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.

scholarly journals Microstructural Changes During Short-Term Heat Treatment of Martensitic Stainless Steel—Simulation and Experimental Verification

2021 ◽  
Author(s):  
N. Schmidtseifer ◽  
S. Weber
Keyword(s):  
Heat Treatment ◽  
Martensitic Stainless Steel ◽  
Computer Assisted ◽  
Austenitizing Temperature ◽  
Short Term ◽  
Microstructural Changes ◽  
Martensitic Stainless Steels ◽  
Treatment Processes ◽  
Start Temperature ◽  
Steel Heat

AbstractShort-term heat treatments of steels are used for tools and cutlery but also for the surface treatment of a variety of other workpieces. If corrosion resistance is required, martensitic stainless steels like AISI 420L or AISI 420MoV are typically used. The influence of short-term heat treatment on the different metastable states of the AISI 420L steel was examined and reported in this article. Starting from a defined microstructural state, the influence of a short-term heat treatment is investigated experimentally with the help of a quenching dilatometer and computer assisted simulations are carried out. With the results obtained, a simulation model is built up which allows to compute the microstructural changes during a short-term heat treatment to be evaluated without the need for an experiment. As an indicator, the value of the martensite start temperature is calculated as a function of different holding times at austenitizing temperature. The martensite start temperature is measured by dilatometry and compared to calculated values. Validation of simulated results reveals the potential of optimizing steel heat treatment processes and provides a reliable approach to save time, resources and energy.

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.

Simulation of the Heat Treatment of an Automotive Cast Part

2010 ◽  
Author(s):  
Patrice Lasne ◽  
Mickael Barbelet ◽  
Olivier Jaouen ◽  
Frederic Costes ◽  
Ihab Ragai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Phase Distribution ◽  
Isothermal Transformation ◽  
Shrinkage Porosity ◽  
Hot Tearing ◽  
Water Quenching ◽  
Dump Truck ◽  
Cast Part ◽  
Treatment Processes ◽  
Isothermal Transformation Diagram

In this paper, simulation of the casting and heat treatment processes of front spindle of a rigid dump truck are presented. The objectives are to present how the different operations can be simulated in order to predict the local phases in the different areas of the part. To reach these objectives, two software packages are used in sequenced. The first one, Thercast, is used to simulate the casting operation. The second one, Forge, is applied to the water-quenching simulation. The general formulations used are shortly presented in this paper. The aim of casting simulation is to compute the metal behavior from the liquid state at the pouring stage to the solid state during cooling into the mold. Filling and cooling phases simulations, taking into account the air gap, ensure that no internal defects like shrinkage, porosity, micro porosity or hot tearing are taking place into the part. Forge software allows the water quenching stage simulation. A model is used to deduct the IT diagram (Isothermal Transformation diagram) from the material composition. The initial grain size influences the transformation kinetics. Another main phenomenon is the efficiency of the cooling bath. The results of the simulation (phase distribution, distortion, residual stresses) strongly depend on these input conditions. Thus, the effect of input data variations on final results must be studied. The modeling approach is validated by comparisons with micrographic observations. Another solution to determine the reliability of the models is to observe the local properties in the quenched part. The prediction of the local micro hardness can be used to evaluate the accuracy of the quenching models.

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.

Wear volume prediction of AISI H13 die steel using response surface methodology and artificial neural network

2020 ◽  
Vol 14 (2) ◽  
pp. 6789-6800
Author(s):  
Vishal Jagota ◽  
Rajesh Kumar Sharma
Keyword(s):  
Neural Network ◽  
Heat Treatment ◽  
Artificial Neural Network ◽  
Response Surface ◽  
Sliding Wear ◽  
Austenitizing Temperature ◽  
Tempering Temperature ◽  
Die Steel ◽  
Artificial Neural ◽  
Tempering Time

Resistance to wear of hot die steel is dependent on its mechanical properties governed by the microstructure. The required properties for given application of hot die steel can be obtained with control the microstructure by heat treatment parameters. In the present paper impact of different heat treatment parameters like austenitizing temperature, tempering time, tempering temperature is studied using response surface methodology (RSM) and artificial neural network (ANN) to predict sliding wear of H13 hot die steel. After heat treating samples at austenitizing temperature of 1020°C, 1040°C and 1060°C; tempering temperature 540°C, 560°C and 580°C; tempering time 1hour, 2hours and 3hours, experimentation on pin-on-disc tribo-tester is done to measure the sliding wear of H13 die steel. Box-Behnken design is used to develop a regression model and analysis of variance technique is used to verify the adequacy of developed model in case of RSM. Whereas, multi-layer feed-forward backpropagation architecture with input layer, single hidden layer and an output layer is used in ANN. It was found that ANN proves to be a better tool to predict sliding wear with more accuracy. Correlation coefficient R2 of the artificial neural network model is 0.986 compared to R2 of 0.957 for RSM. However, impact of input parameter interactions can only be analysed using response surface method. In addition, sensitivity analysis is done to determine the heat treatment parameter exerting most influence on the wear resistance of H13 hot die steel and it showed that tempering time has maximum influence on wear volume, followed by tempering temperature and austenitizing temperature. The prediction models will help to estimate the variation in die lifetime by finding the amount of wear that will occur during use of hot die steel, if the heat treatment parameters are varied to achieve different properties.

Effect of Two-step Heat Treatment Processes on the Formation of Protein Particles and Oil Droplets in Soymilk

2020 ◽  
Vol 26 (3) ◽  
pp. 445-450
Author(s):  
Makoto Shimoyamada ◽  
Hironori Shikano ◽  
Shingo Mogami ◽  
Makoto Kanauchi ◽  
Hayato Masuda ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Oil Droplets ◽  
Treatment Processes ◽  
Protein Particles ◽  
Step Heat Treatment

EFFECT ON HARDNESS and MICRO STRUCTURAL BEHAVIOUR OF TOOL STEEL AFTER HEAT TREATMENT PROCESS

2017 ◽  
Vol 4 (24) ◽  
Author(s):  
Karanbir Singh ◽  
Aditya Chhabra ◽  
Vaibhav Kapoor ◽  
Vaibhav Kapoor
Keyword(s):  
Heat Treatment ◽  
Empirical Study ◽  
Tool Steel ◽  
Treatment Process ◽  
Heat Treatment Process ◽  
Structural Behaviour ◽  
Treatment Processes ◽  
En 31

This study is conducted to analyze the effect on the Hardness and Micro Structural Behaviour of three Sample Grades of Tool Steel i.e. EN-31, EN-8, and D3 after Heat Treatment Processes Such As Annealing, Normalizing, and Hardening and Tempering. The purpose of Selecting Tool Steel is Because Tool Steel is Mostly Used in the Manufacturing Industry.This study is based upon the empirical study which means it is derived from experiment and observation rather than theory.

Sign in / Sign up

Export Citation Format

Share Document