【摘要】 工业水平的发展对低合金低碳钢的性能提出了更高的要求。较高的强度、良好的韧性和抗疲劳能力以及优异的耐蚀性等是低合金高强钢开发的主要方向。微合金化处理通过在钢中加入微量的合金元素可以明显地改善材料的性能。钛微合金化成本较低,能够明显细化奥氏体晶粒,提高材料的强度,具有广泛的应用价值。微合金化元素钛与钢中的碳元素、氮元素反应生成的Ti N、Ti C以及Ti(C,N)第二相粒子所产生的沉淀强化、细晶强化等作用能够明显改善材料的性能。Ti N粒子析出温度较高,细小的Ti N粒子可以抑制高温下晶粒的长大;而粗大的Ti N粒子对材料的性能不利。Ti C粒子可以在铁素体基体中随机沉淀析出,并与基体保持一定的位相关系,还可以钉扎位错、细化晶粒。Ti(C,N)粒子由Ti C与Ti N互溶形成,可以钉扎位错,产生析出强化。第二相粒子的尺寸受热处理工艺等影响,因此,需要严格调控材料的热处理工艺,避免粗大第二相粒子的形成。钛的微合金化作用还受到钢中其他合金元素的影响,钛与钼、锰、硼等元素可以产生协同作用,相互促进,有利于材料的强韧性匹配。将钛元素与铌元素、钒元素中的一种或两种同时引入合金钢中进行复合微合金化处理,钛铌复合可以在提高材料强度的同时避免塑性的大量损失,钛钒复合可以降低强度提高时对材料韧性的损害并有效提高材料的淬透性,铌钒钛复合可以结合三种元素的优点更好地改善材料的性能。但是,复合微合金化对合金元素含量具有较高的要求,含量控制不当会严重影响材料的性能。文中主要介绍了近年来国内外关于低碳钢的钛微合金化的研究现状,并针对微合金化的强韧化机理研究进展进行了分析和评述,以期为制备性能优良、适合实际生产的微合金化钢提供参考。更多还原

【Abstract】 Acombination of high strength,good toughness,fatigue resistance and excellent corrosion resistance is required for developing new microalloyed low carbon steels. Microalloying treatment is one of most effective methods,in which small amount of alloying elements,such as Nb,V or Ti can improve the performance of steels significantly. The microalloying element Ti can react with carbon and nitrogen in the steel forming Ti N,Ti C and Ti( C,N) particles. These particles play important roles in precipitation strengthening,grain refinement strengthening and some other effects.The precipitation temperature of Ti N particles is high,and the fine Ti N particles can inhibit the growth of the grains at high temperature,specifically the growth of prior austenite. Ti C particles can be randomly precipitated in the ferrite matrix and maintain a certain crystal relationship with the matrix. Ti( C,N) particles are composed of Ti C and Ti N,which can pin dislocations and contribute to the precipitation strengthening. The size,morphology and distribution of these particles are influenced by the heat treatment process and composition. Therefore,the content of Ti and the heat treatment should be controlled carefully to avoid the formation of coarse second phase particles. The effects of microalloying Ti can also be influenced by other alloying elements in steels,such as molybdenum,manganese,boron and other elements. These alloying elements can affect each other,forming the synergistic effects,which can be applied to improve both strength and toughness. Ti can also be alloyed with Nb or V or both. Alloying of Ti and Nb together can improve the strength of the material without a large loss of plasticity. While Ti and V combination can improve the strength without sacrificing the toughness of the steels. However,it should be noted that the content of microalloying elements should be controlled carefully to avoid deteriorating the performance.This paper mainly introduces the current research status on the microalloying of Ti in low carbon steels. The strengthening and toughening mechanisms of the microalloying are also reviewed and discussed. These may provide some insights in designing and producing microalloyed steels with excellent performance.更多还原