Comprehensive Material Characterization for an Intermediate Heat Treatment

2013 ◽  
Vol 549 ◽  
pp. 39-44 ◽  
Author(s):  
Michael Lechner ◽  
Andreas Kuppert ◽  
Marion Merklein
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
New Technologies ◽  
Process Window ◽  
Short Term ◽  
Intermediate Heat Treatment ◽  
Comprehensive Knowledge ◽  
New Strategy ◽  
Two Parameters ◽  
The Impact

Encouraged by increasing climate regulations there is a trend to lightweight constructions in the transportation sector, particularly in the automotive industry. An auspicious possibility to reduce the weight of the vehicle is the substitution of conventional steel by aluminum alloys. However, aluminum has a low formability and therefore new technologies have to be found in order to enhance the materials spectrum of application. A new strategy to extend the process limit is the short-term aluminum intermediate heat treatment between two forming operations. Key idea is the partial adaption of the mechanical properties with a short term heat treatment. By the interaction of soft and hard areas the material flow during the forming operation can be improved and the formability can be enhanced. Prerequisite for a successful application of the technology and the numerical simulation is a comprehensive knowledge about the interaction of pre-straining and a subsequent short term heat treatment. Within this paper the mechanical properties in dependency of the two parameters will be presented and a process window for the heat treatment after first forming operations will be derived. Moreover, the influence of batch fluctuations and the impact of ageing will be demonstrated.

Application of Tailored Heat Treated Blanks under Quasi Series Conditions

2007 ◽  
Vol 344 ◽  
pp. 383-390 ◽  
Author(s):  
Marion Merklein ◽  
Uwe Vogt
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Local Heat ◽  
Strength Distribution ◽  
Process Window ◽  
Short Term ◽  
Forming Process ◽  
Heat Treated ◽  
Set Up ◽  
The Impact

Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank’s local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today’s car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.

Experimental Investigation of Heat-Treated Aluminum Profiles

2015 ◽  
Vol 651-653 ◽  
pp. 59-64
Author(s):  
Marion Merklein ◽  
Matthias Graser ◽  
Michael Lechner
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Experimental Investigation ◽  
Material Flow ◽  
Material Characterization ◽  
Process Window ◽  
Short Term ◽  
Property Distribution ◽  
Heat Treated ◽  
Aluminum Profiles

Tailor Heat Treated Profiles (THTP) are profiles that exhibit local different mechanical properties optimized for a subsequent forming operation. The property distribution is realized by short term heat treatment before a forming operation. Based on the interaction of soft and hard areas the material flow can be improved and the formability can be enhanced. Prerequisite for a successful application of the technology is a comprehensive material characterization. Therefore, within this paper the influence of short term heat treatment on the mechanical properties of profiles will be presented. In particular, different heating technologies based on heat conduction and laser radiation are compared. Based on the results, a process window will be derived. All investigations were performed using the precipitation hardenable aluminum alloy EN AW 6060.

scholarly journals The Effects of Various Conditions of Short-Term Rejuvenation Heat Treatment on Room-Temperature Mechanical Properties of Thermally Aged P92 Boiler Steel

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6076
Author(s):  
Ladislav Falat ◽  
Lucia Čiripová ◽  
Viera Homolová ◽  
Miroslav Džupon ◽  
Róbert Džunda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Toughness ◽  
Room Temperature ◽  
Laves Phase ◽  
Short Term ◽  
Boiler Steel ◽  
P92 Steel ◽  
The Impact

In this work, the effects of various conditions of short-term rejuvenation heat treatment on room-temperature mechanical properties of long-term aged P92 boiler steel were investigated. Normalized and tempered P92 steel pipe was thermally exposed at 600 °C for time durations up to 5000 h in order to simulate high-temperature material degradation, as also occurring in service conditions. Thus, thermally embrittled material states of P92 steel were prepared, showing tempered martensitic microstructures with coarsened secondary phase precipitates of Cr23C6-based carbides and Fe2W-based Laves phase. Compared with the initial normalized and tempered material condition, thermally aged materials exhibited a slight decrease in strength properties (i.e., yield stress and ultimate tensile strength) and deformation properties (i.e., total elongation and reduction of area). The hardness values were almost unaffected, whereas the impact toughness values showed a steep decrease after long-term ageing. An idea for designing the rejuvenation heat treatments for restoration of impact toughness was based on tuning the material properties by short-term annealing effects at various selected temperatures somewhat above the long-term ageing temperature of P92 material. Specifically, the proposed heat treatments were performed within the temperature range between 680 °C and 740 °C, employing variable heating up and cooling down conditions. It was revealed that short-term annealing at 740 °C for 1 h with subsequent rapid cooling into water represents the most efficient rejuvenation heat treatment procedure of thermally aged P92 steel for full restoration of impact toughness up to original values of normalized and tempered material state. Microstructural observations clearly indicated partial dissolution of the Laves phase precipitates to be the crucial phenomenon that played a key role in restoring the impact toughness.

