Transformation Plasticity in Carbonitrided PM-Steels: Quantification of Plasticity Effects in Dependence of the Part Density*

2021 ◽  
Vol 76 (6) ◽  
pp. 458-477
Author(s):  
J. M. Damon ◽  
S. Dietrich ◽  
V. Schulze
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
Volume Change ◽  
Surface Zone ◽  
Transformation Plasticity ◽  
Plasticity Mechanism ◽  
Treatment Processes ◽  
Precise Knowledge ◽  
Significant Difference ◽  
Part Density

Abstract To optimize heat treatment processes of case hardened components, heat treatment simulations are used to predict surface layer conditions. Only a precise knowledge and modelling of the transformation processes allows a trustworthy prediction of the hardness and residual stresses in the surface zone. The transformation plasticity mechanism plays an essential role in the heat treatment process and its correct simulation has a significant influence on the resulting calculated residual stress profiles and component distortion. Without considering transformation plasticity, simulative residual stresses are significantly overestimated [1]. In this work, powder metallurgical components are pressed and sintered and subsequently carbonitrided for a dilatometric investigation to characterize the correlation between transformation plasticity effect and the density. The results show a dependence of the austenite-martensite volume change that led to a significant difference of 0.5 Vol-%. A model describing the martensite volume change with respect to density is proposed. This also affects the description of the transformation plasticity constants (K) between K = 5 – 6 × 10–5 MPa–1 in dependence of density. With currently available data, the effect of chemical composition and density cannot be separated and quantified and further studies are therefore necessary to allow such a refinement.

Numerical Simulation of Residual Stresses during the Heat Treatment of Dies Made of Hot Work Tool Steel

2006 ◽  
Vol 524-525 ◽  
pp. 433-438 ◽  
Author(s):  
Christian Redl ◽  
Christian Friesenbichler ◽  
Volker Wieser
Keyword(s):  
Numerical Simulation ◽  
Heat Treatment ◽  
Residual Stresses ◽  
Phase Distribution ◽  
Production Cycle ◽  
Treatment Model ◽  
The Finite Element Method ◽  
Quenching Media ◽  
Treatment Processes ◽  
Gas Quenching

Residual stresses are of great importance during the entire production cycle of high-grade steels. The use of modern tools based on the finite element method is steadily increasing to optimize heat treatment processes. As for industrial purposes it is often not possible to measure the entire set of material data a sensitivity analysis shows the relative influence of material properties related to phase transformation on the residual stresses during hardening. Subsequently the application of the numerical heat treatment model is shown on two examples: The magnitudes of residual stresses during the quenching of a forged bar in different quenching media are compared. The paper concludes with a numerical simulation of the heat treatment of a die used for extrusion processes. Phase distribution and residual stresses after gas quenching of the tool are presented.

Isothermal treatment of nitrided layers formed on steels

2019 ◽  
Vol 25 (4) ◽  
pp. 34-41
Author(s):  
Piotr Nawrocki ◽  
Jerzy Szawłowski
Keyword(s):  
Heat Treatment ◽  
Cross Sections ◽  
Nitrogen Saturation ◽  
Nitrided Layer ◽  
Isothermal Transformation ◽  
Isothermal Treatment ◽  
Surface Zone ◽  
Austenitizing Temperature ◽  
Treatment Processes ◽  
Different Content

This work was aimed at investigating the formation of nitrided layers during the isothermal transformation (austempering) and at describing the formed nitrided layer properties. The tested steels were characterized by a different content of carbon and alloying elements. In the case of the isothermal transformation, 4 variants of heat treatment parameters of nitrided layers were applied. The heat treatment differed in the austenitizing temperature (750°C–860°C) and the isothermal transformation temperature (390°C- 420°C). The microstructure and the mechanical properties (hardness) of the nitrided layers formed after the heat treatment processes were determined. After the nitriding process, during 30 hours in the nitriding atmosphere consisting only of ammonia, the high nitrogen saturation in the surface zone of the layers was obtained. The nitrided layers, after the heat treatment processes, were char-acterized by the diversified thickness, as evidenced by the hardness distributions at their cross-sections.

Residual Stresses Control for Large Scale Open Die Forged Parts

2016 ◽  
Vol 684 ◽  
pp. 120-126
Author(s):  
Mikhail Hardin ◽  
Sergey Burtsev
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
Large Scale ◽  
Numerical Study ◽  
Fem Simulations ◽  
Simulation Tools ◽  
Quenching Media ◽  
Treatment Processes ◽  
Forged Parts ◽  
Future Work

This paper gives an overview of residual stresses problem after heat treatment of large scale forged parts as well as numerical study and simulations of different methods to reduce stresses. DEFORM software was used for Finite Element Method (FEM) simulations as one of the most capable simulation tools combining both forging and heat treatment processes analysis. The study is performed on the sample of large scale airspace part of aluminum AK6 (AlMgSiCu) alloy. The comparison of different quenching media is presented. Practical conclusions and recommendations are made to optimize the process and reduce residual stresses after the heat treatment. This paper provides numerical simulation and theoretical conclusions and needs to be amended by experimental measurement of residual stresses by one of available methods as part of the future work.

scholarly journals Residual Stress Measurement in Heat Treated Cylindrical Components

2021 ◽  
Author(s):  
M. Belassel ◽  
J. Pineault ◽  
M. Bolla ◽  
M. Brauss
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Microstructural Characterization ◽  
Plain Carbon Steel ◽  
X Ray Diffraction ◽  
Treatment Processes ◽  
Heat Treated ◽  
Xrd Techniques

