scholarly journals Densification Mechanism for the Precursor of AFS under Different Rolling Temperatures

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3933 ◽  
Author(s):  
Xi Sun ◽  
Peng Huang ◽  
Xiaoguang Zhang ◽  
Nanding Han ◽  
Jinqin Lei ◽  
...  
Keyword(s):  
Rolling Direction ◽  
Core Layer ◽  
Rolling Temperature ◽  
Densification Mechanism ◽  
Micro Cracks ◽  
Micro Holes ◽  
Powder Particles ◽  
Room Temperature Rolling ◽  
Core Powder ◽  
Rolling Temperatures

The effect of rolling temperature on the precursor of aluminum foam sandwich (AFS) prepared by powder metallurgy through Pack Rolling method is investigated in this work. The cross-section along rolling direction of the precursors was observed. It was found that periodic corrugated morphology with micro-cracks on the composite interface as well as cracks and micro-holes among core powder particles emerged abundantly at room temperature rolling. These defects degraded with increasing rolling temperature and completely disappeared when the rolling temperature reached 400 °C. Combining with foaming ability of these precursors, the densification mechanism of core powders was discussed. Powder particles deformed with difficulty at low rolling temperature; the gap between them cannot be effectively filled through their plastic deformation. Fracture occurred in powder core layer during co-extension with the outer panel and was partly embedded by it, resulting in corrugated composite morphology at the interface. The precursors of high density and excellent bonding interface were prepared at the rolling temperature of 400 °C. A more suitable foaming condition was determined.

scholarly journals Selective Anisotropy of Mechanical Properties in Inconel718 Alloy

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3869
Author(s):  
Yu Liang ◽  
Jun Ma ◽  
Baogang Zhou ◽  
Wei Li
Keyword(s):  
Solid Solution ◽  
Crack Nucleation ◽  
Rolling Direction ◽  
Mechanical Anisotropy ◽  
Solution Temperature ◽  
Weak Anisotropy ◽  
Nucleation Sites ◽  
Micro Cracks ◽  
Δ Phase ◽  
Rupture Properties

Mechanical anisotropy behaviors are investigated in slightly rolled Inconel718 alloy with string-like δ phase and carbides produced during various solid-solution and aging treatments. A weak anisotropy in the strengths and rupture properties at 650 °C is visible, whereas ductility, i.e., reduction in area (RA) and impact toughness (CVN), presents a sound anisotropy behavior. MC carbides promote the operation of slip systems and thus are conducive to weakening the strength anisotropy. The RA anisotropy mainly stems from high-density δ phase particles that provide more crack nucleation sites and stimulate rapid propagation because of the shorter bridge distance between micro-cracks at the rolling direction. In contrast, CVN anisotropy arises from both δ phase and carbides at a lower solid-solution temperature of 940 °C but only depends on carbides at 980 °C where the δ phase fully dissolves. Apart from dislocation motions operated at room temperature, the activated grain boundary processes are responsible for the weak anisotropy of rupture properties at the elevated temperature. This work provides a guideline for technological applications in the hot working processes for Inconel718 alloys.

Study on the Microstructure and Texture of Warm Rolled ZK60 Magnesium Alloy Sheet

2012 ◽  
Vol 557-559 ◽  
pp. 1344-1348
Author(s):  
Hong Mei Chen ◽  
Hua Shun Yu ◽  
Guang Hui Min ◽  
Yun Xue Jin
Keyword(s):  
Shear Bands ◽  
Rolling Direction ◽  
Rolling Process ◽  
Warm Rolling ◽  
Alloy Sheet ◽  
Rolling Temperature ◽  
Rolling Reduction ◽  
Basal Pole ◽  
Zk60 Alloy ◽  
Twin Roll

The microstructure and macrotexture of ZK60 alloy sheet were investigated through OM and XRD, which were produced by twin roll casting and sequential warm rolling. Microstructure of twin roll cast ZK60 alloy changed from dendrite structure to fibrous structure with elongated grains and high density shear bands along the rolling direction after warm rolling process at different rolling parameters. The density of shear bands increased with the decreasing of the rolling temperature, or the increasing of per pass rolling reduction. Dynamic recrystallization could be found during the warm rolling process at and above 350oC, and many fine grains could be found in the shear band area. The warm rolled ZK60 alloy sheet exhibited strong (0001) basal pole texture. The formation of the shear bands tends to cause the basal pole tilt slightly to the transverse direction after warm rolling. The intensity of (0001) pole figure increased with the decreasing of rolling temperature, or the increasing of per pass rolling reduction.

