Simulation of multi-frequency-induction-hardening including phase transitions and mechanical effects

Induction hardening is a well known method for the heat treatment of steel components. With the concept of multi-frequency hardening, where currents with two different frequency components are provided on a single inductor coil, it is possible to optimize the hardening zone to follow a given contour, e.g. of a gear. In this article, we consider the simulation of multi-frequency induction hardening in 3D. The equations to solve are the vector potential formulation of Maxwell's equations describing the electromagnetic fields, the balance of momentum to determine internal stresses and deformations arising from thermoelasticity and transformation induced plasticity, a rate law to determine the distribution of different phases and the heat equation to determine the temperature distribution in the workpiece. The equations are solved using adaptive finite element methods. The simulation results are compared to experiments for discs and for gears. A very good agreement for the hardening profile and the temperature is observed. It is also possible to predict the distribution of residual stresses after the heat treatment

In Situ X-Ray Diffraction Analysis of Microstructure Evolution during Deep Cryogenic Treatment and Tempering of Tool Steels

Deep cryogenic treatment of tool steels, incorporated in conventional hardening and tempering, has been a topic of intensive research in recent years. Yet, the governing microstructural mechanisms involved in the deep cryogenic treatment of high-alloyed tool steels are still controversial. Thus, an in situ X-ray diffraction study is conducted on three tool steels X38CrMoV5-3, X153CrMoV12, and ~X190CrVMo20-4 to shed light on microstructural evolution during cryogenic treatment and subsequent tempering. For these high-alloyed tool steels, the transformation of retained austenite into martensite is detected during the cooling phase of the cryogenic treatment. A change in tetragonality of martensite occurs mainly in the heating phase of the subsequent tempering process, which indicates the diffusion of carbon and carbide precipitation from the martensite. The microstructure evolution of the tool steels after hardening, cryogenic treatment, and tempering is further examined by scanning electron microscopy. © 2021 The Authors. Steel Research International published by Wiley-VCH Gmb

Methodological strategies to understand smartphone practices for social connectedness in later life

Digital practices in later life are not yet well understood. Therefore, this paper discusses the framework for a research design project that aims at tracing differences and similarities in how older adults use their smartphones in circumstances in and outside their homes in Spain, the Netherlands, Sweden, and Canada. The research questions of this international research project focus on the extent to which digital mobile practices relate to perceived social connectedness among older adults aged 55–79 years old. While studies have shown that the subjective experience of ‘being connected’ supports continued wellbeing in later life, there remains an insufficient understanding of the processes through which digital mediated social interaction is effective for social connectedness. The analytical framework of the project prioritizes the co-constituency of (digital) technology and ageing, and takes digital practices in everyday life as its entry point. The main data collection tool will be the tracking of smartphone activity of 600 older adults (150 per country) during four weeks. An online survey and qualitative interviews will gather data about the meanings of the quantified digital practices, and how they shape (if they do) the participants’ connection to the world. This approach will allow us not only to get insight into what older adults say how they used their smartphone but also to gain insight into their real-life daily use. The assessment of the challenges, strengths, and weaknesses of the methods contributes towards an accurate and appropriate interpretation of empirical results and their implications

Development of micro rotary swaging tools of graded tool steel via co-spray forming

In order to meet the requirements of micro rotary swaging, the local properties of the tools should be adjusted properly with respect to abrasive and adhesive wear, compressive strength, and toughness. These properties can be optimally combined by using different materials in specific regions of the tools, with a gradual transition in between to reduce critical stresses at the interface during heat treatment and in the rotary swaging process. In this study, a newly developed co-spray forming process was used to produce graded tool materials in the form of a flat product. The graded deposits were subsequently hot rolled and heat treated to achieve an optimal microstructure and advanced properties. Micro plunge rotary swaging tools with fine geometrical structures were machined from the hot rolled materials. The new forming tools were successfully applied in the micro plunge rotary swaging of wires of stainless steel

Development of micro rotary swaging tools of graded tool steel via co-spray forming

In order to meet the requirements of micro rotary swaging, the local properties of the tools should be adjusted properly with respect to abrasive and adhesive wear, compressive strength, and toughness. These properties can be optimally combined by using different materials in specific regions of the tools, with a gradual transition in between to reduce critical stresses at the interface during heat treatment and in the rotary swaging process. In this study, a newly developed co-spray forming process was used to produce graded tool materials in the form of a flat product. The graded deposits were subsequently hot rolled and heat treated to achieve an optimal microstructure and advanced properties. Micro plunge rotary swaging tools with fine geometrical structures were machined from the hot rolled materials. The new forming tools were successfully applied in the micro plunge rotary swaging of wires of stainless steel

Development of micro rotary swaging tools of graded tool steel via co-spray forming

In order to meet the requirements of micro rotary swaging, the local properties of the tools should be adjusted properly with respect to abrasive and adhesive wear, compressive strength, and toughness. These properties can be optimally combined by using different materials in specific regions of the tools, with a gradual transition in between to reduce critical stresses at the interface during heat treatment and in the rotary swaging process. In this study, a newly developed co-spray forming process was used to produce graded tool material in the form of a flat product. The graded deposit was subsequently hot rolled and heat treated to achieve an optimal microstructure and advanced properties. Micro plunge rotary swaging tools with fine geometrical structures were machined from the hot rolled material. The new forming tools were successfully applied in the micro plunge rotary swaging of wires of stainless steel

Development of micro rotary swaging tools of graded tool steel via co-spray forming

In order to meet the requirements of micro rotary swaging, the local properties of the tools should be adjusted properly with respect to abrasive and adhesive wear, compressive strength, and toughness. These properties can be optimally combined by using different materials in specific regions of the tools, with a gradual transition in between to reduce critical stresses at the interface during heat treatment and in the rotary swaging process. In this study, a newly developed co-spray forming process was used to produce graded tool materials in the form of a flat product. The graded deposits were subsequently hot rolled and heat treated to achieve an optimal microstructure and advanced properties. Micro plunge rotary swaging tools with fine geometrical structures were machined from the hot rolled materials. The new forming tools were successfully applied in the micro plunge rotary swaging of wires of stainless steel

Simulation of multi-frequency-induction-hardening including phase transitions and mechanical effects

Induction hardening is a well known method for the heat treatment of steel components. With the concept of multi-frequency hardening, where currents with two different frequency components are provided on a single inductor coil, it is possible to optimize the hardening zone to follow a given contour even in the case of complicated 3D geometries like gears. In this paper, we consider the simulation of multi-frequency induction hardening in 3D. The equations to solve are the magneto-quasistatic approximation of Maxwell׳s equations describing the electromagnetic fields, the balance of momentum to determine internal stresses and deformations arising from thermoelasticity and transformation induced plasticity (TRIP), a rate law to determine the distribution of different phases and the heat equation to determine the temperature distribution in the workpiece. The equations are solved using adaptive finite element methods. The simulation results are compared to experiments for discs and for gears. A very good agreement for the hardening profile and the temperature is observed. It is also possible to predict the distribution of residual stresses after the heat treatment