以使用高频直缝电阻焊连接的低碳铁素体不锈钢焊管为研究对象，对其进行不同温度的退火处理。通过OM、SEM、TEM和拉伸、冲击实验分别研究退火温度对低碳铁素体不锈钢高频直缝电阻焊接头组织和性能的影响。在高频直缝电阻焊过程中，低碳铁素体不锈钢管的焊缝区被迅速加热至奥氏体相区，较高的温度和压力使奥氏体晶粒粗化并发生畸变，空冷后转变为α-铁素体和马氏体组织。焊缝区硬度高约315 HV，而其在0 ℃下冲击值几乎为0。经950 ℃保温3 min退火处理后，焊缝区中马氏体组织全部分解，形成粒状贝氏体和α-铁素体组织，使其硬度降至约260 HV，同时将其在0 ℃下的冲击功从0 J提高至约23 J。

With the development of economy and technology, the application of ferritic stainless steel is becoming increasingly wider. 12Cr ferritic stainless steel has low carbon equivalent and good weldability, and it can not only be applied to a variety of conditions, but also reduce the production cost. High frequency longitudinal resistance welding is an advanced welding technology with high quality and efficiency. In this work, low-carbon ferritic stainless steel pipe has been joined successfully by high frequency longitudinal resistance welding. Microstructure characteristics and mechanical properties of the stainless steel pipe joint after annealing at different temperatures for 3 min were investigated by OM, SEM, TEM and mechanical testing. In the process of high frequency longitudinal resistance welding, the weld zone was heated quickly to a high austenization temperature which led to a coarse grain structure in this zone assisted by high pressure. The weld zone presented martenite and ferrite microstructure with irregular grain. As a result, the hardness of the weld zone reached 315 HV and the impact energy dropped to near zero. After annealing at 950 ℃ for 3 min, the decomposition of martensite was the main reason of the decrease of hardness (260 HV) in weld zone. The microstructure of weld zone was composed of ferrite and bainite, resulting in the increase of impact energy from 0 to 23 J.