May 2026 Volume 8

FORGING RESEARCH

IMPROVING FORGING DIE LIFE THROUGH ADVANCED ALLOY COATINGS By Marcus L. Young, Jin Kim, Willow Knight, Sameehan Joshi, Narendra Dahotre, Andy Spires, and Rob Mayer

P rofessor Marcus Young, his team of graduate students Jin Kim and Willow Knight, and Professors Sameehan Joshi and Narendra Dahotre at the University of North Texas recently investigated a new approach to alloy development to improving die life using a laser cladding/surface engineering technique. Rob Mayer and Andy Spires from Queen City Forging provided die materials and industrial testing of the coated dies as well as helped guide the project. The Industry Problem Forging dies suffer from early failure due to wear from extreme pressure and abrasion at higher temperatures (>600 °C). This die failure results in either die replacement which is expensive and wasteful or die repairs which are time-consuming and often ineffective, due to cracking and flaking during follow up use leading to shorter die lifespan. Both die replacement and die repairs ultimately lead to production delays. The goal of this project was to refurbish the worn dies using an improved repair process by adopting laser-based surface engineering for enhanced surface hardness and die life. The Solution: Laser-Cladded Complex Concentrated Alloys (CCAs) To address the problem of die failure, Dr. Young’s research team investigated laser cladding/surface engineering as a processing route for repairing the worn dies by applying a coating of complex concentrated alloys (CCAs) to develop a time-efficient process and effective coating 1 . Recently, a strong research push was made to move away from conventional alloys, which are dominated by one primary element such as Fe or Ni, and explore high entropy alloys (HEAs), which consist of a combination of multiple (5 or more) elements of high concentration (near equiatomic) with no primary element 2-3 . This research approach led to an expansion of the range of properties of alloys. From this effort in HEAs, CCAs emerged as a new class of multi-element alloys, which can have a primary element along with much larger percentages of other elements as compared to conventional alloys 2-6 . A graphical illustration in Figure 1 highlights the transition from conventional alloys and high entropy alloys to complex concentrated alloys. Based on previous insights from the team 7-9 , the researchers at UNT explored iron-based CCAs which exhibited high wear resistance, high strength at higher temperatures, and tunable properties through compositional changes 1 . To apply these CCAs to dies, a laser cladding technique was adopted to bond these alloys onto worn H13 steel forging dies, creating a tough protective surface, as schematically illustrated in Figure 2. The laser cladding process consists of two stages involving preparation of surface and slurry and the second stage involving laser deposition/cladding followed by and polishing the cladded surface for the required finish. This is then followed by evaluation of sacrificial tiles (cladded coupons) and validation

through industrial testing. In the first stage of the laser cladding process, the worn die surface is physically polished to remove any defects (surface cracks, pores, etc.) followed by deposition of a cladding precursor slurry of a CCA material on to the cleaned die surface. After the slurry is completely dried to remove any moisture, it is fused with the substrate die by rastering the laser beam of sufficiently high energy to bond it to the die surface. Finally, the cladded CCA layer is physically polished to create a smooth die surface finish. Laser cladding has several key features: (1) Localized and rapid heating, (2) Strong metallurgical bonding between the CCA clad and substrate die material, (3) Microstructures with evolution of fine directional grains and unique metastable phases due to rapid thermal cycling, (4) Coating thickness typically ranging from 25-250 microns in thickness, and (5) Minimal dilution with the base steel, and (6) Generation of a strong chemical bond between cladding and substrate die material. To achieve the best results, the laser cladding technique was optimized by the researchers at UNT. The optimization process is critical to the success of the CCA coatings. While, less than optimal laser energy input may lead to poor bonding, excessive laser energy input may lead to generation of the physical defects like pores and cracks. The UNT team identified and optimized the key laser parameters, which resulted in the best balance of adhesion, density, hardness, and ultimately wear-resistance [1]. Alloy Design The UNT team used a combination of prior knowledge through a literature review and previous research by the UNT team, CALPHAD simulations, and lab testing to identify two promising CCAs compositions: Fe₀.₃₅Co₀.₂₅Ni₀.₂₀Cr₀.₁₀Ti₀.₀₆Al₀.₀₄ and Fe₀.₃₀Co₀.₃₀Ni₀.₂₀Cr₀.₁₀Ti₀.₀₆Al₀.₀₄ in atomic percent 1-9 . Using the optimized laser parameters, these coatings produced a high surface hardness, a strong metallurgical bonding, and stable microstructures under forging heat. Real-World Industrial Testing H13 steel dies were laser cladded with the above listed CCA compositions and tested by Rob Mayer and Andy Spires at Queen City Forging Company. Typical dies last until about ~19,000 parts before generating damage and excessive wear to continue to use. As an example, the team took one of these dies after service, repaired it, and then cladded it with the Fe₀.₃₀Co₀.₃₀Ni₀.₂₀Cr₀.₁₀T i₀.₀₆Al₀.₀₄ CCA, which resulted in forging 21,000 plus parts and is still in service, as shown in Figure 3. Further microstructural analysis of the die highlights some of the complex stress states across the die (Figs. 3(b)-3(e)) 1 . Thus, the cladded die outlasted standard dies and continues to still produce parts.

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