Coupled Thermomechanical Response Measurement of Deformation of Nickel-Based Superalloys Using Full-Field Digital Image Correlation and Infrared Thermography

The paper is devoted to highlighting the potential application of the quantitative imaging technique through results associated with work hardening, strain rate and heat generated during elastic and plastic deformation. The aim of the research presented in this article is to determine the relationship between deformation in the uniaxial tensile test of samples made of 1-mm-thick nickel-based superalloys and their change in temperature during deformation. The relationship between yield stress and the Taylor–Quinney coefficient and their change with the strain rate were determined. The research material was 1-mm-thick sheets of three grades of Inconel alloys: 625 HX and 718. The Aramis (GOM GmbH, a company of the ZEISS Group) measurement system and high-sensitivity infrared thermal imaging camera were used for the tests. The uniaxial tensile tests were carried out at three different strain rates. A clear tendency to increase the sample temperature with an increase in the strain rate was observed. This conclusion applies to all materials and directions of sample cutting investigated with respect to the sheet-rolling direction. An almost linear correlation was found between the percent strain and the value of the maximum surface temperature of the specimens. The method used is helpful in assessing the extent of homogeneity of the strain and the material effort during its deformation based on the measurement of the surface temperature.

Hydrophobic sealing materials for harsh environmental electrical connector package applications

A highly hydrophobic sealing material system has been developed using high-temperature melt-quenching and sintering technologies for harsh environmental electrical connector package sealing applications. The sealing material properties can be varied by its phase structures, such as amorphous glass, crystalline monoclinic and tetragonal mixed phase, and covalent bond tetragonal phase, which are determined by a two-stage synthesizing process. The dilatometer measurements have found that the ambient coefficient of thermal expansion varies from ~5.8 to 7.1 ppm/°C while the coefficient of thermal expansion at its glass transition temperatures varies from ~7.0 to 9.0 ppm/°C. These coefficients of thermal expansion could provide not only wide options for integrating metal materials, such as Ti-alloy, Kovar, Inconel alloys, and Stainless Steels for making reliable electrical connector packages, but also enable the design of electrical connector packages with a safety factor of 3 performance, operable at 30KSI (30,000 PSI) pressure, and −100 −300°C harsh conditions while maintaining at least 5,000MΩ insulation resistances, for reliable signal, data, and electrical power transmissions.

Machining Performance Optimization for Turning of Inconel 825: An integrated Optimization Route Combining Grey Relation Analysis with JAYA and TLBO

With the widespread application of Inconel alloys in manufacturing industries especially in the automobile as well as aerospace industries leads to manufacturers to pay more attention towards the understanding of machinability aspects of these alloys. Attributable to the need for large-scale manufacturing of Inconel machined components, the optimization of machining process variables become crucial to produce quality products economically by means of enhancing process performance. In common, several process parameters namely depth of cut, feed rate, and spindle speed influence the performance of turning operation in their own way. Concurrently, in the machining of Inconel alloys, the important performance indices are Material Removal Rate (MRR), surface roughness, and cutting force. This work deals with the assessment of process performance of Inconel 825 alloy amid turning operation. For the optimization of multiple responses, grey relation analysis has been employed that transforms the multiple responses into a corresponding single response known as overall grey relation index (OGI). Based on OGI, as a function of selected process variables, formulation of a non-linear regression model has been done and considered as the fitness function. To conclude, two evolutionary techniques, Teaching-Learning-Based Optimization, well famous as TLBO, and JAYA algorithm have been considered for optimization.

An Improved Omega-Based Method for Creep Life Prediction Using Hyperbolic Sine Stress Correlation

This paper is concerned with the creep life prediction of cast 20Cr32NiNb alloy, an alternative candidate material to wrought Inconel alloys for use in the gas collector pipes of CO reformers which suffer from long-term creep damage due to high temperatures and stresses. Uniaxial creep tests of 20Cr32NiNb alloy were performed at 890 °C and 950 °C for different stresses. The Omega method for creep life prediction is applied to the 20Cr32NiNb tests and shown to give reasonably accurate prediction, particularly at low stress levels. A new method, based on the use of a hyperbolic sine function for stress correlation at specific temperatures for identification of the characteristic Omega parameters is presented and validated.