奥-贝球铁焊缝金属的连续冷却转变图及其组织分析

CCT Diagram of Austenitic-bainitic Ductile Iron Weld Metal and Microstructure Analysis of Weld

为了研究焊态下奥－贝球铁焊缝在不同冷速下的组织变化及其相变规律，本文采用Ｆｏｒｍａｓｔｏｒ—Ｆ相变分析仪测定了在不同冷速下焊缝金属的膨胀量曲线，然后通过对曲线特征进行分析，并结合金相组织定量分析及硬度分析等方法，找到了在各冷速下的相变临界点，最终建立了奥－贝球铁焊缝的连续冷却转变图（ＣＣＴ图）。为选择焊接工艺提供了科学的基础。

In order to study the microstructure change and the phase transformation of the austenitic～bainitic ductile iron weld metal , a Formastor ～F phase transformation apparatus has been used to measure the cooling curves and volume expansion curves of the weld under different cooling rate. Through analyzing the characterization of these curves and in combination with the data obtained from the quantitative metallographic analysis and hardness measurement , all the critical points of the phase transformation were determined and a continuous cooling transformation diagram (CCT diagram)of the weld metal was developed . The diagram will be used to help the choice of the welding technology .