Effect of process parameters on interfacial temperature and shear strength of ultrasonic additive manufacturing of carbon steel 4130

Author(s):  
Tianyang Han ◽  
Leon M Headings ◽  
Ryan Hahnlen ◽  
Marcelo J. Dapino

Abstract Ultrasonic additive manufacturing (UAM) is a solid state manufacturing process capable of producing near-net-shape metal parts. Recent studies have shown the promise of UAM welding of high strength steels. However, the effect of weld parameters on the weld quality of UAM steel is unclear. A design of experiments study based on a Taguchi L16 design array was conducted to investigate the influence of parameters including baseplate temperature, amplitude, welding speed, and normal force on the interfacial temperature and shear strength of UAM welding of carbon steel 4130. Analysis of variance (ANOVA) and main effects analyses were performed to determine optimal weld parameters within the process window. A Pearson correlation test was conducted to find the relationship between interfacial temperature and shear strength. These analyses indicate that the highest shear strength of 392.8 MPa can be achieved by using a baseplate temperature of 400°F (204.4°C), amplitude of 31.5 μm, welding speed of 40 in/min (16.93 mm/s), and normal force of 6000 N. The Pearson correlation coefficient is calculated as 0.227, which indicates a weak positive correlation between interfacial temperature and shear strength over the range tested.

Author(s):  
Ryan Hahnlen ◽  
Marcelo J. Dapino

Shape memory and superelastic NiTi are often utilized for their large strain recovery and actuation properties. The objective of this research is to utilize the stresses generated by pre-strained NiTi as it is heated in order to tailor the CTE of metal-matrix composites. The composites studied consist of an Al 3003-H18 matrix with embedded NiTi ribbons fabricated through an emerging rapid prototyping process called Ultrasonic Additive Manufacturing (UAM). The thermally-induced strain of the composites is characterized and results show that the two key parameters in adjusting the effective CTE are the NiTi volume fraction and prestrain of the embedded NiTi. From the observed behavior, a constitutive composite model is developed based constitutive SMA models and strain matching composite models. Additional composites were fabricated to characterize the NiTi-Al interface through EDS and DSC. These methods were used to investigate the possibility of metallurgical bonding between the ribbon and matrix and determine interface shear strength. Interface investigation indicates that mechanical coupling is accomplished primarily through friction and the shear strength of the interface is 7.28 MPa. Finally, using the developed model, a composite was designed and fabricated to achieve a near zero CTE. The model suggests that the finished composite will have a zero CTE at a temperature of 135°C.


Author(s):  
C. D. Hopkins ◽  
M. J. Dapino ◽  
S. A. Fernandez

Ultrasonic additive manufacturing (UAM) is an emerging solid-state fabrication process that can be used for layered creation of solid metal structures. In UAM, ultrasonic energy is used to induce plastic deformation and nascent surface formation at the interface between layers of metal foil, thus creating bonding between the layers. UAM is an inherently stochastic process with a number of unknown facets that can affect the bond quality. In order to take advantage of the unique benefits of UAM, it is necessary to understand the relationship between manufacturing parameters (machine settings) and bond quality by quantifying the mechanical strength of UAM builds. This research identifies the optimum combination of processing parameters, including normal force, oscillation amplitude, weld speed, and number of bilayers for the manufacture of commercially pure, grade 1 titanium+1100-O aluminum composites. A multifactorial experiment was designed to study the effect of the above factors on the outcome measures ultimate shear strength and ultimate transverse tensile strength. Generalized linear models were used to study the statistical significance of each factor. For a given factor, the operating levels were selected to cover the full range of machine capabilities. Transverse shear and transverse tensile experiments were conducted to quantify the bond strength of the builds. Optimum levels of each parameter were established based on statistical contrast trend analyses. The results from these analyses indicate that high mechanical strength can be achieved with a process window bounded by a 1500 N normal force, 30 μm oscillation amplitude, about 42 mm/s weld speed, and two bilayers. The effects of each process parameter on bond strength are discussed and explained.


Author(s):  
Paul J. Wolcott ◽  
Christopher Pawlowski ◽  
Leon M. Headings ◽  
Marcelo J. Dapino

Ultrasonic welding was investigated as a method of joining 0.076 in. (1.93 mm) thick aluminum 6061 flat sheet material. Joints were produced with ultrasonic additive manufacturing (UAM) equipment in a modified application of the ultrasonic welding process. Through joint design development, successful welds were achieved with a scarf joint configuration. Using a design of experiments (DOE) approach, weld parameters including weld amplitude, scarf angle, and weld speed were optimized for mechanical strength. Lower angles and higher amplitudes were found to provide the highest strengths within the levels tested. Finite-element studies indicate that 5 deg and 10 deg angles produce an increased relative motion of the workpieces as compared to 15 deg, 20 deg, and 25 deg angles, likely leading to increased strength. Successful joints showed no indication of voids under optical microscopy. As-welded joints produce tensile strengths of 221 MPa, while heat treated joints produce tensile strengths of 310 MPa, comparable to heat treated bulk material. High-temperature tensile testing was conducted at 210 °C, with samples exhibiting strengths of 184.1 MPa, similar to bulk material. Room temperature fatigue testing resulted in cyclic failures at approximately 190,000 cycles on average, approaching that of bulk material.


2011 ◽  
Vol 17 (5) ◽  
pp. 369-379 ◽  
Author(s):  
David Schick ◽  
Sudarsanam Suresh Babu ◽  
Daniel R. Foster ◽  
Marcelo Dapino ◽  
Matt Short ◽  
...  

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