scholarly journals Investigation of a partial, inductive short-time heat treatment of thin metal sheets integrated into the forming process

2018 ◽  
Vol 190 ◽  
pp. 12008
Author(s):  
Benjamin Clausius ◽  
Petra Maier
Keyword(s):  
Heat Treatment ◽  
Strain Hardening ◽  
Sheet Thickness ◽  
Local Strain ◽  
Single Step ◽  
Thin Metal ◽  
Recrystallization Annealing ◽  
Forming Process ◽  
Metal Sheets ◽  
Short Time

Flanging is a widespread method in the sheet metal working industry to connect same or different materials by forming. Especially the sealing technology makes high demands on the flanging process: a low sheet thickness of the inner eyelet is necessary for proper sealing. The outer edges of the neck rings are mostly manufactured by shear cutting. The quality of the cut surface and the level of the local strain hardening influence decisively the limit of the flanging process by possible cracking. This paper is focused on the dependencies of these factors regarding thin metal sheets of different materials with a thickness down to 100 μm. It could be shown that strain hardening has a stronger effect on the process limits compared to the notch effect of the sheet edges when using standard values for the clearance of the shear cutting tool. Furthermore, a process is investigated with a partial inductive short-time heat treatment of the most deformed edge area. Due to the low thickness of the material and low heat capacities related thereto, it is possible to integrate a recrystallization annealing as single step into the forming process. As a result, the strain hardening can be removed from the affected zone directly between two forming steps to increase the process limits.

scholarly journals Investigations on the Hot Stamping of AW-7921-T4 Alloy Sheet

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
M. Kumar ◽  
N. G. Ross
Keyword(s):  
Heat Treatment ◽  
Hot Stamping ◽  
Alloy Sheet ◽  
Single Step ◽  
Forming Process ◽  
Scanning Calorimetry ◽  
Weighting Potential ◽  
7Xxx Alloy ◽  
Increasing Temperature ◽  
Rate Dynamic

AW-7xxx alloys have been nowadays considered for greater light weighting potential in automotive industry due to its higher strength compared to AW-5xxx and AW-6xxx alloys. However, due to their lower formability the forming processes are still in development. This paper investigates one such forming process called hot stamping. The investigation started by carrying out hot tensile testing of an AW-7xxx alloy, that is, AW-7921 at temperatures between 350°C and 475°C, to measure the strength and formability. Formability was found to improve with increasing temperature and was sensitive to the strain rate. Dynamic recovery is considered as usual reason for the formability improvement. However, examining the precipitation states of the as-received condition and after hot stamping using differential scanning calorimetry (DSC), the dissolution of precipitates was also believed to contribute to this increase in formability. Following solution heat treatment there was no precipitation during cooling across the cooling rates investigated (5–10°C/s). Samples taken from parts hot stamped at 10 and 20 mm s−1 had similar yield strengths. A 3-step paint baking heat treatment yielded a higher postpaint baking strength than a single step treatment.

Investigation of the Strain Hardening and Bauschinger Effect of Low and High Strength Steel Application in Drawbead-Tester by Experiment and Numerical Simulation

2008 ◽  
Vol 55-57 ◽  
pp. 761-764
Author(s):  
K. Sirivedin ◽  
K. Krueger ◽  
V. Thoms ◽  
Dietmar Suesse ◽  
Roland Mueller ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Strain Hardening ◽  
Sheet Metal ◽  
Bauschinger Effect ◽  
Strain Analysis ◽  
High Strength ◽  
Local Strain ◽  
Simulation Method ◽  
Forming Process ◽  
Three Point Bending

The research is aimed to investigate Bauschinger effect and strain hardening by the application of drawbead-tester. Generally, the drawbead is used to control the material flow into the die cavity in sheet metal forming process. When the material is flowing into the drawbead, it may cause the development of strain hardening and/or Bauschinger effect. This work consists of two main equipment particularly developed for the experiments. They are drawbead-tester and three-point bending device. The drawbead-tester provides the possibility to integrate the optical in-process strain analysis system. Whereas the sheet metal was being formed in the drawbead, the local strain of the sheet metal was evaluated. At the same time, the drawbead restraining and holding forces were measured. The three point bending device and numerical simulation method are used to investigate the Bauschinger effect. In the experiment, the cyclic bending forces were measured and compared with the result obtained by numerical simulation.