The Effect of Rolling Temperature on Grain Size and Toughness in Hot Rolled Q345E H-Beam Steel

2018 ◽  
Vol 279 ◽  
pp. 26-29
Author(s):  
Li Ping Sun ◽  
Guo Hui Zhu ◽  
Jun Xing ◽  
Qi Wei Chen
Keyword(s):  
Grain Size ◽  
Rolling Temperature ◽  
Experimental Results ◽  
Average Grain Size ◽  
H Beam ◽  
Rolling Temperatures ◽  
Hot Rolled

The effect of enter rolling temperatures on the grain size and toughness was investigated in Q345E H-beam steels. The experimental results shown that the grain size exhibited a complicated phenomenon with rolling temperature instead of refining as the temperature decreased as expected. It would be interpreted by the behaviors of deformation and recrystallization in austenite during rolling. The toughness is not only depended on the average grain size but also on the distribution of grain size as well as morphology of pearlite. The toughness would be decreased by the mixed grain size.

scholarly journals Influence of Rolling Temperatures on Interface Microstructure and Mechanical Properties of Multi-Pass Rolling TA1/Q235B Explosive Welded Sheets

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1654
Author(s):  
Huizhong Li ◽  
Liangming Cao ◽  
Xiaopeng Liang ◽  
Wending Zhang ◽  
Chunping Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Strength ◽  
Hot Rolling ◽  
Transition Layer ◽  
Rolling Temperature ◽  
Rolled Sheet ◽  
Interface Microstructure ◽  
Microstructure And Mechanical Properties ◽  
Rolling Temperatures

The effect of rolling temperatures on the interface microstructure and mechanical properties is investigated using 2-mm-thick TA1/Q235B composite sheets, which were prepared after nine passes of hot rolling of explosive welded plates. The results show that the vortex region and the transition layer exist in the interface at the explosive welded plate, while only the transition layer exists in the interface after hot rolling. The transition layer is composed of α-Ti, TiC, Fe, and FeTi, and the thickness increases with the increasing rolling temperature. The microhardness of the explosive welded plate is higher than that of the hot-rolling sheet, and the microhardness of interface are higher than that of matrix metals. The interface shear strength and tensile elongation of the hot-rolled sheet increase with the increasing hot rolling temperature, while the ultimate tensile strength (UTS), yield strength (YS) and Young modulus decrease with the increase of hot rolling temperature. The shear strength of sheets is related to the interfacial compounds, and the tensile strength is mainly affected by the grain morphology of the matrix.

Effect of Rolling Temperature, Reduction and Alloying Additions on the Texture of Warm Rolled Steels

2005 ◽  
Vol 495-497 ◽  
pp. 501-506 ◽  
Author(s):  
M. Sánchez-Araiza ◽  
Stéphane Godet ◽  
John J. Jonas
Keyword(s):  
Cold Rolling ◽  
Heating Rate ◽  
Warm Rolling ◽  
Carbon Steels ◽  
Rolling Temperature ◽  
Rolling Reduction ◽  
Low Carbon ◽  
Cold Rolling Reduction ◽  
Noticeable Improvement ◽  
Rolling Temperatures

The effect of warm and cold rolling parameters on the development of annealing textures was studied in two low carbon steels containing additions of chromium. Two warm rolling temperatures (640 and 700°C) were employed together with a reduction of 65%. The effects of an additional cold rolling reduction of 40% and of decreasing the heating rate during annealing were also studied. The ND fiber, <111>//ND, of the recrystallization texture was strengthened as the warm rolling temperature was decreased. However, all the warm rolled steels contained a retained RD fiber, <110>//RD. A noticeable improvement in both the continuity and intensity of the ND fiber was obtained when the sample was submitted to an additional 40% cold rolling reduction. The ND fiber was even more continuous and intense when a low heating rate was utilized, yielding r-values of 1.1 and 1.3 for the warm rolled and warm plus cold rolled samples, respectively.

