Detection of Quench Induced Precipitation in Al Alloys by Dilatometry

2016 ◽  
Vol 877 ◽  
pp. 147-152 ◽  
Author(s):  
Benjamin Milkereit ◽  
Michael Reich ◽  
Olaf Kessler
Keyword(s):  
Cooling Rate ◽  
High Strength ◽  
Al Alloys ◽  
Age Hardening ◽  
Controlled Cooling ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
Precipitation Behaviour ◽  
In Situ Detection

Quenching is a critical step during the strengthening age hardening of Aluminium alloys. To obtain optimal technological results, parts should be quenched with the upper critical cooling rate. The precipitation behaviour of Al alloys during cooling from solution annealing and thereby the critical cooling rates are typically investigated by in-situ measurements with differential scanning calorimetry (DSC). Conventional DSCs are limited at cooling rates below 10 Ks-1. Unfortunately, medium to high strength Al alloys typically have critical cooling rates between 10 and some 100 Ks-1. Recently it was shown that dilatometry is generally able for in-situ detection of precipitation in Al alloys. Dilatometry allows controlled cooling up to some 100 Ks-1 and therefore covers the cooling rate range relevant. In this work, we aim to show up and discuss possibilities and limitations of dilatometric detection of quench induced precipitates in 2xxx, and 7xxx Al alloys. The basic method will be presented and results will be compared with DSC work.

scholarly journals Development of Precipitation Hardening Parameters for High Strength Alloy AA 7068

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 918
Author(s):  
Julia Osten ◽  
Benjamin Milkereit ◽  
Michael Reich ◽  
Bin Yang ◽  
Armin Springer ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Maximum Yield ◽  
High Strength ◽  
Tensile Tests ◽  
Age Hardening ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
Critical Cooling Rate ◽  
Kinetics Of

The mechanical properties after age hardening heat treatment and the kinetics of related phase transformations of high strength AlZnMgCu alloy AA 7068 were investigated. The experimental work includes differential scanning calorimetry (DSC), differential fast scanning calorimetry (DFSC), sophisticated differential dilatometry (DIL), scanning electron microscopy (SEM), as well as hardness and tensile tests. For the kinetic analysis of quench induced precipitation by dilatometry new metrological methods and evaluation procedures were established. Using DSC, dissolution behaviour during heating to solution annealing temperature was investigated. These experiments allowed for identification of the appropriate temperature and duration for the solution heat treatment. Continuous cooling experiments in DSC, DFSC, and DIL determined the kinetics of quench induced precipitation. DSC and DIL revealed several overlapping precipitation reactions. The critical cooling rate for a complete supersaturation of the solid solution has been identified to be 600 to 800 K/s. At slightly subcritical cooling rates quench induced precipitation results in a direct hardening effect resulting in a technological critical cooling rate of about 100 K/s, i.e., the hardness after ageing reaches a saturation level for cooling rates faster than 100 K/s. Maximum yield strength of above 600 MPa and tensile strength of up to 650 MPa were attained.

The effect of cooling rate on crystallization behavior and tensile properties of CF/PEEK composites

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Cooling Rate ◽  
Crystallization Temperature ◽  
Crystallization Behavior ◽  
Crystalline Polymer ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Cooling Rates ◽  
Control Range ◽  
Temperature Range ◽  
Transverse Tensile

Abstract In this study, the differential scanning calorimetry (DSC) tests were performed to measure the nonisothermal crystallization behavior of carbon fiber reinforced polyether ether ketone (CF/PEEK) composites under different cooling rates. The characteristic parameters of crystallization were obtained, and the nonisothermal crystallization model was established. The crystallization temperature range of the material at different cooling rates was predicted by the model. The unidirectional laminates were fabricated at different cooling rates in the crystallization temperature range. The results showed that the crystallization temperature range shifted to a lower temperature with the increase of cooling rate, the established nonisothermal crystallization model was consistent with the DSC test results. It is feasible to shorten the cooling control range from the whole process to the crystallization range. The crystallinity and transverse tensile strength declined significantly with the increase of the cooling rate in the crystallization temperature range. The research results provided theoretical support for the selection of cooling conditions and temperature control range, which could be applied to the thermoforming process of semi-crystalline polymer matrixed composites to improve the manufacturing efficiency.

