Marques Eva S V, Silva F J G, Paiva Olga C, Pereira António B
ISEP-School of Engineering, Polytechnic of Porto, 4249-015 Porto, Portugal.
TEMA-Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
Materials (Basel). 2019 Jul 14;12(14):2263. doi: 10.3390/ma12142263.
The main advantage of welding cast iron is to recover parts by repairing defects induced by casting processes (porosities, etc.), before they enter their working cycle, as well as repair cracks or fractures when already in service. This method contributes to decreased foundry industrial waste and avoids the additional energy costs of their immediate recycling. Therefore, it is necessary to have a welded joint with similar or better characteristics than the parent material. The major problem of welding cast iron is that this material has a very high content of carbon in comparison to steel (≈3%). Therefore, when it is heated by the very high temperatures from arc welding and during its process of solidification, very hard and brittle phases originate, known as ledeburite and martensite, and appear in the partially melted zone and in the heat-affected zone. Eventually, this problem can be solved by implementing heat treatments such as preheat or post weld heat treatments under specific parameters. Therefore, in this study, the aim is to collect data about the effects of heat treatments performed at different temperatures on welded joints of high strength ductile cast iron (SiboDur 450), and to evaluate the effects of heat treatments performed at diverse temperatures on welded joints of this type of material, using Shield Metal Arc Welding and nickel electrodes. Mechanical strength, hardness, and microstructure were analyzed, showing that the best mechanical strength in the joint (380 MPa) was obtained using two passes of E C Ni-Cl (ISO EN 1071:2015) filler metal and post weld heat treatments (PWHT) of 400 °C for two hours.
焊接铸铁的主要优点是在零件进入工作周期之前修复铸造过程中产生的缺陷（如气孔等），从而回收零件，以及在零件投入使用后修复裂纹或断裂。这种方法有助于减少铸造工业废料，并避免其直接回收所需的额外能源成本。因此，需要有一个与母材具有相似或更好性能的焊接接头。焊接铸铁的主要问题是，与钢相比，这种材料的碳含量非常高（约3%）。因此，当它被弧焊的高温加热以及在凝固过程中，会产生非常硬且脆的相，即莱氏体和马氏体，并出现在部分熔化区和热影响区。最终，这个问题可以通过实施特定参数下的预热或焊后热处理等热处理来解决。因此，在本研究中，目的是收集关于不同温度下的热处理对高强度球墨铸铁（SiboDur 450）焊接接头影响的数据，并使用手工电弧焊和镍电极评估不同温度下的热处理对这种材料焊接接头的影响。对机械强度、硬度和微观结构进行了分析，结果表明，使用两道次的E C Ni-Cl（ISO EN 1071:2015）填充金属和400℃两小时的焊后热处理（PWHT）可获得接头最佳机械强度（380MPa）。
