纳米贝氏体钢再纳米化焊接接头组织和性能

采用TIG焊方法对纳米贝氏体钢板进行表面堆焊并快速进行再纳米化处理,通过SEM和TEM观察了焊接接头不同区域的组织特征和形态,使用XRD和TEM电子衍射花样对各种相进行鉴定,并获得相应相的含量,采用拉伸试验和硬度测试获得了再纳米化焊接接头的力学性能.结果表明,经过再纳米化处理,纳米贝氏体钢焊缝区和淬火区组织转变为纳米级片层状的贝氏体和奥氏体,其中焊缝奥氏体含量为13%,而且淬火区片层厚度与母材相当约为70 nm,焊缝区片层厚度大于母材约为300 nm.力学性能测试结果表明,再纳米化焊接接头抗拉强度为1500 MPa,硬度为7000 MPa,与母材相差无几,其中接头断裂位置为回火区,是由于回火区析出大量碳化物导致的.

Microstructure and mechanical properties of welded joint of nanostructured bainite steel with regeneration

Due to the poor weldability of nanostructured bainite steel,a method called welding with regeneration was proposed to obtain a welded joint with the same microstructure as the base metal,so the welded joint could possess the excellent mechanical properties. Regeneration treatment was used after tungsten inert gas (TIG) welding of nanostructured bainite steel. The microstructures of the welded joint were characterized by X-ray diffraction,scanning electron and transmission electron microscopes. The tensile and microhardness tests were carried out to evaluate the mechanical properties. The results show that nanostructured bainite was obtained in the fusion zone and quenched zone with 300 nm and 70 nm thick bainite plates,respectively. The tensile strength of the welded joint was 1 500 MPa,and the microhardness in the fusion zone was 7 000 MPa,which were almost equivalent to those of the base metal.