Abstract Heat treatment processes can generate steep residual stress (RS) gradients and plastic deformation in metal components due to differential cooling and other effect such as phase transformation. The magnitude of residual stresses generated, and how quickly they vary spatially, will depend upon the material itself and the temperature gradients introduced during the heat treatment process. X-ray diffraction (XRD) techniques can be used to characterize residual stresses, as well as microstructural changes, including dislocation density and particle size in heat treated components. Plain carbon steel cylinders were heat treated, quenched and characterized using these methods. Residual stress measurements were performed via XRD using the Sin2Ψ technique and microstructural characterization was evaluated using the associated peak widths. Measurements were carried out both at the surface and through depth using electropolishing. The results indicate triaxial stress gradients exist in all samples investigated, with concomitant varying microstructural characteristics.

Influence of Transformation Plasticity on Residual Stresses and Distortions due to the Heat Treatment of Steels with Different Carbon Content

2005 ◽  
Vol 490-491 ◽  
pp. 47-52 ◽  
Author(s):  
Clemens Franz ◽  
Gerhard Besserdich ◽  
Volker Schulze ◽  
Hermann Müller ◽  
Detlef Löhe
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Treatment Process ◽  
Residual Stress Distribution ◽  
Heat Treatment Process ◽  
Temporal Development ◽  
Transformation Plasticity ◽  
Initial State ◽  
Simulation Tools

The field of heat treatment of steels offers a large variety of applications for the use of simulation tools. It always includes the development of residual stresses and distortions. The geometry of the part, the composition of the material, the heat treatment process as well as the initial state of the part interact with each other in complex ways and have an influence on the distortion of the part. Using simulation the temporal development of temperature, phases, stresses and distortions while quenching as well as the residual stress distribution and distortion after quenching can be calculated. Transformation plasticity has been proved to be very important for heat treatment simulation. Three steels with identical contents of alloying elements but different carbon contents of 0.2, 0.5 and 0.8 wt. % were analysed. The influence of transformation plasticity during the martensitic transformation on the distortions and residual stresses after quenching of cylinders made out of the three steels was analyzed in simulations and compared to experimental results.

Influence of transformation plasticity on residual stresses and distortions due to the heat treatment of steels with different carbon contents

2004 ◽  
Vol 120 ◽  
pp. 481-488
Author(s):  
C. Franz ◽  
G. Besserdich ◽  
V. Schulze ◽  
H. Müller ◽  
D. Löhe
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
Treatment Process ◽  
Manufacturing Processes ◽  
Transformation Plasticity ◽  
Initial State ◽  
Simulation Tools ◽  
Compressive Stresses ◽  
Quenching Process ◽  
Experimental Findings

The simulation of manufacturing processes is more and more becoming an important tool in simultaneous engineering. The aim is to cut the time necessary for development and to optimise processes by simulation of the complete manufacturing chain. The field of heat treatment offers a large variety of applications for the use of simulation tools. Heat treatment of steels always includes the development of residual stresses and distortions. The geometry of the part, the composition of the material, the heat treatment process as well as the initial state of the part interact with each other in complex ways and have an influence on the distortion of the part. Using simulation the temporal development of temperature, phases, stresses and distortions while quenching as well as the residual stress distribution and distortion after quenching can be calculated. Transformation plasticity has been proved to be very important for heat treatment simulation. Three steels with identical contents of alloying elements but different carbon contents of 0.2, 0.5 and 0.8 wt.-% were analysed. The transformation plasticity constants for the martensitic transformation under tensile as well as compressive stresses were determined by quenching hollow specimen with nitrogen. Distortions and residual stresses were examined experimentally with cylinders made out of the three steels. Additionally, simulations of the quenching process of the cylinders were taken into account in the analysis of the experimental findings.

INFLUENCE THE QUENCHING AND TEMPERING ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES AND SURFACE ROUGHNESS, OF MEDIUM CARBON STEEL

2018 ◽  
Vol 18 (1) ◽  
pp. 125-135
Author(s):  
Sattar H A Alfatlawi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Surface Roughness ◽  
Carbon Steel ◽  
Cold Water ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Heating And Cooling ◽  
Treatment Processes ◽  
Quenching And Tempering

One of ways to improve properties of materials without changing the product shape toobtain the desired engineering applications is heating and cooling under effect of controlledsequence of heat treatment. The main aim of this study was to investigate the effect ofheating and cooling on the surface roughness, microstructure and some selected propertiessuch as the hardness and impact strength of Medium Carbon Steel which treated at differenttypes of heat treatment processes. Heat treatment achieved in this work was respectively,heating, quenching and tempering. The specimens were heated to 850°C and left for 45minutes inside the furnace as a holding time at that temperature, then quenching process wasperformed in four types of quenching media (still air, cold water (2°C), oil and polymersolution), respectively. Thereafter, the samples were tempered at 200°C, 400°C, and 600°Cwith one hour as a soaking time for each temperature, then were all cooled by still air. Whenthe heat treatment process was completed, the surface roughness, hardness, impact strengthand microstructure tests were performed. The results showed a change and clearimprovement of surface roughness, mechanical properties and microstructure afterquenching was achieved, as well as the change that took place due to the increasingtoughness and ductility by reducing of brittleness of samples.

Sign in / Sign up

Export Citation Format

Share Document