S355钢T形接头高周疲劳性能

在工程领域中焊接构件极易产生疲劳断裂，引起各行业广泛关注。文中以T形接头为研究对象，采用MIG焊对S355钢板进行T形接头焊接试验，并对焊接接头进行金相组织和硬度分析。结果表明，焊缝主要为先共析铁素体、珠光体、粒状贝氏体和少量针状铁素体；熔合区成分和组织不均匀，晶粒大小不一致；过热区晶粒较粗大且不均匀；正火区组织主要为铁素体和珠光体，晶粒细小均匀。焊接接头的硬度高于母材，最高硬度出现在热影响区。对T形接头焊接试样进行轴向高周疲劳试验，通过最小二乘法拟合试验数据，得到疲劳S-N曲线。

High-cycle fatigue performance of S355 steel T-joint

In the field of engineering, fatigue fracture of welded components is very easy to occur, which has attracted extensive attention in various industries.In order to analyze the microstructure and fatigue properties of typical welded components, T-joint were studied in this paper.Welding tests of T-joint of S355 steel were completed by MIG welding, and microstructure and hardness of welded joints were analyzed.The weld mainly contained pro-eutectoid, ferrite pearlite, granular bainite and a small amount of acicular ferrite.Composition and microstructure of fusion zone were not uniform, grain size was not consistent, and grains of overheated zone were coarser and uneven.Microstructure of normalized zone was mainly ferrite and pearlite, and grains were fine and uniform.Hardness of welded joints was higher than that of base metal, and hardness of heat-affected zone was the highest.Axial high-cycle fatigue tests on welded specimens of T-Joints were conducted, test data was processed and fitted by the least square method, and S-N curve was obtained.