Every time you run your vacuum furnace, it has to heat and cool whatever you put in it. When you use HAYNES® high-temperature alloys for all of your baskets and fixturing, what you don’t put in the furnace is unnecessary weight. HAYNES HR-120® and 230® alloys not only provide superior performance compared to traditional heat treating fixture materials, they do it with thinner section thickness construction. This allows you to save three ways: (1) reduced heating and cooling cycle times, (2) reduced part rejection from poor quench rate, and (3) increased furnace load capability without increased cycle time or reduced quench rate. Compare the sizes of these alloys required for field-proven equivalent or superior performance relative to traditional materials:
Resistance to sagging or distortion of vacuum furnace baskets and fixtures at elevated temperatures is directly related to the creep or stress rupture strength of the material of construction. Both 230 and HR-120 alloys exhibit large strength advantages over traditional alloys. This allows for either higher loading capability, or significant reduction in the basket or fixture section thickness.
*Also known as Columbium
Two baskets were constructed to a 33-inch x 46.5 inch (840mm x 1180 mm x 200 mm) design. One basket was fabricated using 230 alloy plate and round bar with section thicknesses ranging from 1/4-inch to 7/16-inch (6.3 mm to 11.1 mm). The alloy 601 basket was built with section thicknesses ranging from 1/2-inch to 5/8-inch (12.7 mm to 15.9 mm). As fabricated, the alloy 601 basket weighed 111 pounds (50.5 Kg), while the basket made from 230 alloy weighed 63 pounds (28.6 Kg), a 43% weight reduction.
Both baskets were placed in vacuum furnace service to assess the differences in resisting distortion, and to determine the effects of the 230 alloy lightweight construction upon furnace cycle time and quench rate. The condition of the baskets after 250 furnace exposures between 1600 and 1900ºF (870 and 925ºC) is shown in the photograph below.
Even after this relatively short use time, the superior distortion resistance of the 230 alloy basket was evident. The effect of the lightweight construction of the 230 alloy basket was also quite evident in both cycle time and quench rate measurements under various load conditions. Quench cycles consisted of forced nitrogen cooling to 400ºF (205ºC) and then open furnace air cooling to ambient. Results show an average improvement of about 20% in quench time and about 18% quench rate.
While stress rupture strength is a key design criteria for building baskets, grids, and fixtures that are resistant to sagging, high-temperature yield strength is important for these components to resist distortion from thermal stresses that arise during heating and cooling. HAYNES 230 and HR-120 alloys possess significant high-temperature yield strength advantages over traditional alloys, without sacrificing important tensile ductility.