| 摘要 |
A steel containing 0.15-0.25 wt % carbon, 1-2% manganese, 1-2.5% aluminium and less than 0.5% silicon, 0.03% phosphorous, 0.01% sulphur, 0.03% titanium and 0.009% nitrogen is formed into a band by rolling at below 880 deg C, followed by cooling in air for less than 10 secs., then further cooling controlled at between 20 and 100 deg C/sec, depending on the band thickness, down to a temperature below that of transformation of austenite to ferrite (eg 700-750 deg C). The band is again cooled in air at 3-10 deg C/sec down to 640-700 deg C and finally subjected to controlled cooling at 20-100 deg C/sec, depending on band thickness, down to 300-450 deg C. Also claimed is a sheet of the aforesaid steel which has been so hot-rolled and cooled. |