Mechanical Properties of Nanocrystalline Materials Produced by In Situ Consolidation Ball Milling

2008 ◽  
Vol 579 ◽  
pp. 15-28 ◽  
Author(s):  
Carl C. Koch ◽  
Khaled M. Youssef ◽  
Ron O. Scattergood
Keyword(s):  
Mechanical Properties ◽  
Ball Milling ◽  
Nanocrystalline Materials ◽  
Preparation Method ◽  
High Strength ◽  
Al Alloys ◽  
Ductile Metals ◽  
Cu Alloys ◽  
Bulk Nanocrystalline

This paper reviews a method, “in situ consolidation ball milling” that provides artifactfree bulk nanocrystalline samples for several ductile metals such as Zn, Al and Al alloys, and Cu and Cu alloys. The preparation method is described in this paper and examples of the mechanical behavior of nanocrystalline materials made by this technique are given. It is found that in such artifact-free metals, combinations of both high strength and good ductility are possible.

3D FEM Simulation of the Effect of Cooling Rate on SDAS and Macrosegregation of a High Strength Steel

2018 ◽  
Vol 941 ◽  
pp. 2360-2364 ◽  
Author(s):  
Gary Brionne ◽  
Abdelhalim Loucif ◽  
Chun Ping Zhang ◽  
Louis Philippe Lapierre-Boire ◽  
Mohammad Jahazi
Keyword(s):  
Boundary Conditions ◽  
Mushy Zone ◽  
Cooling Rate ◽  
High Strength Steel ◽  
Fem Simulation ◽  
High Strength ◽  
3D Fem ◽  
Cooling Rates ◽  
Positive Segregation ◽  
The Difference

Secondary dendrite arm spacing (SDAS) is a macrosegregation parameter directly linked to content of macrosegregation through cooling rates. The aim of this paper is to highlight the effect of cooling rate on the SDAS and macrosegregation patterns in a high strength steel. For this purpose, directionnal solidification in a cylinder was modeled with a plane-front solidification. Two cylinders were modeled with different boundary conditions (Tsurface = 1000°C and 1200°C). Using the FEM software Thercast, 3D macrosegregation maps were generated with thermomechanic algorithm taking into account metal shrinkage. Using Won’s equation, the influence of cooling rates in the mushy zone on SDAS was determined. The results indicated that a 72% lower difference in the area of negative macrosegregation zone (macrosegregation ratio (rseg) < -0.016%) for lower cooling rate (Ts = 1200°C). The difference of the area for positive segregation was 85% lower for higher cooling rates.

Rheological Behavior of Various Al Alloys during Solidification

2012 ◽  
Vol 710 ◽  
pp. 35-42
Author(s):  
Michel Suéry
Keyword(s):  
Ductile Fracture ◽  
Cooling Rate ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Liquid Films ◽  
Al Alloys ◽  
Tensile Behavior ◽  
Controlled Cooling ◽  
Sharp Transition ◽  
Solid Specimen

This paper is concerned with the tensile behavior of various Al alloys during solidification obtained by using an initially solid specimen heated locally until it becomes fully liquid and then partially solidified at a controlled cooling rate. It is shown that for Al-Cu as well as for Al-Si-Mg alloys, a similar behavior is observed with a sharp transition on the stress-solid fraction curve when the coalescence solid fraction of the dendrites is reached. Below the transition fracture occurs along liquid films for very low stresses whereas beyond this transition, ductile fracture is observed leading to higher stresses.

Controlled chiral arrangement of silver nanoparticles in supramolecular gels modulated by the cooling rate

2019 ◽  
Vol 55 (34) ◽  
pp. 4949-4952 ◽  
Author(s):  
Rong Wang ◽  
Jiaxi Cui ◽  
Xinhua Wan ◽  
Jie Zhang
Keyword(s):  
Silver Nanoparticles ◽  
Cooling Rate ◽  
Cooling Rates ◽  
Supramolecular Gels

Opposite helical arrangements of silver nanoparticles can be in situ achieved in organogels from a single gelator at different cooling rates.

