根据国外产品实样,GM(轧兰姆林)汽缸套是用镍铬合金铸铁铸成,其中有的是用砂型铸造的,也有的是用离心铸造的。我厂根据用户要求改用—55牌号球墨铸铁铸造。它的化学成分是:碳2.6～3.8％,硅2.5～2.85％,锰0.7％左右,磷0.08～0.1％,硫0.008％左右,金相基体组织要求是珠光体,铁素体少于5％,不允许有游离碳化铁存在。铸件(如图1)加工后上部需经70公斤/公分~2水压试 According to the actual situation of foreign products, GM (roll Lam Lam) cylinder liner is made of nickel-chromium alloy cast iron, of which some are sand cast, and some are by centrifugal casting. I plant according to user requirements switch to -55 grade ductile iron casting. Its chemical composition is: 2.6 ~ 3.8% of carbon, 2.5 ~ 2.85% of silicon, 0.7% of manganese, 0.08 ~ 0.1% of phosphorus and 0.008% of sulfur. The microstructure of matrix requires pearlite with ferrite less than 5% , Does not allow the existence of free iron carbide. Casting (Figure 1) After processing the top by 70 kg / cm ~ 2 water pressure test