Experimental and Simulative Studies on Residual Stress Formation for Laser-Beam Surface Hardening*

Abstract

The results of high spatially resolved X-ray diffraction (XRD) analyses of residual stresses in laser-line hardened 42CrMo4 tempering steel samples are comparedwith the results of numerical process simulations and carefully discussed. Samples were locally line hardened at different maximum temperatures (950 °C, 1150 °C) and with different laser-beam feeds (200 mm/min, 800 mm/min) for the investigations. In addition to X-ray diffraction analyses, the effect of the process parameters on the formation of local microstructures was also examined. The results show that experimentally determined compressive residual stresses in process zones transverse and parallel to the laser track increase as temperatures decrease and feed increases. The dimensions of hardened zones (width, depth) affected by laser hardening at lower maximum temperatures are clearly smaller than those affected by laser hardening at higher temperatures, whilst the impact of laser-beam feed is less pronounced. A new model was developed for numerical simulation of laser-line hardening processes, showing good agreement between numerically calculated and experimentally determined microstructures in the process zones. The results of residual stresses calculated by simulation also exhibit good qualitative and largely also quantitative agreement with experimentally determined residual stresses. Partly, the simulation predicts some local deviations in the distribution of residual stresses.

50 Hz X‐Ray Diffraction Stress Analysis and Numerical Process Simulation at Laser Surface Line Hardening of Web Structures

“…Figure 4c) a semimodel was generated. A general description of the laser hardening simulation approach with the utilized ABAQUS subroutines is given in the study by Kiefer et al [ 25 ] The temperature dependencies of thermal and mechanical properties of the occurring phases are given by a third‐order polynomial approach, where the resulting quantities were homogenized according to their phase volume fraction. A precise specification of the input parameters is given in the study by Kaiser et al [ 26 ] First, a purely thermal simulation is carried out for every specimen model, thereby a nodal temperature field is computed.…”

Improving the Inner Surface State of Thick-Walled Tubes by Heat Treatments with Internal Quenching Considering a Simulation Based Optimization

“…In contrary, parts are treated separately during induction and laser hardening. One main advantage of these processes is the localized heating provided by induction or the high intensity laser beam resulting in efficient short austenitization times [7,8]. So far, none of the mentioned heat treatment methods is applicable to hard accessible inner surfaces.…”

Determination of Temperature-Dependent Elastic Constants of Steel AISI 4140 by Use of In Situ X-ray Dilatometry Experiments

“…In this regard the DECs determined using the herein proposed dilatometry approach will be used to improve current experimental data on laser surface hardening. Furthermore, averaged macroscopic elastic parameters can directly be used to improve finite element (FE) heat treatment process simulations [14].…”