EH36钢埋弧焊接头焊缝金属不均匀性对断裂行为的影响

Research on the effects of EH36 weld metal inhomogeneity on fracture behavior

关键词:  EH36钢  焊缝金属  裂纹起裂

Key words:  EH36 steel  weld metal  crack initiation

摘要:

为研究EH36钢埋弧焊焊缝金属组织不均匀性对裂纹起裂行为的影响，采用微小力学试验系统，对EH36钢埋弧焊焊缝中两种不同取向试样进行微拉伸试验，并对两组试样裂纹萌生机理进行显微观察. 结果表明,两组试样塑性变形均集中在先共析铁素体上，且先共析铁素体上应变分布不均匀；横向加载试样为微孔聚集型断裂，由于“弱”应力奇异性的存在，裂纹在应变集中作用下起源于三叉晶界；纵向加载试样变形集中在先共析铁素体与针状铁素体界面处并导致界面剥离生成裂纹，断口具有局部脆性的特征.

Abstract:

The specimens were cut from weld metal in two orientations, and the micro-tensile test was conducted. The appearance of tensile specimens at different strains were observed with metallographic microscope, confocal laser scanning microscope and scanning electron microscope (SEM) to study the surface morphology and local deformation of specimens during tensile tests. What's more, the fracture morphology of specimens was observed with SEM. The results indicate that plastic deformation concentrates in proeutectoid ferrite in both kinds of specimens and the plastic deformation in PF is not homogenous; for vertical specimen, under the effect of strain concentration which is related to weak stress singularities, the crack starts in grain triple junctions; crack initiation districts of horizontal specimen have the characteristic of local brittle, the crack initiates by interfacial decohesion at proeutectoid ferrite /acicular ferrite interfaces, as a result of plastic deformation concentration in the interface of acicular ferrite and proeutectoid ferrite.