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采用水平连续铸造工艺并加入Ti与Sb微合金化,制备了准220 mm大直径高强度灰铁型材,分析了该型材不同部位的组织与性能。结果表明,该灰铁型材以D型石墨为主,心部有少量A型或E型石墨,基体为铁素体和珠光体混合型,表层珠光体含量接近40%、1/2R处珠光体含量接近80%、心部珠光体85%~95%。水平连铸过程高的冷却速度、微合金化、良好的补缩是获得无缺陷、高强度、高共晶团数量灰铁型材的基础。拉伸性能指标高于HT/LZ350牌号水平,断面均匀性好,硬度差小于10 HRB。耐压气密性与其强度指标密切相关,耐压气密性试样爆破前均未发现点渗和周渗现象,爆破强度均在50 MPa以上。
Horizontal continuous casting process was adopted and Ti and Sb microalloyed were added to prepare quasi-220 mm high-strength, high-strength gray iron profiles. The microstructure and properties of the profiles were analyzed. The results show that the gray iron is mainly composed of D-type graphite with a small amount of A-type or E-type graphite in the core. The matrix is a mixture of ferrite and pearlite with the pearlite content close to 40%. The pearlite at 1 / 2R The content is close to 80%, heart pearl 85% ~ 95%. Horizontal high-speed casting process cooling rate, micro-alloying, good shrinkage is to obtain defect-free, high strength, high eutectic volume gray iron profiles. Tensile performance index higher than HT / LZ350 grade level, good cross-section uniformity, hardness difference less than 10 HRB. Pressure tightness is closely related to its strength index. Before pressure blasting, no infiltration and percolation phenomena were observed, and the burst strength was above 50 MPa.