Rolling Temperature and Subsequent Annealing on Microstructure, Texture and Mechanical Properties of Consecutive Rolled Mg-2.0Zn-0.8Gd Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 369-376 ◽  
Author(s):  
Hong Yan ◽  
Rong Shi Chen ◽  
En Hou Han
Keyword(s):  
Mechanical Properties ◽  
Dynamic Recrystallization ◽  
Transverse Direction ◽  
Rolling Direction ◽  
Annealing Process ◽  
Normal Direction ◽  
Rolling Temperature ◽  
Rolled Sheet ◽  
Basal Texture ◽  
Different Temperatures

Mg-2.0Zn-0.8Gd (wt. %) alloy was rolled consecutively at different temperatures. The influence of rolling temperature and annealing process on the microstructure, texture and mechanical properties of the sheet were investigated. A deformation microstructure consisting of many intersected twins and a few dynamic recrystallization grains, and a basal texture with basal poles tilting about ± 10-15° from the normal direction towards the rolling direction were observed in the as-rolled sheet after 4 consecutive rolling processes. Static recrystallizaiton took place in the sheet after annealed above 300 °C. The annealed sheet exhibited a uniform microstructure and a non-basal texture with basal poles tilting about ± 38-43° from the normal direction towards the transverse direction. The annealed sheets exhibited higher ductility about 32% along the rolling direction and 40% along the transverse direction comparing with the as-rolled sheets. The static recrystallization during annealing process was helpful to modify the texture as well as the dynamic recrystallization during rolling in the RE-containing alloys.

Influences of Rolling Conditions on Texture and Mechanical Properties of AZ31 Magnesium Alloy Processed by Differential Speed Rolling

2007 ◽  
Vol 561-565 ◽  
pp. 287-290
Author(s):  
Kazutaka Suzuki ◽  
Xin Sheng Huang ◽  
Akira Watazu ◽  
Ichinori Shigematsu ◽  
Naobumi Saito
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Rolling Direction ◽  
Rolling Temperature ◽  
Az31 Magnesium Alloy ◽  
Speed Ratio ◽  
Shear Direction ◽  
Differential Speed Rolling ◽  
Press Formability ◽  
Differential Speed

It was reported that the cold and warm press formability of the magnesium alloy was improved by the application of a differential speed rolling (DSR). However, it can be considered that the microstructure and the texture of the DSR processed sheets greatly change with the rolling conditions. In this study, commercial AZ31B magnesium alloy extrusions were processed by DSR at a differential speed ratio of 1.167 and a reduction per pass of 10% or less, and the effects of the rolling temperature, the number of rolling passes and reversal of the rolling direction on texture and mechanical properties were examined. As a result, it was found that the optimal rolling temperature in terms of the workability and formability of the material was 573 K. And the elongation and formability were maximal in sheets processed by 4–6 passes of DSR. Moreover, reversing the shear direction made the microstructure more homogeneous and finer than unidirectional shear, and improved the mechanical properties and formability. This improvement was greater in samples where the shear direction was reversed once in the middle than where it was reversed for each pass.

Study of Inner Micro Cracks on Rolling Contact Fatigue of Bearing Steels Using Ultrasonic Nano-Crystalline Surface Modification

2011 ◽  
Vol 462-463 ◽  
pp. 979-984 ◽  
Author(s):  
Chang Soon Lee ◽  
In Shik Cho ◽  
Young Shik Pyoun ◽  
In Gyu Park
Keyword(s):  
Surface Modification ◽  
Rolling Contact Fatigue ◽  
Rolling Direction ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Fatigue Lifetime ◽  
Bearing Steels ◽  
Nano Crystalline ◽  
Micro Cracks ◽  
Crystalline Surface

