Segregation Characteristics of Rheo-High Pressure Die Cast Al-Alloy 2139 Plates

2015 ◽  
Vol 828-829 ◽  
pp. 100-105 ◽  
Author(s):  
Carlien Taute ◽  
Heinrich Möller
Keyword(s):  
High Pressure ◽  
Die Casting ◽  
Hot Tearing ◽  
Three Dimensions ◽  
Age Hardening ◽  
Al Alloy ◽  
Die Cast ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Pressure Die Casting

Al-Cu-Mg-Ag alloy 2139 is a wrought alloy that is heat-treatable and used in aerospace constructions. This is mainly due to the addition of silver in the alloy. Hot-tearing is a problem for casting wrought alloys with conventional liquid casting techniques. The risk is reduced by using rheo-high pressure die casting (R-HPDC) to allow the alloy to be used for near-net shape forming of components. This study investigates the segregation characteristics of R-HPDC alloy 2139. The effects of segregation on the age-hardening response as well as the tensile properties are studied. The chemical composition differences across the casting were found to aid in correlation of results. It is found that segregation occurs in three dimensions, namely from the surface to the centre of the casting, as well as across the width and length of the casting.

Fusion Welding of Rheocast Semi-Solid Metal (SSM) Processed Aluminium Alloy 7017

2012 ◽  
Vol 192-193 ◽  
pp. 161-166 ◽  
Author(s):  
Madeleine du Toit ◽  
Patronica Letsoalo ◽  
Heinrich Möller
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Aluminium Alloy ◽  
Die Casting ◽  
Solid Metal ◽  
Hot Tearing ◽  
High Pressure Die Casting ◽  
Near Net Shape ◽  
Semi Solid ◽  
Pressure Die Casting

Near-net shape casting of wrought aluminium alloys has proven to be difficult due to a tendency towards hot tearing during cooling. Rheocasting, or semi-solid metal (SSM) processing followed by high pressure die casting (HPDC), has recently been shown to be an effective alternative to conventional die casting, yielding near-net shape wrought aluminium alloy castings with less risk of hot tearing. This casting process involves pouring the liquid metal into a processing cup, which is then transferred into a coil for induction stirring and simultaneous forced air cooling. When the metal reaches the semi-solid casting temperature, the resultant slurry is transferred to a high pressure die casting machine and cast to near-net shape. This modifies the as-cast microstructure, yielding a more globular primary phase and results in mechanical properties in the -T6 condition closely approaching those of wrought material in the same condition. Little information is currently available on the response of SSM-HPDC material to welding. This project investigated the influence of autogenous laser and gas tungsten arc welding on the microstructure and mechanical properties of aluminium 7017 after rheocasting. It is possible to successfully weld this material without solidification or liquation cracking. The effect of welding on the rheocast microstructure in the heat-affected zone and weld metal was shown, and the hardness and tensile properties of the resulting joints in the as-welded condition were tested and related to the microstructures achieved.

Failure analysis of H13 steel die for high pressure die casting Al alloy

2021 ◽  
pp. 105330
Author(s):  
Rengen Ding ◽  
Haibo Yang ◽  
Shuzhi Li ◽  
Guodong Wu ◽  
Jiahao Mo ◽  
...  
Keyword(s):  
High Pressure ◽  
Failure Analysis ◽  
Die Casting ◽  
Al Alloy ◽  
H13 Steel ◽  
High Pressure Die Casting ◽  
Pressure Die Casting

Al-Mg-Si-(Cu) 6xxx Series Alloy Selection for Rheo-High Pressure Die Casting

2014 ◽  
Vol 1019 ◽  
pp. 61-66
Author(s):  
Heinrich Möller ◽  
Pfarelo Daswa ◽  
Gonasagren Govender
Keyword(s):  
High Pressure ◽  
Selection Process ◽  
Die Casting ◽  
Solution Treatment ◽  
Hot Tearing ◽  
Incipient Melting ◽  
Negative Effects ◽  
High Pressure Die Casting ◽  
Pressure Die Casting ◽  
6Xxx Series

<span><span style="font-family: Times New Roman;" face="Times New Roman"><span style="font-family: Times New Roman;" face="Times New Roman"></span></span> <p><span style="font-family: Times New Roman;" face="Times New Roman">This paper investigates the selection process of Al-Mg-Si-(Cu) 6xxx series alloys when used specifically for rheo-high pressure die casting (R-HPDC). The 6xxx series alloys have been developed as wrought alloys and certain factors must be taken into consideration when utilising them for semi-solid metal processing. It is shown that chemical composition has a significant effect on the solution treatment parameters that should be employed i.e. high Cu and excess Si levels necessitate the use of a two-step solution treatment to reduce incipient melting. This incipient melting is especially severe in areas within the component where liquid segregation occurs, which is a common phenomenon in R-HPDC. However, high Cu and excess Si levels also have advantages: it results in higher T6 strength and Cu-additions have been shown to minimise the negative effects of natural pre-ageing. Therefore, the composition of the alloy must be selected in such a way as to achieve acceptable strength without the dangers of incipient melting in liquid segregated areas. Another important modification of 6xxx series alloys used for R-HPDC that is presented is the addition of Ti to minimise hot tearing. </span></p> <p align="LEFT"><span style="font-family: Times New Roman; font-size: medium;" face="Times New Roman" size="3"> </span></p>

Rheocasting an Engine Mounting Bracket in Commercial 7075

2011 ◽  
Vol 690 ◽  
pp. 133-136 ◽  
Author(s):  
Ulyate Andries Curle
Keyword(s):  
High Pressure ◽  
Die Casting ◽  
Hot Tearing ◽  
Injection Velocity ◽  
The Novel ◽  
X Ray ◽  
High Pressure Die Casting ◽  
Casting Technique ◽  
Casting Section ◽  
Pressure Die Casting