The Effect of Aging Heat Treatment on the Microstructure and Mechanical Properties of 10Cr20Ni25Mo1.5NbN Austenitic Steel

2016 ◽  
Vol 35 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Zhiyuan Liang ◽  
Wanhua Sha ◽  
Qinxin Zhao ◽  
Chongbin Wang ◽  
Jianyong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Austenitic Steel ◽  
Treatment Time ◽  
Aging Treatment ◽  
Secondary Phases ◽  
Aging Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
The Impact

AbstractThe effect of aging heat treatment on the microstructure and mechanical properties of 10Cr20Ni25Mo1.5NbN austenitic steel was investigated in this article. The microstructure was characterized by scanning electron microscopy, energy dispersive spectrometry and transmission electron microscopy. Results show that the microstructure of 10Cr20Ni25Mo1.5NbN austenitic is composed of austenite. This steel was strengthened by precipitates of secondary phases that were mainly M23C6 carbides and NbCrN nitrides. As aging treatment time increased, the tensile strength first rose (0–3,000 h) and then fell (3,000–5,000 h) due to the decrease of high density of dislocations. The impact absorbed energy decreased sharply, causing the sulfides to precipitate at the grain boundary. Therefore, the content of sulfur should be strictly controlled in the steelmaking process.

A Multi-Criteria Simulation Framework for Civil Aircraft Trajectory Optimisation

2010 ◽  
Author(s):  
Hasan Zolata ◽  
Cesar Celis ◽  
Vishal Sethi ◽  
Riti Singh ◽  
David Zammit-Mangion
Keyword(s):  
Computational Models ◽  
New Technologies ◽  
Oxides Of Nitrogen ◽  
Simulation Framework ◽  
Short Term ◽  
Commercial Aviation ◽  
Flight Profile ◽  
Aircraft Trajectory ◽  
The Impact ◽  
Trajectory Optimisation

Over the past few years, great concern has been raised about the impact of commercial aviation on the environment. In a Business As Usual approach, the expected growth in air traffic is going to affect climate change even more unless mitigation policies are devised and implemented. Although there is a tendency to focus on long-term technological solutions and breakthroughs, short-term improvements applicable to existing aircraft/engine configurations are also very important to fully realise the benefits of new technologies. Aircraft trajectory optimisation presents the opportunity to effectively reduce fuel consumption and pollutants emitted providing a feasible short-term strategy to be applied to the existing aircraft fleet. The present study focuses on preliminary results obtained using a multi-disciplinary aircraft trajectory optimisation simulation framework. Three in-house computational models are implemented in the framework to model the aircraft and engine performance, as well as to predict the level of gaseous emissions produced. A commercially available optimiser is integrated within the framework to analyse and optimise single flight path elements (e.g., climb), as well as the entire flight profile. For the purpose of this study, the climb and the whole flight profile are divided in four and eight segments respectively. Trajectory optimisation processes are then carried out in order to minimise three different objective functions: flight time, fuel burned, and mass of oxides of nitrogen (NOx) emitted. The results of the trajectory optimisation processes performed confirm the validity, effectiveness, and flexibility of the methodology proposed. In future, it is expected that these types of approaches are utilised to efficiently compute complete, optimum and ‘greener’ aircraft trajectories, which help to minimise the impact of commercial aviation on the environment. Other computational models that simulate several other aspects such as aircraft and engine noise, weather conditions and contrails formation, among others, need to be also included in the optimisation processes.

Influence of the conditions of casting and heat treatment on the structure and mechanical properties of the AlMg10 alloy

2017 ◽  
Vol 1 (83) ◽  
pp. 26-32
Author(s):  
P. Kordas
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Liquid State ◽  
Precipitation Hardening ◽  
Solidification Rate ◽  
Dendritic Structure ◽  
Grain Structure ◽  
Alloy Castings ◽  
Die Castings ◽  
The Impact

