Bio-co-cr-mo alloy with ion elution suppressed by structure control, and process for producing same

Abstract

This invention provides a technique for rendering bio-toxicity such as allergy toxicity derived from Ni trace impurity, i.e., nickel toxicity, which is unavoidably present in a bio-Co—Cr—Mo alloy or an Ni-free stainless steel alloy unharmful, characterized in that an element selected from the group consisting of the group 4, 5 and 13 elements of the periodic table, particularly an element selected from the group consisting of the group 4 elements of the periodic table, is added to the alloy composition. The additive element is preferably an element selected from the group consisting of zirconium and titanium, more preferably zirconium.

1 . A method for neutralizing bio-toxicity due to Ni trace impurity in a bio-Co—Cr—Mo alloy or a Ni-free stainless steel alloy; said method characterized by comprising adding an element or compound selected from the group that consisting of an element of groups 4, 5, and 13 of the periodic table, an lanthanide element, a misch metal, and Mg to an alloy composition. 
     
     
         2 . The method for neutralizing nickel toxicity according to  claim 1 , characterized in that the additive element is selected from the group consisting of Zr, Hf, Ta, B, Mg, Al, Ti, Zr, and Nb. 
     
     
         3 . The method for neutralizing nickel toxicity according to  claim 1 , characterized in that an element selected from the group consisting of an element of group 4 of the periodic table is added to an alloy composition. 
     
     
         4 . The method for neutralizing nickel toxicity according to  claim 3 , characterized in that the additive element is selected from zirconium and titanium. 
     
     
         5 . The method for neutralizing nickel toxicity according to  claim 3 , characterized in that the additive element is zirconium. 
     
     
         6 . The method for neutralizing nickel toxicity according to  claim 1 , characterized in that
 a nickel content in the alloy composition is (1) about 1.0 wt % or less, (2) about 0.5 wt % or less, (3) about 0.002 wt % or less, (4) at least on the order of 100 ppm or less, or (5) on the order of several hundred parts per million or less; and   the alloy composition is an alloy in which Ni is unavoidably present.   
     
     
         7 . The method for neutralizing nickel toxicity in a bio-Co—Cr—Mo alloy or a Ni-free stainless steel alloy according to  claim 1 , characterized in performing heat treatment at a temperature of 600° C. to 1250° C. after alloy melting. 
     
     
         8 - 28 . (canceled) 
     
     
         29 . The method for neutralizing nickel toxicity in a bio-Co—Cr—Mo alloy or a Ni-free stainless steel alloy according to  claim 2 , characterized in performing heat treatment at a temperature of 600° C. to 1250° C. after alloy melting. 
     
     
         30 . The method for neutralizing nickel toxicity in a bio-Co—Cr—Mo alloy or a Ni-free stainless steel alloy according to  claim 3 , characterized in performing heat treatment at a temperature of 600° C. to 1250° C. after alloy melting. 
     
     
         31 . The method for neutralizing nickel toxicity in a bio-Co—Cr—Mo alloy or a Ni-free stainless steel alloy according to  claim 4 , characterized in performing heat treatment at a temperature of 600° C. to 1250° C. after alloy melting. 
     
     
         32 . The method for neutralizing nickel toxicity in a bio-Co—Cr—Mo alloy or a Ni-free stainless steel alloy according to  claim 5 , characterized in performing heat treatment at a temperature of 600° C. to 1250° C. after alloy melting. 
     
     
         33 . The method for neutralizing nickel toxicity in a bio-Co—Cr—Mo alloy or a Ni-free stainless steel alloy according to  claim 6 , characterized in performing heat treatment at a temperature of 600° C. to 1250° C. after alloy melting.