| 摘要 |
A superplastic hot working method for a duplex-phase, nitrogen-containing ferrous alloy and stainless steel, and a superplastic duplex-phase ferrous alloy are disclosed. The ferrous alloy comprises: at least one of Si and Mn in an amount of not less than 0.5 % and not less than 1.7%, respectively; and N: at least 0.01% in solid solution, wherein Si eq and Mn eq which are defined as: Si eq=Si+(2/3) (Cr+Mo), and Mn eq=Mn+2Ni+60C+50N, satisfy the formula: (5/6) (Si eq)-15/2</=Mn eq</=(11/5)(Si eq)-77/5, and its superplastic hot working is carried out by deforming the alloy heated to 700 DEG -1200 DEG C. at a strain rate of 1x10-6 S-1 to 1x100 S-1. In another aspect, superplastic hot working of a duplex-phase stainless steel comprising Cr: 10.0-35.0%, Ni: 2.0-18.0%; Mo: 0-6.0%, and N: 0.005-0.3% and having the values of Si eq and Mn eq as above is carried out by deforming the steel at a strain rate of from 1x10-6 S-1 to 1x101 S-1 after heating to a temperature of at least 700 DEG C. and at most 100 DEG C. below the temperature at which the steel transforms into a single ferrite phase, preferably in a non-oxidizing nitrogen atmosphere. |
