Alloy 800H Beams for High Temperature Furnace Support
A chemical and pharmaceutical company needed a beam to support a chemical container inside a heat treatment furnace running continuously at 600 degrees Celsius. At that temperature a structural section is no longer selected on corrosion resistance alone, because the alloy has to retain its mechanical properties under sustained thermal load, and the production route has to leave those properties intact. Montanstahl identified Alloy 800H as the material best suited to the environment and produced the sections by hybrid laser welding, delivering custom sized beams of 70×60 mm and 63.5×60 mm with 8 mm flange thickness, cut to length in twelve different sizes.
A Structural Support Working Inside a Heat Treatment Furnace
In chemical and pharmaceutical production, stainless steel is often indispensable. Hygiene requirements, corrosion resistance, durability and ease of cleaning tend to point to the same family of materials, and that versatility is the reason why stainless grades dominate equipment design across the petrochemical, chemical and pharmaceutical sector. The component requested here was a beam acting as a support for a chemical container placed inside a furnace. The furnace is used for heat treatment and runs at a constant temperature of 600 degrees Celsius, which changes the nature of the specification entirely. A support of this kind is loaded permanently while it sits at temperature, so the relevant question is not how the material behaves in a short excursion but how it behaves after thousands of hours in the same thermal condition. Standard austenitic grades commonly used elsewhere in the plant lose strength progressively in that range and become vulnerable to creep, which is why the selection had to move towards a high temperature alloy.
Three Requirements That Had to Be Satisfied Together
The customer was looking for an alloy that resists corrosion and holds its mechanical properties at constant service temperatures between 500 and 700 degrees Celsius. On top of that came a second condition that is easy to overlook: the manufacturing technology used to build the section must not alter the properties of the chosen material, since an alloy selected for high temperature performance is worth little if the joining process degrades it locally. The third requirement was dimensional. The customer needed custom sizes of a standard beam shape rather than a catalogue section, with a 70 mm overall height, 26 mm flange width, 8 mm flange thickness and angles held within 1.5 degrees, so the beam would fit the geometry available inside the furnace. Combining the three conditions rules out most conventional routes, because arc welding introduces enough heat into a thin flange to modify the microstructure in the joint area, and rolling a custom size in a high temperature alloy is rarely viable for a limited quantity.
Application Context
The technical team identified Alloy 800H as the grade best suited to this environment, thanks to its combination of corrosion resistance and stability at high service temperatures. The production question was solved after several tests with hybrid laser welding, where an arc welding source works together with the laser to reduce heat input, control distortion and bridge the joining gap between the plates, so that the mechanical properties of the starting material are preserved in the finished beam. Montanstahl delivered beams of 70×60 mm and 63.5×60 mm with 8 mm flanges, cut to length in twelve different sizes. The same approach applies whenever a project needs a beam in a dimension that no rolling programme covers, or in an alloy that conventional joining would compromise. Further background on heat input and weld quality is available in our article on the advantages of laser welding, and specific questions are addressed in the Montanstahl technical Q&A.