热处理温度对E71T-1C熔敷金属力学性能和组织的影响

Effect of the annealing temperature on the mechanical properties and microstructure of deposited weld metal with E71T-1C flux cored wire

对核电工程用药芯焊丝E71T-1C焊丝进行焊接实验,将熔敷金属试样分别进行480℃、550℃、620℃、690℃、760℃保温16 h热处理。利用金相显微镜、材料试验机、冲击试验机、扫描电镜等对试样进行分析与测量,结果表明:熔敷金属经过不高于690℃热处理后,显微组织为铁素体+细粒珠光体+第二相。热处理温度达到760℃后,熔敷金属发生相变,铁素体形貌变为块状,显微组织为铁素体+少量珠光体+第二相。随着热处理温度的升高,析出相不断在晶界成核并长大,-20℃冲击韧性值逐渐降低。当热处理温度升高至690℃时,冲击值最低,降低至95 J。所有熔敷金属断口样品的宏观形貌和微观形貌都呈现出典型的冲击断口形貌特征,冲击性能良好。

Welding experiment on flux cored wire E71T-1C for nuclear power engineering were carried out and then the deposited metal were subjected to post-weld heat treatment(PWHT),which were annealed at 480℃、550℃、620℃、690℃、760℃for 16 hours.Optical microscope,material testing machine,impact testing machine and scanning electron microscope were used here.It is shown that,the microstructure is composed of ferrite,fine ferrite and second phase after the specimen is annealed below 690℃.When the annealing temperature reaches 760℃,the microstructure consists of blocky ferrite and a small amount of pearlite coupled with second phase.As the temperature increase,the precipitates nucleate and grow at grain boundary,in addition,the impact toughness value decreases.When the annealing temperature is raised to 690℃,the impact value tested at-20℃is the lowest,that is,95 J.Typical impact fracture morphology and sound impact properties are illustrated by the macrostructure and microstructure of all deposited metal fracture samples.