Microstructure and Wear Behavior of Cermet/Iron Alloy Cladding Layers on A6061 Alloy Coated by Resistance Seam Welding Method

Cermet/iron alloy cladding layers were coated on the surface of Al-Mg-Si alloy （A6061） plates by resistance seam welding method with tungsten carbide （WC） and high-carbon iron alloy （SHA） powders. The cladding layer consisted of WC reinforcement, SHA binder, A6061 and FeAl3. The effect of WC ratio （30 wt%, 50 wt% and 70 wt%） on the microstructure and wear behavior of the cladding layers was investigated in detail. Abrasive wear test was performed under two kinds of load condition by using a rubber wheel apparatus to evaluate wear resistance. The results showed that the wear resistance of the cladding layer was improved by 3.5-5 times than that of the substrate. At lower load, the wear resistances of the samples 30% and 70% WC were nearly the same, which suggested that FeAl3 played an important role in improvement of the wear resistance instead of WC. While at higher load, the amount of WC determined the wear resistance of the cladding layer. Furthermore, wear behavior of these cladding layers was explained with reference to the observed microstructure of the worn surface.

Lap joining of titanium alloy using laser welding and resistance seam welding combined process

Titanium alloy lap joints were performed by combined laser welding and resistance seam welding process. The welding characteristics of this combined process were investigated compared with that of laser welding. The experimental results indicate that the combined process welded joint has larger weld width at the lap surface. The joint tensile shear force of combined process is 2. 5 times that of laser welding. There are some pores around the lap surface in laser welded joint, and most pores can be eliminated by resistance seam welding process. Metallographic examinations of combined process welded joint reveal that the microstructure in heat-affected zone （HAZ） and weld zone has the acicular martensite morphology, which causes that the microhardness in HAZ and weld zone increases compared with the base metal, and the microhardness in weld zone is highest.

Microstructure and Properties of SiCp/Al Composite Materials Fabricated via Powder Packed Resistance Additive Manufacturing

SiC particle(SiCp)/Al composite materials were fabricated via powder packed resistance seam welding additive manufacturing.The influence of welding speed on microstructure and mechanical properties of the specimen was investigated,elucidating the formation and fracture mechanism of single-pass multi-layer deposition.The results demonstrate that a dense internal structure of the specimen characterized by uniformly dispersed SiCp embedded within the Al matrix is formed.However,particle agglomeration and porosity defects are observed.The porosity increases with the increase in welding speed,and the microstructure of the RSAM-24 specimen has the highest density,characterized by a density of 2.706 g/cm^(3)and a porosity of 1.672%.The mechanical properties of the specimens decrease as the welding speed increases.Optimal mechanical properties are obtained when the welding speed is set as 24 cm/min.Specifically,the average hardness,tensile strength and elongation values are 463.736 MPa,52.16 MPa and 2.2%,respectively.The tensile specimens predominantly exhibit fracture along the interlayer bonding interface and the interface between the Al matrix and SiC particles,and the damage mode is ductile fracture.