A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A R C H 2 0 2 3 6 METALS | POLYMERS | CERAMICS Fittle, the financing arm of Xerox Holdings Corp., is partnering with Velo3D Inc. to help customers finance purchases of the company’s metal additive manufacturing Sapphire printers. fittle.com. ARCH Cutting Tools Corp., Bloomfield Hills, Mich., acquired Custom Carbide Cutter Inc., Cincinnati, another cutting tools provider. ARCH serves the medical, aerospace, defense, automotive, energy, agriculture, and general industrial markets with standard and custom tooling. archcuttingtools.com. BRIEFS BONDING WITH STEEL Researchers at The University of Tokyo are pre-treating steel with an acid wash and dipping it in hot water in order to bond polymers to galvanized steel. The scientists discovered that when a polymer was applied to the treatedmetal—in a process called injection-molded direct joining—it filled in the tiny gaps and ridges between and within the needle structures, creating very strong mechanical linkages. The acid wash strips the outer passive layer on the zinc coating of the steel, which allows the hot water to form rough nanoscale needle structures on the true surface. “We found that immersion in hot water was a simple and effective method for producing nanoscale structures on the zinc coating for the polymer to adhere to, but that prior acid-washing to remove the passive layer was a WELD FILLER MATERIALS A new series of weld filler materials was created in a joint effort by the U.S. Departments of Energy and Defense, enabling onsite welding without costly, laborious heat treatments typically used to reduce residual stresses and material distortion. The novel materials could dramatically improve high-strength steel repair in vehicles, bridges, and pipelines. The invention from the U.S. Army and DOE’s Oak Ridge National Laboratory (ORNL), Tenn., solves a major problem of welded steels that occurs when hydrogen atoms enter the metal during weldingand reduce themetal’sductility, toughness, and strength. Subsequently, high tensile residual stress leads to troublesome cracking. To overcome this challenge, scientists at ORNL and DOD’s Ground Vehicle System Center partnered to invent an alloy with a unique chemical composition that can join strong steels while reducing residual stresses. The alloy’s ability to resist hydrogeninduced cracking comes from a novel phase transformation in the weld. As a weld cools, the filler material combats tensile stress, which pulls at steel’s crystalline microstructure to lengthen and break it. The phase transformation then introduces compressive stress as the weld cools. A weld filler needs to be at least as strong as the steel panels it joins. To develop the chemical composition of their pioneering, stress-compensating filler, ORNL researchers ran a theorybased model on high-performance computers. With more efficient algorithms, the computing code ran a thousand times faster than a comparable commercial code, identifying problems in one day versus nearly three years. The inventors used this process to arrive at a filler that works with structural steels of varying strengths and alloy compositions. Characterization of welded materials with neutron diffraction at the High Flux Isotope Reactor, a DOE Office of Science user facility at ORNL, showed remarkable reductions in residual stresses. ornl.gov, army.mil. Researchers developed a simple method of bonding polymers with galvanized steel to create a lightweight and durable product. Courtesy of Institute of Industrial Science, The University of Tokyo. Scientist Yiyu Wang tests and characterizes materials to determine howwelding a ects the microstructure. Courtesy of Carlos Jones/ORNL, U.S. Department of Energy.
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