高冲击韧性QT900-6材料的开发与应用

Development and Application of QT900-6 with High Impact Toughness

通过优化球墨铸铁材料微量元素配比,采用SiC基变质剂进行铁液预处理和分段保温热处理的方式,研发出高冲击韧性的QT900-6新型球墨铸铁材料。该材料组织中石墨球数量明显增加,铁素体呈分散的破碎状分布,Si在铁素体中的固溶量减少,珠光体团和片间距明显变小,综合作用提高了材料的韧性。材料抗拉强度达到956 MPa,伸长率达到7.4%,缺口冲击吸收功达到5.2 J,而且仍保留着低塑性材料的可胀断优势。利用该QT900-6材料生产的球墨铸铁胀断连杆具有胀断性好、疲劳强度高、重量一致性好的优点,成本比锻钢连杆低,各项指标能够满足发动机连杆节能、降耗、降成本、高可靠性的要求。

A new type of ductile iron(QT900-6)with high impact toughness was developed by optimizing the proportion of trace elements in ductile iron material,using silicon carbide based modifier for pretreatment,and segmented thermal insulation heat treatment.The number of graphite spheres in the microstructure of the material increased obviously,ferrite was distributed in a dispersed and broken shape,the solid solution of Si in ferrite decreased,and the spacing between pearlite clusters and sheets decreased obviously.The comprehensive effect improved the toughness of the material.The tensile strength of the material reached 956 MPa,the elongation reached 7.4%,the notch impact energy reached 5.2 J.Moreover,it still retained the advantage of low plastic material which can be fractured.The ductile iron fracture split con-rod produced by QT900-6 material has the advantages of good fracture property,high fatigue strength and good weight consistency.The cost is lower than that of forged steel con-rod.The indexes can meet the requirements of energy saving,consumption reduction,cost reduction and high reliability of the engine con-rod.