| 摘要 |
One of the difficulties in developing a metallic material which is corrosion resistant to caustic alkaline solutions is that the corrosiveness of these solutions is different depending upon the process for producing the same. The chromium alloyed steel developed according to the present invention, contains, from 29 to 31%, of Cr; not more than 3% of Mo; not more than 0.005% of C; at least one element selected from the group of Nb and Ta in an amount, which follows the equation 20xC(%)</=Nb(%)+0.5xTa(%)</=60xC(%); from 0.0005 to 0.02% of Ca and; not more than 0.02% of deoxidation products being present in said chromium alloyed steel and essentially composed of CaO, SiO2 and Al2O3. Because of the combination of the reduction of C, N and the impurities of the steel with the addition of Nb and/or Ta, the corrosion resistance of the chromium steel is excellent with regard to the caustic alkaline solution produced by every kind of processes. This excellent corrosion resistance is not essentially degraded by the welding of the chromium steel pieces and, further, the ductility and workability of the chromium steel are improved.
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