| 摘要 |
<p>1466330 Cast iron grinding members ACIERIES THOME CROMBACK 3 May 1974 [4 May 1973] 19565/74 Heading C7A Grinding members are made from white cast iron of composition: by beating a bar of white cast iron to a temperature in the range 1,000 to 1120‹C, cutting the bar into pieces at this temperature, forging the pieces at a temperature of 1,000 to 1,070 C which is equal to or lower than the first temperature and hardening the forged pieces to obtain a solid martensitic or austenitic matrix containing chromium exclusively of the M 7 C 3 type. Alternatively pieces of white iron may be used instead of the bar of white iron and the bar cutting operation may be dispensed with. The forged pieces may be subjected to an isothermal heat-treatment e.g. 15 minutes at a temperature in the range 970 to 990‹C prior to hardening in oil or air and the hardened forged pieces obtained may be subsequently tempered e.g. at 250‹C. An additional annealing treatment between the isothermal treatment and hardening step may be employed and the resulting grinding members which may be in the form of grinding balls may be utilized in the cement industry.</p> |
