退火温度对球墨铸铁的组织与力学性能的影响

Effect of Annealing Temperature on Microstructure and Mechanical Properties of Nodular Cast Iron

利用某铸造企业单铸的圆柱形试棒进行不同温度下的退火实验,检测分析了退火温度对球墨铸铁的组织和力学性能的影响。结果表明:退火温度越高,渗碳体溶解越快,粒状渗碳体越多。在710~750℃范围内,随着退火温度的升高,试样的抗拉强度会降低,延伸率会升高。与铸态试样相比,在退火温度相对较低的710℃时,因微量碳原子固溶强化作用,碳原子在石墨上的沉积以及石墨化过程中体积膨胀,增强了石墨与基体的结合强度,退火态试样的抗拉强度增加了6%,而渗碳体的球化使得其延伸率也略有增加。在退火温度为710℃时,试样可获得相对最佳的力学性能。

The effect of annealing temperature on the microstructure and mechanical properties of nodular cast iron is detected and analyzed by using the single cast cylindrical bar of a foundry enterprise to carry out annealing experiments at different temperatures.The results show that the higher the annealing temperature is,the faster the dissolution of cementite is and the more granular cementite is.In the range of 710℃to 750℃,the tensile strength of the sample decreases and the elongation increases with the increase of annealing temperature.Compared with the as-cast sample,the bonding strength between graphite and matrix is enhanced due to the solid solution strengthening of trace carbon atoms,the deposition of carbon atoms on graphite and the volume expansion during graphitization at a relatively low annealing temperature of 710℃.The tensile strength of the annealed sample increased by 6%,and the elongation of the cementite increased slightly due to the spheroidization of the cementite.The best mechanical properties can be obtained when the annealing temperature is 710℃.