| 摘要 |
1292723 Making bearing components; working at specified temperatures FORD MOTOR CO Ltd 11 May 1970 [9 June 1969] 22623/70 Headings B3A and B3V [Also in Division C7] The subject-matter of this Specification is similar to that described in Specification 22622/70 except that the spheroidization anneal produces carbides of 2-5 microns diameter. The spheroidizing anneal comprises heating the forgings in nitrogen just below the austenite forming temperature at 1380‹ F. for 3 hrs., after which the temperature is raised above the austenite forming temperature to 1420‹ F. so that austenite coexists with carbides. After 3 hrs. the temperature is lowered to 1380‹ F. and after annealing times of 3 hrs. the temperature is lowered in 20‹ F. intervals down to 1260‹ F. The carbon is thereby precipitated on the existing undissolved carbides. The tempering temperature may be 250-400‹ F. |
