ESSENTIALLY NICKEL-FREE STAINLESS IN CANNULATED BAR STOCK FOR IMPLANTABLE ORTHOPEDIC USES
06 February 2003 - Carpenter Technology Corporation

BioDur® 108 alloy (UNS S29108 ASTM F2229), designed to minimize problems associated with nickel toxicity, in cannulated bar form can be considered for bone screws, intramedullary nails for the femur, instruments and any other trauma devices requiring a hole from end to end.

The hole in the cannulated stock allows space for bone marrow to grow, and facilitates the insertion of guide pins for bone screws used in fracture fixation. Cannulated bar also can eliminate or minimize the need for costly drilling operations currently required when using solid bar stock.

BioDur 108 alloy offers corrosion resistance similar to that of nickel-containing 22Cr-13Ni-5Mn alloy (ASTM F1314) at significantly higher strength. The Carpenter alloy has a typical yield strength of 230 ksi (1586MPa) and tensile strength of 250 ksi (1924MPa). Typical values for the 22Cr-13Ni-5MN alloy are 170 ksi (1172MPa) yield strength and 190 ksi (1310MPa) tensile strength.

Despite its higher strength, BioDur 108 alloy has fabricability and ductility similar to that of 22Cr-13Ni-5Mn alloy. BioDur 108 alloy is available in cannulated bar with outside diameters of 0.118-in. (3mm) to 0.750-in. (19mm), with inside diameters of 0.055-in. (1.4mm) to 0.354-in. (9mm). Typical OD dimensional tolerance is ±0.001-in. (+0.025mm), and ID tolerance is ±0.002-in. (+0.05mm).

This alloy has resistance to pitting and crevice corrosion that is superior to Type 316L alloy (ASTM F138) and equivalent to that of 734 alloy (ASTM 1586) which, like 22Cr-13Ni-5Mn alloy, are nickel-containing grades. It is produced by the electro-slag remelting (ESR) process to assure its microstructural integrity and cleanness.

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