Integrated Hardfacing of Stellite-6 Using Hybrid Manufacturing Process

Hybrid manufacturing systems provide a platform for integrated additive, subtractive and inspection methods on a single machine setup. The present work explores use of hybrid manufacturing for hardfacing of performance components for improving wear resistance. In this work, Stellite-6 was applied to a 410 stainless steel substrate using a hybrid manufacturing system incorporating multi-axis directed energy deposition and machining. Experimental testing was conducted to determine the effects of hybrid manufacturing parameters on internal porosity, surface porosity and microstructure in the cladded material, as well as on the roughness of the final machined surface. Correlation between porosity measurements made by x-ray tomography and surface inspection is presented and determination of ideal process parameters for hardfacing of components using hybrid manufacturing systems is briefly discussed. A deposition process is presented and implemented on a large industrial component. The component is inspected using dye-penetrant testing and metallographic techniques.Mechanical Engineerin

Operando neutron diffraction reveals mechanisms for controlled strain evolution in 3D printing

Abstract Residual stresses affect the performance and reliability of most manufactured goods and are prevalent in casting, welding, and additive manufacturing (AM, 3D printing). Residual stresses are associated with plastic strain gradients accrued due to transient thermal stress. Complex thermal conditions in AM produce similarly complex residual stress patterns. However, measuring real-time effects of processing on stress evolution is not possible with conventional techniques. Here we use operando neutron diffraction to characterize transient phase transformations and lattice strain evolution during AM of a low-temperature transformation steel. Combining diffraction, infrared and simulation data reveals that elastic and plastic strain distributions are controlled by motion of the face-centered cubic and body-centered cubic phase boundary. Our results provide a new pathway to design residual stress states and property distributions within additively manufactured components. These findings will enable control of residual stress distributions for advantages such as improved fatigue life or resistance to stress-corrosion cracking

Efficacy of Habit Reversal Training in Children With Chronic Tic Disorders: A Within-Subject Analysis

The aim of this study is to evaluate a cognitive-behavioral treatment for children and adolescents with tic disorder including habit reversal training (HRT) in a sample of children and adolescents (n = 27). Multiple outcome measures were used to assess the effects of the treatment on tic symptoms. In addition, impairment/subjective burden ratings and the self-efficacy to control tics were assessed. A within-subject design with two phases (8 weeks diagnostic; 16 sessions treatment) was analyzed using multilevel modeling (MLM). During the treatment phase, significant improvements in tic symptoms, impairment, and self-efficacy to control tics were found on most outcome measures. Treatment effects were found on the clinical rating of tic symptoms (Yale Global Tic Severity Scale [YGTSS]), the self-efficacy to control tics, and the video-observed motor tic frequency by comparing the improvements during treatment with the course of the outcome measures during the preceding diagnostic phase