我厂生产的三轮压路机缸体,其机械性能、组织致密度、加工光洁度等要求较高。总装前须经30公斤/厘米~2水压试验。过去缸体用HT20—40制造。由于普通灰铸铁石墨粗大,组织不致密,硬度较低。机械加工后内表面A处常发现缩松及石墨剥落,光洁度达不到▽7,水压试验时产生渗漏而报废。废品率有时高达50～60％。 I plant production of three roller roller block, the mechanical properties, organizational density, processing and other requirements of higher finish. Assembled by 30 kg / cm ~ 2 hydrostatic test. In the past, the cylinder was made of HT20-40. As a result of ordinary gray cast iron coarse, the organization is not dense, lower hardness. Mechanical processing often found on the inner surface of A shrinkage and graphite spalling, finish less than ▽ 7, hydraulic test leaks and scrapped. Scrap rate sometimes up to 50 to 60%.