Wrought aluminium alloys are prone to hot tearing when cast into near-net shapes. This problem can be overcome by the novel casting technique of rheo-processing combined with high pressure die casting. An industrial engine mounting bracket is produced by rheo-process commercial 7075 with the patented CSIR-RCS and subsequent high pressure die casting. Section thickness changes and constraining geometry make this a difficult component to rheocast. X-ray radiography is used to evaluate hot tearing over the component and is correlated to piston injection shot profile velocities. Gross hot tearing is significantly reduced by a higher injection velocity but turbulent flow entraps air. Faster injection allows more time for flow before final solidification.

scholarly journals Age-hardening of high pressure die casting AlMg alloys with Zn and combined Zn and Cu additions

2019 ◽  
Vol 181 ◽  
pp. 107927 ◽  
Author(s):  
Lukas Stemper ◽  
Bernhard Mitas ◽  
Thomas Kremmer ◽  
Steffen Otterbach ◽  
Peter J. Uggowitzer ◽  
...  
Keyword(s):  
High Pressure ◽  
Die Casting ◽  
Age Hardening ◽  
High Pressure Die Casting ◽  
Pressure Die Casting

Microstructure and Mechanical Properties of Low Pressure Die Cast AM50 Magnesium Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 167-170 ◽  
Author(s):  
Li Ming Peng ◽  
Peng Huai Fu ◽  
Hai Yan Jiang ◽  
Chun Quan Zhai
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Die Casting ◽  
Low Pressure ◽  
Microstructure And Mechanical Properties ◽  
Heat Treated ◽  
Die Cast ◽  
Second Phases ◽  
Am50 Alloy ◽  
Pressure Die Casting

Compact AM50 alloy components were cast by Low Pressure Die Casting (LPDC) process. The microstructure and mechanical properties of cast components were investigated under as-cast and heat treated states. It was found that the microstructure of LPDC AM50 is composed of α-Mg and second phases - Mg17Al12 and Al8Mn5. Compared with Gravity die casting, LPDC AM50 alloy had much coarser grains and higher density, with smaller sizes and less content of second phases. The density of AM50 alloy by LPDC process was ρ=1.7836g/cm3, with increase of 0.45% based on Gravity die casting and much more increase compared with high pressure die casting. The as-cast mechanical properties by LPDC process were: σ0.2=57.8Mpa, σb=192.3Mpa, δ=8.7%. These of Gravity die casting were: σ0.2=53Mpa, σb=173.4Mpa, δ=8.1%. UTS in LPDC increased about 20MPa, with better YTS and Elongation. Compared with that of high pressure die cast AM50, the YTS of LPDC was much lower, with comparable UTS and Elongation. The mechanical properties of the heat treated AM50 alloy were still in the same level of as-cast state. AM50 alloy by LPDC process is not necessary subjected to tempering treatment.

Age-Hardening of Rheo-High Pressure Die Cast Al-Alloy 6066

2014 ◽  
Vol 1019 ◽  
pp. 47-54
Author(s):  
Carlien Taute ◽  
Heinrich Möller
Keyword(s):  
High Pressure ◽  
High Performance ◽  
Solution Treatment ◽  
Heat Treatments ◽  
Hot Tearing ◽  
Age Hardening ◽  
Al Alloy ◽  
Artificial Ageing ◽  
One Step ◽  
Semi Solid

Al-Mg-Si-Cu alloy 6066 is a heat-treatable wrought alloy that is commonly used in high performance bicycle frames. Wrought alloys are difficult to cast using conventional liquid casting techniques, as hot tearing can occur. However, a method that effectively reduces that risk is rheo-high pressure die casting (R-HPDC). Casting alloy 6066 using semi-solid metal processing makes it possible to be used for near-net shape forming of components. This study investigates the age-hardening response of R-HPDC alloy 6066. The effects of different solution heat treatments, natural pre-ageing and artificial ageing are studied. The different solution heat treatments investigated are a one-step and a two-step solution treatment. The one-step treatment was performed at 530°C only and the two-step treatment at 530°C followed by 550°C. It is shown that natural pre-ageing has a detrimental effect on the T6 properties and that the longer two-step solution heat treatment is justified due to an increase in hardness and prevention of incipient melting. The Vickers hardness in different temper conditions (F, T4, T5 and T6) were determined and compared to the typical hardness values of the alloy in the wrought condition.

scholarly journals Assessment of Mechanisms for Particle Migration in Semi-Solid High Pressure Die Cast Aluminium-Silicon Alloys

2020 ◽  
Vol 4 (2) ◽  
pp. 51
Author(s):  
Madeleine Law ◽  
Christopher Neil Hulme-Smith ◽  
Taishi Matsushita ◽  
Pär G. Jönsson
Keyword(s):  
High Pressure ◽  
Die Casting ◽  
Particle Migration ◽  
Silicon Alloys ◽  
High Pressure Die Casting ◽  
Die Cast ◽  
Semi Solid ◽  
Pressure Die Casting ◽  
Saffman Lift Force ◽  
Externally Solidified Crystals

In semi-solid metal high pressure die casting and in conventional high pressure die casting, it is common to find a defect band just below the surface of the component. The formation of these bands is not fully understood. However, there are several theories as how they occur, and it has been suggested that segregation is caused by the migration of aluminium-rich externally solidified crystals. In the present work the formation of these bands is investigated theoretically by reviewing suitable potential mechanisms for the migration of such crystals. Two mechanisms are identified as the most probable: Saffman lift force and the Mukai-Lin-Laplace effect. However, it was not possible to identify which of these two mechanisms acted in the case studies. Further testing is required to identify the mechanism that is causing the migration of the aluminium globules and suitable tests are proposed.

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