In this research project,copper and stainless steel were connected by two laser welding methods:straight seam welding and swing welding.Then,electronic tensile test machine,X-ray diffractometer,scanning electron micro...In this research project,copper and stainless steel were connected by two laser welding methods:straight seam welding and swing welding.Then,electronic tensile test machine,X-ray diffractometer,scanning electron microscope and metallographic microscope were used to analyze the tensile properties,macroscopic and microscopic structure morphology and phase of the welded joint.Based on the experimental results,we determined that the strength of the straight seam welded joint was higher.Because of the intermetallic compound near the weld in the swing welding process,it leads to stress concentration,crack cracking and strength reduction.In addition,the oscillating laser beam also leads to the disorderly direction of columnar crystal and coarse structure,which makes the joint strength decrease.展开更多
In this study, we present the experimental laser welding of super-eutectic Zn-Al(ZA) alloy. Microstructure characteristics of the ZA alloy’s bond area welded by pulsed laser were investigated using an optical microsc...In this study, we present the experimental laser welding of super-eutectic Zn-Al(ZA) alloy. Microstructure characteristics of the ZA alloy’s bond area welded by pulsed laser were investigated using an optical microscope, scanning electron microscope, energy diffraction spectrum and X-Ray diffraction. The results showed that the microstructures in the weld mainly consisted of threadlike columnar crystals, coarse dendrites and fine equiaxed grains. Secondary particles were produced in the interdendritic zones due to the composition segregation. A poor Al area was formed in η grain inside while a rich Al area took shape outside the η grain. The occurrence of the composition segregation increased the grain boundary cracking tendency. The existence of a large number of η phases greatly increased the brittle of this material. The presence of many cleavage steps in the fractograph principally depended on the secondary cleavage effect between two cleavage cracks in different planes. The evolution of cracks along the twinning plane was the result of the secondary cleavage substituting for the twinning deformation in the vicinity of the crack tip.展开更多
基金Supported by the National Natural Science Foundation of China(51801057,51702091,12104140)the Natural Science Foundation of Hubei Province(2020CFB245)+2 种基金the Hubei Province Education Department Scientific Research Plan Guiding Project(B2017215,B2021260)the Research Start-up Funding of Hubei University of Education(19RC03,20RC09)the 2021 Science and Technology Development Plan of Henan Province(212102210336)。
文摘In this research project,copper and stainless steel were connected by two laser welding methods:straight seam welding and swing welding.Then,electronic tensile test machine,X-ray diffractometer,scanning electron microscope and metallographic microscope were used to analyze the tensile properties,macroscopic and microscopic structure morphology and phase of the welded joint.Based on the experimental results,we determined that the strength of the straight seam welded joint was higher.Because of the intermetallic compound near the weld in the swing welding process,it leads to stress concentration,crack cracking and strength reduction.In addition,the oscillating laser beam also leads to the disorderly direction of columnar crystal and coarse structure,which makes the joint strength decrease.
基金Supported by the National Natural Science Foundation of China(51801057)the Natural Science Foundation of Hubei Province(2018CFB296)+1 种基金the Major Project of Technological Innovation(2016AAA038)College Outstanding Young Scientific and Technological Innovation Team of Hubei Province(T201620).
文摘In this study, we present the experimental laser welding of super-eutectic Zn-Al(ZA) alloy. Microstructure characteristics of the ZA alloy’s bond area welded by pulsed laser were investigated using an optical microscope, scanning electron microscope, energy diffraction spectrum and X-Ray diffraction. The results showed that the microstructures in the weld mainly consisted of threadlike columnar crystals, coarse dendrites and fine equiaxed grains. Secondary particles were produced in the interdendritic zones due to the composition segregation. A poor Al area was formed in η grain inside while a rich Al area took shape outside the η grain. The occurrence of the composition segregation increased the grain boundary cracking tendency. The existence of a large number of η phases greatly increased the brittle of this material. The presence of many cleavage steps in the fractograph principally depended on the secondary cleavage effect between two cleavage cracks in different planes. The evolution of cracks along the twinning plane was the result of the secondary cleavage substituting for the twinning deformation in the vicinity of the crack tip.
