汽车底盘零部件用非调质冷镦钢开发与应用

Development and Application of Non-Quenched and Tempered Cold Heading Steel for Automobile Chassis Parts

采用Thermo-Calc软件进行成分设计,结合连续冷却转变(CCT)曲线制定控温-控轧-控冷工艺。通过降低电炉出钢氧含量、优化炉外精炼软吹工艺、采用保护浇铸措施,可实现热轧盘条A类夹杂物≤1.0级,B类夹杂物≤0.5级,C类夹杂物0级,D类细系夹杂物≤1.0级,Ds夹杂物0级;通过控温-控轧-控冷工艺,可获得铁素体+珠光体组织,抗拉强度≥740 MPa,延伸率≥22%,面缩率≥52%,总脱碳层深≤0.10 mm,晶粒度≥9级,冷顶锻满足1/3不开裂。结果表明:开发的非调质冷镦钢经拉拔后可同时用于制作转向球销、10.9级螺栓以及刹车系统导杆等汽车底盘零部件。

In this paper,Thermo-Calc software was used for composition design,and the temperature control rolling control cooling process was formulated in combination with the Continuous Cooling Transformation(CCT)curve measured by thermal simulation.By reducing the oxygen content of electric furnace tapping,optimizing the soft blowing process of external refining and adopting protective casting measures,type A inclusion level of hot rolled wire rod≤1.0,type B inclusion level≤0.5,type C inclusion level=0,and type D inclusion level≤1.0,type Ds inclusion level=0.Ferrite-pearlite microstructure can be obtained by controlled rolling,temperature and cooling process,with tensile strength≥740 MPa,elongation≥22%,surface shrinkage≥52%,total decarburization depth≤0.10 mm,grain size level≥9 and cold forging meeting 1/3 of the requirements without cracking.The results indicate that the non quenched and tempered cold heading steel developed in this research can be simultaneously used to make automotive chassis components such as steering ball pins,Grade 10.9 bolts,and brake system guide rods.