LUCEFIN 50CrMo4 (1.7228)

Lucefin 50CrMo4 is a medium-carbon, chromium-molybdenum direct hardening alloy steel that is also suitable for flame hardening, induction hardening, and nitriding. This steel is a medium hardenability steel in the 0.45 to 0.50 mean carbon content classification. In general, it is used for medium and large size parts requiring high hardness as well as high strength and good toughness. A minimum of 90% martensite in the as-quenched condition is desirable. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming, heat treating, machining, and joining. Filing Code: SA-877. Producer or source: Lucefin S.p.A.

Optimization design and operating parameters of induction heat-ing system for hardening

The paper deals with the problem of optimizing the design and operating parameters of an induction heating system for surface hardening of a steel stepped shaft. The problem of optimal design of an inductor is formulated based on a nonlinear two-dimensional numerical model of coupled electromagnetic and temperature fields, developed in the ANSYS Mechanical APDL software. Alternance method of parametric optimization of systems with distributed parameters is used to optimize induction hardening system. MATLAB software has been used for developing parametric optimization subroutine, which was incorporated into the numerical ANSYS model to simulate a process of induction heating. Commonly used a multi-turn solenoid-style coil fabricated from rectangular copper tubing has been used as a hardening inductor. Besides that, an application of profiled copper turns has been investigated. Optimization of induction hardening system described above allows one to substantially improve heating uniformity and enhance metallurgical characteristics of as-hardened stepped shaft. Localized temperature surplus at an upper diameter shoulder has been minimized. At the same time, sufficient austenitization in the fillet area near stepped region (diameter transition) has been obtained.

Perfecting the Hardening Process with 3D Technology

Perfecting the induction process relies on fine-tuning every small detail. For the tool, this means the complex development process for the inductors using design software, high-precision production, and the correct positioning of the tool in the machine’s connection system. Applying different new and highly advanced 3D technologies such as FEM & CFD analysis and 3D printing of inductors will lead to a drastic increase of efficiency and the highest reproducibility for the entire process. When this happens, computer-aided accuracies of the inductors are compared with real manufactured inductors using 3D optical measurement methods and will reveal the advantages of this new process technology. The precision and process repeatability of this technology is showcased by various experimental test series’ that take the daily operational challenges for induction hardening as a benchmark.

Analysis of Errors in Simulation Modeling

Nowadays, the use of technologies to increase productivity, reduce time, as well as reduce the possibilities of errors, has become indispensable. All processes have opportunities for improvement, and this can be done based on calculations that with the support of computational systems can be reduced considerably in time. In the heat treatment industry and more specifically in the electromagnetic induction heat treatment industry is no exception. Today we have numerous tools to optimize the design process of inductors used in heat treatment of metals. These tools can show us, in a virtual way, the results that we can obtain before having to manufacture the inductors, all this based on FEA (Finite Elements Analysis) simulations that performing calculations considering physical parameters approximate us to what we would have as a result. Computer based simulation programs for induction heating and resulting metallurgy are extremely useful in developing tooling and process for induction heating. Induction hardening simulation brings elements of inductor design, steel properties such as time-temperature-transformation curves, both thermal and magnetic properties at various temperatures and cooling rates based on the phase of the quench media on cooling. A common method in place hardening (static hardening) knows as single shot hardening. In this process, the inductor is designed with a top and bottom half loop connected by heating rails. The length of heating is determined by the length of the rails and percentage height of the width of the half loops. Accurately predicting the length of the heating pattern in this 3D modeling approach is computationally a heavy load on the modeling pre-requisites. Commonly the inductor is modeled and then tested with the actual results showing a different length than what was predicted. It is important to consider that like any system, these simulation tools are not infallible and have several factors that can affect the accuracy of the simulation results. This paper reaches into the analysis of why the predicted length may differ prom the test results discussing what factors constitute the largest variance from the predicted outcome. Inductor design and the reliance on set up will be discussed.

Influence of Specimen Design on Maximum Heating Rate and Temperature Variation During Induction Heating in an 805L Dilatometer

Commercially, carbon steels are induction heated at heating rates on the order of 100 to 1,000 °C·s-1 for surface hardening. The high precision DIL 805L dilatometer employs induction heating and is often used to study transformation characteristics and prepare test specimens for metallurgical analysis. However, heating the commonly used 4 mm diameter by 10 mm long specimens at rates above 50 °C·s-1 results in non-linear heating rates during transformation to austenite and large transient temperature variations along the specimen length. These limitations in heating rate and variances from ideal uniform heating can lead to inaccurate characterization of the transformation behavior compared to commercial induction hardening practices. In this study it is shown that changing the specimen design to a thin wall tube allows faster heating rates up to 600 °C·s-1 and modifies the pattern of temperature variations within the test sample. The response of selected specimen geometries to induction heating in the dilatometer is characterized by modelling and tests using multiple thermocouples are used to verify the models. It is demonstrated that the use of properly designed tubular test specimens can aid in more accurately establishing transformation characteristics during commercial induction hardening.

3D Simulation of an Automotive Wheel Hub and Induction Hardening Coil to Solve Coil Lifetime Issues

This paper will revisit a case study originally done for ASM HTS Conference in 2009. The goal then was to solve an induction coil lifetime issue of an induction coil for heat treatment of an automotive wheel hub. At the time, computer simulation was beginning to allow for full virtual prototyping of heat treat applications as an alternative to experimental testing. While practical knowledge allowed for the successful determination of the cause of short coil life, and iterative simulation led to implementation of a longer lasting coil that met the required pattern, simulation was not used at the time to pinpoint the cause of failure. As faster computing becomes more widely available and finite element analysis (FEA) improves in scope and accuracy, virtual prototyping and detection of these failure modes are becoming faster and lower cost options compared to the traditional test and trial method. To highlight the leaps made in virtual prototyping, this case study that was previously done as an axisymmetric 2D model will be done in 3D electromagnetic plus thermal with rotation for the full part.

Does 3D-Printed Coil Perform Better for Induction Hardening and How to Predict the Performance Based on Numerical Simulation?

Recent developments in additive manufacturing (also called 3D printing of inductors) have opened new possibilities in the induction heating field by making inductors that have a longer service life and are more reproducible. Computer simulations were done to compare inductors made with two different techniques – conventional manufacturing and additive manufacturing. To compare inductor performance, heating of the soldered joints, the change in power consumption in the inductors and the temperature field in the workpiece were studied. Also, different steel structures such as austenite, bainite, pearlite, and martensite were studied to measure the case depth of the workpiece. All calculations were done by using CENOS simulation software, which uses a coupled electromagnetic-thermal model to describe the induction heating process. For the phase transition calculations a time temperature transformation diagram was used.

Program complex for optimization of surface hardening of steel billets

The aim of the paper is to develop program complex in software MATLAB with integrated numerical 2D nonlinear FLUX model, which is used for solving optimal inductor design and control problems for heating stage of surface induction hardening. Considered program complex is based on alternance method, that allows to write systems of transcendental equations, closed with respect to all unknown design and control parameters of the process. The suggestion for implementation of obtained optimal control algorithm is presented.