Effect of a Complex Heat Treatment on the Structure of 300M Steel

1981 ◽  
Vol 39 ◽  
pp. 312-313
Author(s):  
R. Padmanabhan ◽  
W. E. Wood
Keyword(s):  
Heat Treatment ◽  
Metal Carbides ◽  
Austenite Grain Size ◽  
300M Steel ◽  
Heat Treated ◽  
Strain Fracture ◽  
Prior Austenite Grain Size ◽  
Short Time ◽  
Final Tempering ◽  
Similar Yield

Intermediate high temperature tempering prior to subsequent reaustenitization has been shown to double the plane strain fracture toughness as compared to conventionally heat treated UHSLA steels, at similar yield strength levels. The precipitation (during tempering) of metal carbides and their subsequent partial redissolution and refinement (during reaustenitization), in addition to the reduction in the prior austenite grain size during the cycling operation have all been suggested to contribute to the observed improvement in the mechanical properties. In this investigation, 300M steel was initially austenitized at 1143°K and then subjected to intermediate tempering at 923°K for 1 hr. before reaustenitizing at 1123°K for a short time and final tempering at 583°K. The changes in the microstructure responsible for the improvement in the properties have been studied and compared with conventionally heat treated steel. Fig. 1 shows interlath films of retained austenite produced during conventionally heat treatment.

scholarly journals Study on strong spinning preparation method and mechanism of the industrial pure titanium ultrafine crystallization

2019 ◽  
Vol 14 ◽  
pp. 155892501989525
Author(s):  
Yu Yang ◽  
Yanyan Jia
Keyword(s):  
Heat Treatment ◽  
High Performance ◽  
Pure Titanium ◽  
Grain Structure ◽  
Theoretical Research ◽  
Ultrafine Grain ◽  
Forming Process ◽  
Spinning Process ◽  
And Performance ◽  
Material Utilization

Ultrafine crystallization of industrial pure titanium allowed for higher tensile strength, corrosion resistance, and thermal stability and is therefore widely used in medical instrumentation, aerospace, and passenger vehicle manufacturing. However, the ultrafine crystallizing batch preparation of tubular industrial pure titanium is limited by the development of the spinning process and has remained at the theoretical research stage. In this article, the tubular TA2 industrial pure titanium was taken as the research object, and the ultrafine crystal forming process based on “5-pass strong spin-heat treatment-3 pass-spreading-heat treatment” was proposed. Based on the spinning process test, the ultimate thinning rate of the method is explored and the evolution of the surface microstructure was analyzed by metallographic microscope. The research suggests that the multi-pass, medium–small, and thinning amount of spinning causes the grain structure to be elongated in the axial and tangential directions, and then refined, and the axial fiber uniformity is improved. The research results have certain scientific significance for reducing the consumption of high-performance metals improving material utilization and performance, which also promote the development of ultrafine-grain metals’ preparation technology.

Single-layer submicron-thick BaTiO3 coatings from poly(vinylpyrrolidone)-containing sols: Gel-to-ceramic film conversion, densification, and dielectric properties

2001 ◽  
Vol 16 (11) ◽  
pp. 3116-3123 ◽  
Author(s):  
Hiromitsu Kozuka ◽  
Atsushi Higuchi
Keyword(s):  
Heat Treatment ◽  
Condensation Reaction ◽  
Single Layer ◽  
Dip Coating ◽  
Single Step ◽  
Dielectric Constants ◽  
Isothermal Heat Treatment ◽  
Coating Films ◽  
Ceramic Film ◽  
C Decomposition

