白口铸铁焊接热敏感性的研究

STUDY ON WELDING HEAT-SUSCEPTIBILITY OF WHITE CAST IRON

采用焊接热模拟技术再现了白口铸铁焊接热影响区(HAZ)的组织,研究了热循环的改变对焊接热影响区的组织和冲击韧性的影响以及焊接断口的特征。试验结果表明,经受焊接热循环作用后,白口铸铁的冲击韧性下降。经高峰温热循环作用后,白口铸铁的组织主要为渗碳体加孪晶马氏体,其硬度高,冲击韧性较好;峰温800℃时,组织硬度最低,冲击韧性最差,再经过高峰温热循环的作用,组织硬度提高,冲击韧性得以改善。

Weld thermal sycle simulation technique was used to reveal the structures of the heat Effected zone(HAZ).The influence of the change of thermal cycles on the structure and impact toughness of HAZ in the welding process was investigated.The fracture of impacted specimens was observed with SEM.The test results showed that the impact toughness of white cast iron decreased under the influence of thermal cycles.As the result of thermal cycles,the structral components of white cast iron became cementite plus twin martensite with high hardness and high impact toughness.At a peak temperature of 800℃.the impact toughness and hardness of white cast iron were lowest.If white cast iron reheated at a higher peak temperature,the impact toughness and hardness of HAZ may be improved.