Page 14 - MetalForming March 2019

Materials & Coatings
Technology Opens Door to Game-Changing Alloys for Steel Manufacturers
The difference between recrystallization temperatures for the alloy layers and the recrystallization temperature of the core region makes it is possible to keep the alloy layer work hardened while recrystallizing the core alloy.
elongation and corrosion resistant prop- erties, typically difficult to produce. Man- ganese, often added as a strengthening element, represents another element demonstrated by Arcanum Alloys through its SODA platform. Light-gauge materials made with a full-hard-surface alloy high in manganese and a ductile core offer stiff steels with higher elongation than current high-strength low-alloy sheet products.
Customized Corrosion Resistance
The SODA platform allows Arcanum Alloys to customize the chromium content in the alloy at the surface of Optiform. Since corrosion resistance is tied largely to the chromium content of the alloy, Arcanum Alloys controls the corrosion resistance by controlling the chromium concentration in its alloyed surfaces. According to company officials, this spatial optimization brings multiple functionalities and tailored performance not attainable by other means.
For example, when customers require material to pass ASTM B117 salt fog test- ing, Arcanum Alloys alters its production slightly to increase chromium percentage in the alloyed surface. The majority of the Optiform produced now offers corrosion resistance between austenitic 304 stain- less and 316 stainless grades, but the company also produces material for cus- tomers with corrosion performance needs greater than 316 stainless.
Cost, Versatility Advantages
The use of Optiform in appliance parts such as dishwasher and refrigerator doors may result in multi-million dollar savings, according to company officials. Using Opti- form versus 430 stainless steel to reduce springback, scrap rates on certain forms reportedly decreased from 10 percent to 1 or 2 percent for a major-appliance OEM. In addition to such savings, the material has the potential to substantially reduce downtime and press-maintenance require- ments over time.
Further, OEMs are learning that their
A new technology from Kentwood, MI- based Arcanum Alloys, utilizing spatially optimized diffusion alloys (SODA ), is prov- ing to be a disruptive innovation for steel usage, say company officials, pointing to three factors: designed performance, manufacturing versatility and greater func- tionality. Having first developed the tech- nology in Silicon Valley before relocating to the Midwest to be closer to its suppliers and production partner, Arcanum has announced its first product: Optiform, a new stainless steel alloy; validated and tested with multiple customers. Arcanum expects its first production launch by April.
Formability
For metal forming processes, Optiform reportedly offers substantial formability improvement over standard non-spatially optimized ferritic stainless steels. To accomplish this, chromium is diffused into the surface of a proprietary ultra- low-carbon steel substrate, creating a spatially optimized alloyed sheet with a stainless surface and a highly ductile core. Because the ductile core represents the bulk of the material, its mechanical properties dominate the overall mechanical properties of the material. Despite the compositional difference between the surface and core of the material, diffusion alloys are impossible to mechanically delaminate from their core, unlike tradi- tional laminates.
While aesthetic differences may be
indistinguishable, the material’s reduced scrap rates stand out. In standard oper- ations, ferritic stainless work hardens substantially as it is drawn to form. Work hardening causes problems for OEMs such as springback, die wear, etc., leading to high scrap rates and program costs. The material’s customizable yield strength, high elongation and reportedly outstanding r-bar increases the range of design geome- tries—deeper draws and tighter radii.
Ultra-Thin Gauges
Optiform has been rolled to foil gauges for catalyst, thermal management and membrane support, to name a few current applications. Even as a foil, the mechanical properties, dominated by the ultra-low- carbon core, enable the material to main- tain excellent ductility. This allows for the complex design forms often needed for catalysts and membrane supports to be imparted without tearing, or damaging production tooling. During rerolling to foil gauges, both the alloy layers and core are reduced equally, and both work harden. However, the magnitude of the delta between recrystallization-temperatures for the alloy layers and the substantial recrystallization-temperature of the core region make it is possible to keep the alloy layer work hardened while recrys- tallizing the core alloy (see image).
This unique combination of metallur- gically bonded microstructures imparts a material with high stiffness but excellent
12 MetalForming/March 2019
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