BaTiO3-coating films were prepared from a solution containing poly(vinylpyrrolidone) (PVP) of molar composition Ba(CH3COO)2:Ti(OC2H5)4:PVP:CH3COOH:H2O: C2H5OH = 1:1:0.5:27:4:5, via nonrepetitive, single-step dip-coating. The gel films were found to be converted into BaTiO3 films via evaporation of the solvent and CH3COOH below 210 °C, decomposition of PVP at 210–360 °C, decomposition of CH3COO− below 440 °C, and crystallization at 500–610 °C. The decomposition of PVP was accompanied by the progress of the condensation reaction, which resulted in significant reduction in film thickness. When the gel films were heated isothermally at 700 °C, crack-free BaTiO3 films as thick as 0.9 μm were obtained. When the gel films were heated isothermally at 360 °C and then at 700 °C, the film became denser. Higher dielectric constants around 290 were found for the film that underwent the isothermal heat treatment at 360 °C. A slower rate of PVP decomposition was thought to be the key for the film densification.

Short-time heat treatment of press hardened steel for laser assisted clinching

2014 ◽  
Vol 30 (11) ◽  
pp. 1287-1296 ◽  
Author(s):  
M. Reich ◽  
J. Osten ◽  
B. Milkereit ◽  
J. Kalich ◽  
U. Füssel ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hardened Steel ◽  
Short Time

Facile single-step ammonia heat-treatment and quenching process for the synthesis of improved Pt/N-graphene catalysts

2013 ◽  
Vol 266 ◽  
pp. 433-439 ◽  
Author(s):  
Bin Xiong ◽  
Yingke Zhou ◽  
Ryan O’Hayre ◽  
Zongping Shao
Keyword(s):  
Heat Treatment ◽  
Single Step ◽  
Quenching Process

On the Influence of a Heat Treat for an Aluminizing Progress Based on Al Microparticles Slurry for Model Ni and Ni20Cr. Experimental and Theoretical Approaches.

2012 ◽  
Vol 323-325 ◽  
pp. 373-379 ◽  
Author(s):  
B. Rannou ◽  
M. Mollard ◽  
B. Bouchaud ◽  
J. Balmain ◽  
G. Bonnet ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Substrate Surface ◽  
Single Step ◽  
Alloying Element ◽  
Aluminum Particles ◽  
New Approach ◽  
Theoretical Approaches ◽  
Barrier Coating ◽  
Coating Characteristics ◽  
Good Agreement

The use of thermal barrier coating systems allows superalloys to withstand higher operating temperatures in aeroengine turbines. Aiming at providing oxidation protection to such substrates, an aluminum-rich layer is deposited to form the α-Al2O3scale over which a ceramic layer (i.e. YSZ layer) is applied to provide thermal insulation. A new approach is now being investigated within the FP7 European project « PARTICOAT », in which a single step process is employed by applying micro-sized aluminum particles. The particles are mixed in a binder and deposited by brushing or spraying on the substrate surface. During a heat treatment, the particles sinter and oxidize to form a top coat composed of hollow con-joint alumina spheres and simultaneously, an Al-rich diffusion zone is formed in the substrate. For a better understanding of the diffusion / growth processes, preliminary tests were carried out on pure nickel and Ni20Cr model alloys prior to further application on commercial superalloys. The effect of the heat treatment on the coating characteristics (number of layers, thickness, composition, homogeneity, etc.) was particularly investigated to emphasize the mechanisms of diffusion governing the growth of the coatings. The establishment of the diffused layers occurred very readily even at intermediate temperatures (650 and 700°C). However, the layers formed did not match perfectly with the thermodynamic modeling because of the quick incorporation of Ni into molten Al at intermediate temperatures (650°C). In contrast, at higher temperatures (700 and 1100°C) the phases predicted by Thermocalc are in good agreement with the observed thickness of the diffused layers. The incorporation of Cr as an alloying element restrained Al ingress by segregation of Cr even at very low temperatures aluminizing temperatures (625°C).

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.

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