I’ve been pointing people at this for a while. Expensive? Not “just” steel though is it:
“Fully fillet brazed Columbus 29R niobium tubes” as follows:
“NIOBIUM
It’s a special micro alloyed steel with Manganese, Chrome, Nickel, Molybdenum and Niobium. In the Columbus research and development tradition it can be considered the evolution from of the Thermacrom and Nivacrom alloy. It’s designed to provide better mechanical properties and greater resistance to atmospheric corrosion than conventional carbon steels. For every top-of-the-line and competition frames where lightness and high reliability are fundamental. Like Vanadium in Thermacrom steel, Niobium increases yield strength by precipitation hardening and acts for refinement of grain size. Thanks to the special Columbus chemical composition, the combined effect of precipitation strengthening, and grain refinement the properties are incredibly increased inith respect. To standard steels. Niobium is a more effective strengthening agent than Vanadium. After mechanical deformation working and drawing, NIOBIUM undergoes a special heat treatment that gives the steel its final characteristics; this heat treatment is designed to minimize the tubes distortion and decarbonization phenomena. Columbus heat treatment results in a super fine high-strength microstructure of bainite, wich means high strength, hardness and long fatigue life.
Mechanical characteristics:
Ultimate tensile strength = 1050 ÷ 1250 MPa
Yeld strength: min 750 MPa
Minimum elongation: 14%”
Pretty special, and pretty exclusive.