Purpose: Assessment of the possibilities of shaping the structure and improvement of mechanical properties of casting from AlMg10 alloy through a selection of casting technology and precipitation hardening. Design/methodology/approach: the work evaluated the impact of casting and heat treatment technology on the mechanical properties and structure of AlMg10 alloy castings. The tests were performed on 200 mm × 100 mm × 25 mm plate castings produced by gravity casting methods for sand and metal moulds and by a liquid state press moulding technology. Castings made with these technologies solidify in substantially different heat- evaporation conditions and exhibit varying degrees of primary structure fragmentation. Metallographic and strength tests were performed on raw castings and after heat treatment. Findings: The changes in the morphology and size of primary crystals and the dispersion of the reinforcing phase according to the casting solidification rate and the precipitation hardening treatment were analyzed. Solidifying castings in the form of sand show a globular structure, whereas in die and press castings, a typically dendritic structure occurs, with the dendritic crystals in pressed castings being much smaller in size than the die castings. In castings which were not heat-treated, the reinforcing phase of Al3Mg2 occurs in interdendritic spaces, and its dispersion increases with the rate of cooling. After supersaturation and ageing treatments, the phase α has a grain structure in all samples. The largest dispersion of reinforcing molecules is characterized by press castings. In a raw state, the highest mechanical properties are shown by castings made in the form of sand and the method of pressing in a liquid state. Heat treatment of AlMg10 alloy castings significantly influences the increase of mechanical indexes in all castings investigated. The highest features of Rm are approx. 330 MPa and A5 above 10% is obtained in castings made by the press method. Research limitations/implications: Particular attention should be paid to the avoidance of the effects of slag inclusion, shrinkage and magnesium oxidation during casting of AlMg10 alloys. In die castings of a plate type, due to own stresses, a significant decrease in mechanical properties occurs. Practical implications: The most advantageous mechanical properties of AlMg10 alloy castings are obtained by using liquid-state pressing technology. In addition, this technology makes it possible to produce thin-walled castings of high dimensional accuracy, high air- tightness, fine grain structure, lack of surface defects and low roughness. Originality/value: The paper presents the possibility of improving the mechanical properties of AlMg10 castings by applying heat treatment. It has been proven that the casting method has a significant effect on the mechanical properties of the castings.

Effect of Heat Treatment Hardness of Al-Cu-Mg-Li-Zr, Al-Mg-Si and and Al-Mg-Zn Alloys-Experimental Correlation Using Factorial DOE and ANOVA Methods

2014 ◽  
Vol 881-883 ◽  
pp. 1317-1329 ◽  
Author(s):  
Mahmoud M. Tash ◽  
Saleh Alkahtani
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cold Work ◽  
Solution Treatment ◽  
Statistical Design ◽  
Aging Treatment ◽  
Fractional Factorial ◽  
Statistical Design Of Experiments ◽  
The Impact ◽  
Zn Alloys

The present study was conducted to investigate the effect of heat treatment on the aging and mechanical behavior of Al-Cu-Mg-Li-Zr , Al-Mg-Si and and Al-Mg-Zn alloys (8090 , 6082 and 7075). The effect of cold work after solution treatment, aging parameters (time and temperature) on the microstructure and mechanical properties were studied. Attempts are made to determine the combined effect of cold work and aging treatment on the hardness, UTS and microstructure for these alloys. By study the impact of different heat treatments for Al-Mg-Si alloys (6082), Al-Cu-Mg-Li-Zr (8090) and Al-Mg-Zn (7075) aluminum alloys on the hardness and mechanical properties, it is possible to determine conditions necessary to achieve better mechanical properties and the maximum levels of hardness and values corresponding to those considered suitable for commercial applications of these alloys.Design of Experiment (DOE) method in Minitab is used to measure the impact of various factors and how they relate. Correlation between the hardness and different metallurgical factors for these alloys at both quantitative and qualitative are investigated and analysed. A statistical design of experiments (DOE) approach using fractional factorial design was applied to determine the influence of controlling variables of cold work and heat treatment parameters and any interactions between them on the hardness of the above alloys. A mathematical model is developed to relate the alloy hardness with the different metallurgical parameters to acquire an understanding of the effects of these variables and their interactions on the hardness of wrought Al-alloys. It is noticed that cold work, following solution treatment, accelerates the precipitation rate leading to a rise in strength

The Influence of Boron on Structure and Mechanical Properties of Bainite Ductile Iron in the Step Austempering in Room Temperature Machine Oil

2010 ◽  
Vol 139-141 ◽  
pp. 235-238
Author(s):  
De Qiang Wei
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Iron ◽  
Impact Strength ◽  
Ductile Iron ◽  
Room Temperature ◽  
Solute Drag ◽  
Ductile Cast Iron ◽  
Treatment Technique ◽  
The Impact

In this paper, the low alloy bainite ductile cast iron has been obtained by a new heat treatment technique of the step austempering in room-temperature machine oil. The effects of element boron, manganese and copper on structure and mechanical properties of the bainite ductile cast Iron in above-mentioned process are investigated. The phenomenon, hardness lag of the alloyed bainite ductile cast Iron, has been discussed. It shows that after the step austempering in room-temperature machine oil, the hardness will increases with the time. It is found that boron and manganese can increase the hardness and reduce the impact strength while copper can increase the impact strength. The results show that reasonable alloyed elements can improve mechanical properties of the bainite ductile cast Iron. Essentially, hardness lag of the alloyed bainite ductile cast Iron is resulted from solute drag-like effect.

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