铸铁由于具有良好的物理和力学性能、优异的铸造性能及低廉的成本等优点，是用量最多的铸造金属材料。高温场合是铸铁的一个重要应用领域，例如汽车制动盘、发动机的缸体和缸盖、钢锭模等铸件。由于这些产品的工作温度高，并且需要承受热循环载荷，不仅要求铸铁具有高的力学性能，还要求高的导热性能。然而，铸铁的力学性能强化方法往往会降低其导热性能。导热系数是决定上述产品使用寿命的关键性能指标。因此，在满足力学性能要求的前提下，新型高导热铸铁的设计与开发具有迫切的工程应用需求。研究铸铁的导热性能与成分、组织及温度的关系，是研发这类高导热铸铁新材料的基础，其具有重要的学术价值。灰铸铁和球墨铸铁的组织都由基体和不同类型石墨组成，可看作自生复合材料。因此，借鉴复合材料理论，铸铁的导热系数不仅取决于石墨，还取决于基体，而基体主要的组成相为铁素体。基于此，本文通过金属热传导理论建立了铁素体的导热系数与合金元素和温度的关系模型，并根据该模型研究了合金元素和温度对铁素体导热系数的影响规律。所有合金元素的溶入都会降低铁素体的导热系数，但不同元素的影响程度不同，其中Si的影响最强烈。随着合金元素含量的增加，铁素体的导热系数随温度变化的规律会由单调递减逐渐转变为先增大后减小最后为单调递增。从而导致铸铁的导热性能随温度的变化也呈现类似的规律。针对灰铸铁中石墨导热系数存在强烈的各向异性和共晶团内石墨呈花瓣状连通的结构形态特点，建立了灰铸铁导热的单元体模型。共晶团内石墨局部连通的结构会明显提高灰铸铁整体的导热性能。并且石墨含量越高，石墨厚长比越小，连通效应对整体导热系数的提升越显著。基于有效介质理论，建立了球墨铸铁的导热模型。相比于石墨含量和珠光体分数等组织参数，球墨铸铁的导热系数对Si含量更敏感，Si含量的调控是设计和开发高导热球墨铸铁的关键。打破了球墨铸铁导热系数低、不适合制备耐热零部件的传统认知，基于铸铁导热性能的理论研究结果，设计了新的球墨铸铁成分范围和优化组织，研发出了一类超高导热超高韧性球墨铸铁。其导热系数在27-300℃超过40W/m K，并且至500℃仍能维持35W/m K以上，延伸率超过25%，抗拉强度超过300MPa。由于这类球墨铸铁的室温导热系数接近普通灰铸铁，并且在较高的温度下基本保持不变，加上球墨铸铁本身所具备的高韧性和高强度优势，其有望成为一个高导热高韧性球墨铸铁新品种，应用在钢锭模等需要承受热循环应力的产品上。

Cast irons are among the most widely used casting alloys due to their great physical and mechanical properties, excellent casting ability and low cost. Some cast iron products used in heat resistant applications endure cycle impacts of high temperature under bad service conditions, such as brake discs, engine blocks and cylinder heads, ingot moulds. Hence these products require not only high mechanical properties, but also high thermal conductivity. However, the relationship between mechanical properties and thermal conductivity is always opposite. The thermal conductivity of these above products is a crucial property to determine service life. Therefore, under the premise of basic mechanical properties, there is an urgent engineering application demand for the design and development of high thermal conductivity cast irons. In order to obtain these new cast irons, it needs to be cleared the relationship between the thermal conductivity of cast iron and its composition, microstructure and temperature. These studies also exert great academic significance.The microstructure of gray cast iron and nodular cast iron is composed of matrix and different types of graphite. Referring to the theory of composite materials, the thermal conductivity of cast iron depends not only on that of graphite, but also on that of matrix. Because ferrite is the main constituent of matrix, in this paper, a thermal conductivity model of ferrite is established based on the theory of metal heat conduction. And according to this model, effects of alloying elements and temperature on the thermal conductivity of ferrite are studied. Calculated results show that all alloying elements decrease the thermal conductivity of ferrite. However, the influence of different element is different, and the effect of Si is the strongest. With the addition of alloying elements, the relationship between the thermal conductivity of ferrite and temperature changes from monotonic decreasing to increasing first and then decreasing and to finally monotonic increasing. This is the key reason for the similar temperature dependence of cast iron thermal conductivity.A theoretical model of gray cast iron with interconnected graphite structure is designed. Then, the corresponding effective thermal conductivity is calculated based on the unit cell model. It is shown that the interconnected graphite structure in eutectic cell significantly enhances the overall thermal conductivity. Moreover, higher content and smaller aspect ratio of flake graphite will make the connectivity effect of graphite more obvious to improve the overall thermal conductivity. Based on the effective medium theory, a model for nodular cast iron is built. Compared with the volume fraction of pearlite and graphite, the thermal conductivity of nodular cast iron is more sensitive to Si content. Therefore, the main method to design and develop high thermal conductivity nodular cast iron is to control the content of alloying elements, especially for the Si content.For nodular cast iron, low thermal conductivity limits its use in heat resistant applications. We broke the common composition range of nodular cast iron, designed a new composition range and optimized microstructure. New nodular cast irons with super-high thermal conductivity and elongation were prepared. Their thermal conductivity exceeded 40W/m K within 27~300℃, and maintained above 35W/m K at 500℃. The elongation was over 25%, and the tensile strength was more than 300 MPa. Because the thermal conductivity of nodular cast iron is obviously improved, excellent elongation and strength in combination with high thermal conductivity at elevated temperature make them become the more preferred materials to endure thermal cycle compared with gray cast iron. They are expected to become a new type of nodular cast irons with high thermal conductivity and elongation, which may be suitable for ingot moulds and other products under thermal-mechanical cycling.