Advancing aluminium wheel casting with NUCLEANT* grain refining fluxes
06 Nov 2025
By Gael Zaragoza, Mark Stapleton, Hayati Sahin, Philippe Kientzler
Foseco International Ltd October 2025
Discover superior grain refinement technology for automotive aluminium casting applications. This is a concise overview that explains how the NUCLEANT 158X family of grain refining fluxes offers an efficient and reliable alternative to traditional Ti-B master alloy rods in aluminium casting. It highlights improved grain refinement, reduced additives, cleaner melts, and consistent mechanical properties.
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Summary
Several challenges plague aluminium wheel casting, including porosity, shrinkage, and inconsistent grain structure due to low feedability and undercooling.
Grain refinement is essential for mitigating these issues. This is traditionally achieved using Ti-B master alloy rods, which whilst effective in most applications are higher cost per treatment than the alternative of flux grain refinement Foseco’s NUCLEANT 158X family of grain refining fluxes offers a solution. These Ti-B-based granulated fluxes are introduced during melt degassing, forming fresh titanium diboride (TiB₂) and aluminium boride (AlB₂) particles in situ. This results in a more uniform distribution of the grain refiner, reduced fading, and finer, more consistent grain structures.
Experimental results from wheel foundries show that NUCLEANT-treated castings maintain comparable mechanical properties to those refined with Ti-B rods; however, they require significantly lower addition rates and yield a cleaner melt.
Case studies from real-world applications reinforce these operational benefits. With over 400 million wheels produced using NUCLEANT products globally, these fluxes represent a more efficient and reliable alternative to traditional grain refinement methods in aluminium casting.
Contents
Executive Summary Overview of challenges in aluminium wheel casting and introduction to NUCLEANT grain refinement innovation with key performance benefits.
Introduction Context of Low Pressure Die Casting (LPDC) in automotive manufacturing, emphasising the critical role of grain refinement for castability and mechanical properties.
Technical Background: Some Principles Of Grain Refinement Principles of grain refinement including grain morphologies, undercooling effects, Stokes' Law, and limitations of conventional Ti-B master alloy rods in maintaining consistent performance.
A New Approach To Grain Refinement: NUCLEANT* 158x Grain Refining Fluxes Detailed explanation of NUCLEANT* flux composition, in-situ TiB2 and AlB2 formation mechanism, and advantages over traditional rods including higher efficiency and automation compatibility.
Case Studies Real-world OEM wheel manufacturing applications, demonstrating production scale (400M+ wheels) and successful use in safety-critical automotive suspension components.
Conclusion Summary of technical benefits and operational advantages of the NUCLEANT* family in aluminium casting.
Abstract
Background: Low-pressure die casting of aluminium wheels presents significant metallurgical challenges, including excessive porosity, shrinkage defects, and inconsistent grain structures resulting from low feedability and undercooling phenomena. Traditional grain refinement using titanium-boron (Ti-B) master alloy rods, while effective, exhibits limitations including oxide contamination, grain refiner fading due to particle settling, silicon poisoning in Al-Si alloys, and relatively high treatment costs.
Methods: This paper examines the NUCLEANT 158X family of Ti-B-based granulated grain refining fluxes as an alternative to conventional rod-based grain refinement. The fluxes are introduced during melt degassing operations, forming fresh titanium diboride (TiB₂) and aluminium boride (AlB₂) particles in situ. Experimental validation was conducted at wheel foundries using A360 and A356 alloys with comparison trials between traditional Al5Ti1B rod addition (1 kg/t) and NUCLEANT flux addition (0.55 kg/t). Samples were evaluated for macrostructure homogeneity, grain size, dendrite arm length, mechanical properties (UTS and elongation), and titanium content retention over casting duration.
Results: NUCLEANT-treated castings demonstrated more homogeneous macrostructure compared to rod-treated samples while maintaining comparable grain sizes and mechanical properties. Significantly, NUCLEANT fluxes showed no decrease in titanium content during the casting process, eliminating the fading effect observed with traditional rods. Addition rates were reduced by 30-48% depending on application, with grain size reductions of up to 45% and 19% lower aluminium content in dross. The fluxes provided additional benefits including melt cleaning through oxide removal and compatibility with automated addition systems.
Conclusions: The NUCLEANT 158X grain refining flux family represents a more efficient and reliable alternative to Ti-B master alloy rods for aluminium casting applications. With over 400 million OEM wheels produced globally using these fluxes since 2012, including safety-critical components such as suspension arms and knuckles, NUCLEANT products deliver comparable or superior metallurgical outcomes while reducing grain refiner consumption, eliminating fading, and improving melt cleanliness.