The purpose of this study is to analyze the effect of ultrasonic nano-crystalline surface modification (UNSM) treatment on rolling contact fatigue (RCF) characteristics of bearing steels. It was found that severe plastic deformation occurred at surface by over 100 µm after UNSM treatment. The micro surface hardness was increased by 18%, and the measured compressive residual stress was as high as -700~-900MPa. The polymet RCF-2 roller type RCF test showed over 2 times longer fatigue lifetime after UNSM treatment under Hertzian contact stress of 425.2kg/mm2 and 8,000 rpm. And SEM study showed a spalling phenomenon at the samples which went through the RCF test after UNSM treatment. Samples before UNSM treatment produced surface initiated spalls and multi shear lips by progressive spalling at the end along the rolling direction, but sub-surface initiated spalls were formed without multi shear lips after UNSM treatment. The spalling occurred at once, and the size and depth of spalls were larger than those before UNSM treatment. And micro cracks were found to form within the spallings after UNSM treatment, and stress distribution at the maximum Herzian shear stress through these micro cracks is thought to improve the fatigue lifetime of bearing materials.

Machining and Characterization of Deep Micro Holes on Super Alloy Processed by Millisecond Pulsed Laser

2016 ◽  
Vol 703 ◽  
pp. 34-38 ◽  
Author(s):  
Yun Long Wang ◽  
Lin Zhong Zhu ◽  
Cai Yan Chen ◽  
Zhi Chen Liu ◽  
Wei Xin Ren ◽  
...  
Keyword(s):  
Laser Power ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Processing System ◽  
Longitudinal Section ◽  
Recast Layer ◽  
Numerical Control ◽  
Micro Cracks ◽  
Micro Holes ◽  
Super Alloy

In this study, a series of deep micro holes were machined on thick GH4169 super alloy by the trepan drilling, using a millisecond pulsed laser which equipped to the numerical control processing system. The microstructure of the holes including surface and longitudinal morphologies, diameter, taper, circularity, micro cracks and recast layer were systematically characterized. The surface morphology and the longitudinal section of the drilled holes were observed by Scanning Electron Microscope and 3D Laser Scanning Confocal Microscope. The method of Minimum circumcircle method was employed to evaluate the entrance and exit end circularity. The results showed that the melt and spattering accumulating around the holes decreased with the augment of laser power. The diameter of the entrance showed an increasing tendency with the growing of laser power, but the exit end was not seriously affected by the power. The micro cracks and recast layer could be found obviously, the micro cracks appeared in those zones which thermal stress concentrated, the thickness of recast layer is about 20μm and the taper and circularity were optimized at a laser power of 80-100W.

Laboratory Controlled Rolling of Microalloyed Steel for Production of Seamless Tubes

2016 ◽  
Vol 258 ◽  
pp. 611-614 ◽  
Author(s):  
Petr Kawulok ◽  
Radek Jurča ◽  
Ivo Schindler ◽  
Stanislav Rusz ◽  
Rostislav Turoň ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Hsla Steel ◽  
Tensile Tests ◽  
Strength Properties ◽  
Controlled Rolling ◽  
Rolling Temperature ◽  
Plastic Properties ◽  
Finish Rolling Temperature ◽  
Finish Rolling ◽  
Rolling Temperatures

Using the laboratory rolling mill with smooth rolls, piercing, as well as rolling in a pilger mill of the seamless tubes with diameter 273 mm from the HSLA steel microalloyed with vanadium steel was simulated. Influence of the wall thickness (6.3 – 40 mm) and finish rolling temperature on the final structural and mechanical properties was investigated. Necessary temperatures of the phase transformations in the course of cooling were determined by dilatometric tests. Based on the dilatometry results, finish rolling temperatures were reduced. Lower rolling temperatures yielded in a relative grain refinement. Effect of the finish rolling temperature did not have any marked impact on the tensile tests results. Strength properties decreased only slightly with the increasing wall thickness and the plastic properties were not influenced significantly by this parameter. The positive effect of the reduced finishing temperature appeared markedly in the results of impact tests performed at room temperature only. Notch toughness was increased by approx. 25 % in the case of the wall thickness of not less than 20 mm.

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