论文部分内容阅读
随着能源业的发展,Fe-36%Ni合金作为结构材料的应用需求越来越广,而电弧焊时存在严重的热裂纹和再热裂纹问题。采用搅拌摩擦焊方法焊接Fe-36%Ni合金可以有效地避免电弧焊带来的裂纹问题,获得成形良好的接头。但已有研究获得的焊缝组织均有晶粒粗化的特点,导致其接头力学性能低于母材。因此,需要解决晶粒粗化问题,寻找组织与性能获得改善的方法。采用控制焊接工艺的方法改善Fe-36%Ni合金搅拌摩擦焊接头的组织和性能。结果表明,在较低的焊接速度下,调整搅拌头转速更适合于控制Fe-36%Ni合金搅拌摩擦焊接头的晶粒尺寸。搅拌头低转速带来较低的焊接热输入,使焊缝具有晶粒尺寸与母材相当或较母材晶粒细化的组织。晶粒尺寸是接头力学性能的主导因素。在400 r/min和2 mm/s的焊接工艺下可获得与母材晶粒尺寸相近、强度和硬度相当、断后伸长率也较高的接头。
With the development of the energy industry, the application requirements of Fe-36% Ni alloy as structural material are more and more widely, and there are serious problems of hot crack and reheat crack in arc welding. Friction stir welding method of welding Fe-36% Ni alloy can effectively avoid the arc welding caused by the problem of cracking, to obtain a well-formed joints. However, the weld microstructures obtained from previous studies all have the characteristics of coarsening of the grains, resulting in the mechanical properties of the joint being lower than that of the base metal. Therefore, there is a need to solve the problem of grain coarsening and find ways to improve the organization and performance. The microstructure and properties of Fe-36% Ni alloy friction stir welded joints were improved by controlled welding process. The results show that, at lower welding speed, adjusting the speed of stirring head is more suitable for controlling the grain size of friction stir welded joints of Fe-36% Ni alloy. The low speed of the mixing head leads to a lower welding heat input, giving the weld microstructure with a grain size that is comparable to the base metal or grain refinement of the base metal. The grain size is the dominant factor in the mechanical properties of the joint. Under the welding conditions of 400 r / min and 2 mm / s, the joints with similar strength and hardness to the base metal and higher elongation after fracture can be obtained.