| 摘要 |
1350831 Making plates and tubesaltering physical structure SANDVIK AB 18 June 1971 [30 June 1970] 28776/71 Headings B3A and B3V [Also in Division C7] Austenitic stainless steel covered on one or both sides with ferritic stainless steel is heat treated, cold worked and finally heat treated to recrystallise only the ferritic steel so as to produce a high temperature resistant composite. A strip, plate or tube, e.g. for a heat exchange unit, is made by first quenching a composite blank from above 1000‹ C., e.g. 1030-1230‹ C. and cold working it by drawing, rolling and/or bending. The cross-sectional area of the blank may be reduced by 5-70%. The composite is finally heat treated at 650-950‹ C. to recrystallize only the ferritic steel to a grain size of 300-600 Á<SP>2</SP>. In one example, the austenitic stainless steel comprises 0À03-0À20% C, 1% max Si, 0À2-3% Mn, 14-20% Cr, 12À5-35% Ni, 0À3-0À8% Ti, 0À2-1À7% Mo, 0À002- 0À020% B, 0À5% max V, W, Nb and/or Ta, 1% max Co, 0À5% max Cu, 0À2% max Ce and/or Zr and the ferritic stainless steel comprises 0À03-0À10% C, 10-14% Cr, 1% max Si, 1% max Mn, 1% max Ti, 1À5% max Tu and/or Nb, 3% max Al. |