Phase Transformation of M2 High Speed Steel during Semi-Solid Cooling and Conventional Cooling

2022 ◽  
Vol 327 ◽  
pp. 105-110
Author(s):  
Ting Sun ◽  
Yong Jin Wang ◽  
Ren Bo Song ◽  
Ya Zheng Liu ◽  
Jun Yanagimoto ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Microstructure Evolution ◽  
High Speed ◽  
High Speed Steel ◽  
Solid Particles ◽  
Controlled Cooling ◽  
Cooling Rates ◽  
M2 High Speed Steel ◽  
Conventional Cooling ◽  
Semi Solid

In this paper, the fundamental microstructure evolution of M2 high speed steel was investigated during semi-solid controlled cooling and conventional cooling, respectively. Semi-solid controlled cooling was conducted at 1260 °C with cooling rates from 0.1 to 10 °C/s, while conventional cooling was conducted at 1200 °C and 890 °C with different cooling rates. The continuous cooling transformation curves were plot according to the microstructure evolution. The results showed that microstructure transformation behavior of cooling structure in semi-solid temperature range was different from that of conventional process. For semi-solid specimen, the solid austenite dissolved more alloy elements, and the austenite stability was increased. The solid matrix was pearlite structure in the samples with cooling rate of 0.1 °C /s. When the cooling rate reached 1 °C/s, the granular pearlite disappeared and martensite lath was formed. The structure was relatively uniform, on which there were large carbide with regular shape. The solidified liquid phase showed a network shape surrounding the solid particles. The size of solid particles showed a decreasing trend with the increase of cooling rates. For conventional cooling process, the large eutectic M6C carbide and the small precipitated MC carbide could not be dissolved by austenitized at 890 °C. Increasing the austenitization temperature helped dissolving part of the carbides. The hardenability of M2 steel was high. The hardness has increased to a high level for both semi-solid and conventional specimens when cooling rate reached 1 °C/s. No obvious increase happened when cooling rate continued increasing.

Effect of Ultra-Fast Cooling Rate on the Microstructure and Mechanical Properties of High Strength Cold-Rolled Sheet under Continuous Annealing

2018 ◽  
Vol 913 ◽  
pp. 311-316
Author(s):  
Kai Zhang ◽  
Ren Bo Song ◽  
Feng Gao ◽  
Wen Jie Niu ◽  
Chi Chen
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Cooling Rate ◽  
High Strength ◽  
Rolled Sheet ◽  
Cooling Rates ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size ◽  
Cold Rolled ◽  
Fast Cooling

The effect of different fast cooling rates on the microstructure and mechanical properties of the V and Ti microalloyed high strength cold-rolled sheet was studied under laboratory conditions. Five different fast cooling rates were set up as 20°C/s, 50°C/s, 200°C/s, 500°C/s and 1000°C/s, respectively. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microstructure, and the mechanical properties were also tested. The results showed that with the increase of fast cooling rate from 20°C/s to 1000°C/s, the grains of martensite and ferrite were finer, and the average grain size of both martensite and ferrite decreased from 7.7μm to 3.9μm. The proportion of ferrite in the two phases decreased while that of the martensite increased from 25.7% to 62.1%. The morphology of martensite tended to be lath, and the density of dislocation in the ferrite grains nearby the martensite gradually increased. With cooling rate rising from 20°C/s to 1000°C/s, the yield strength of the experimental steel increased from 381MPa to 1074MPa, and the tensile strength increased from 887MPa to 1199MPa. And the elongation decreased from 14.2% to 7.2%, and the product of strength and elongation decreased from 12.6GPa·% to 8.6GPa·%.

Influence of Cooling Rates on Phase Transitions of Bent-Core Liquid Crystal 1,3-Phenylene-bis[4-(hexylcarboyloxyl)benzylideneamine]

2010 ◽  
Vol 428-429 ◽  
pp. 247-250 ◽  
Author(s):  
Yuan Ming Huang ◽  
Qing Lan Ma ◽  
Bao Gai Zhai
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transitions ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Cooling Rate ◽  
Scanning Calorimetry ◽  
Slow Cooling ◽  
Cooling Rates ◽  
Polarized Optical Microscopy ◽  
Fast Cooling

The influence of cooling rate on the phase transitions of a three-benzene-ring containing bent-core liquid crystal 1,3-phenylene-bis[4-(hexylcarboyloxyl)benzylideneamine] has been investigated by means of differential scanning calorimetry and polarized optical microscopy. Our results show that the cooling rates in the second cooling run pose significant effects on the phase transitions of the bent-core liquid crystal despite the cooling rates in the first cooling run pose little effects on the phase transitions. In the second cooling run, the banana phases survived only when the cooling rates were in the range of 14~15oC/min whereas both slow cooling rates which were less than 13oC/min and fast cooling rates which were higher than 16oC/min made the banana phases disappeared.

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