better corrosion resistance.

• Enhancing the surface quality of brass bathroom products

The performance of materials, in turn, affects the service life and applicability of products, especially in humid environments. The design requirements of bathroom products are closely related to the performance of brass materials, influencing the feasibility and innovation of product design. The durability and oxidation resistance of electroplated products directly impact brand reputation and customer perception.

• Green, environmentally friendly, and sustainable development

The metallurgical quality of copper alloys, particularly the control of harmful element content, is crucial for ensuring the health and safety of bathroom products. Developed countries and regions have imposed strict limits on lead content in drinking water systems to reduce health risks to humans. The metallurgical quality of copper billets also relates to environmental protection issues. After discarded, lead-containing brass can easily release lead into the soil and atmosphere, causing environmental pollution. Therefore, the use of low-lead or lead-free copper alloy materials is of great significance for reducing environmental pollution. The development of environmentally friendly copper alloys reduces the use of harmful substances and is more friendly to the environment and human health. The use of such materials enhances the safety and market competitiveness of bathroom products.

In addition, it introduces the high-end brass products of Guangdong Weiqiang Copper Industry.

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