Structural Stability of Welded Joints of Magnesium Alloy EZ33A-T5

2014 ◽  
Vol 782 ◽  
pp. 408-414
Author(s):  
Robert Kocurek ◽  
Janusz Adamiec
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Welded Joints ◽  
Welded Joint ◽  
Research Work ◽  
Structure And Properties ◽  
Alloy Casting ◽  
Shrinkage Cracks ◽  
Lack Of Information ◽  
Alloy Castings

Magnesium alloys of Mg-Zn-RE-Zr group are characterized by creep resistance up to 250°C, good castability, absence of the microporosity and gas corrosion resistance. Defect of these alloys are low mechanical properties at ambient temperature. Magnesium alloys are used in the automotive, aerospace and defense industries, mainly as gravitational casts to sand moulds or die-casting. Casting defects often appear in these casts (misruns, micro-shrinkage, cracks), especially for large-size castings. The welding technologies are most often applicable to repair of casts, mainly non-consumable electrode welding in the inert-gas cover. Welded joints made of magnesium alloys should have properties at least the same as the ready cast, in particular it should ensure stability of the structure and properties of all welded joint in working temperature. In the literature there is a lack of information about stability and properties of welded joints of Mg-4E-3Zn (EZ33A-T5 acc. to ASTM B80) alloy castings. In research work determined the structure of welded joints of Mg-4RE-3Zn alloy casting after stress-relief annealing and defined changes of structure and properties during long-term annealing at the temperature of 250°C. It was found that the structure of welded joint of casting alloy Mg-4RE-3Zn is stable at the temperature of 250°C through at least 1000 hours. The hardness of tested joints equal 80 HV. Therefore welding technologies can be used for repair of magnesium alloy casts with addition of zinc and rare earth elements.

The Repair Welding Technology of Casts Magnesium Alloy QE22

2013 ◽  
Vol 212 ◽  
pp. 81-86 ◽  
Author(s):  
Robert Kocurek ◽  
Janusz Adamiec
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Research Work ◽  
Inert Gas ◽  
Repair Welding ◽  
Welding Technology ◽  
Alloy Castings ◽  
Stable Connection

Alloys from group Mg-Ag-RE-Zr are characterized by creep resistance up to 200°C, good casting and mechanical properties. Defects of magnesium alloys are propensity to cracks and deformations during heat treatment, low corrosion resistance. Welding technologies are most often use to repair of casts, mainly nonconsumable electrode welding in inert gas cover. About possibility repair or regeneration of magnesium alloy castings by welding depends on their weldability. Weldability of most magnesium alloys is good however, welding and surfacing cast elements create many problems. The purpose of this research work was develop a repair welding technology of casts magnesium alloy. Research project consisted of weldings and padding trials, microstructure and mechanical properties tests. Presented research results in this paper support conclusion that casts alloy QE22 reveal susceptibility to stable connection.

scholarly journals The Effect of LFC Process Variables on Solidification and Thermal Response of AZ91E Magnesium Alloy Castings

2021 ◽  
Author(s):  
Lukas Bichler
Keyword(s):  
Thermal Analysis ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Metal Flow ◽  
Mold Filling ◽  
Second Phase ◽  
Process Variables ◽  
Pyrolysis Products ◽  
Alloy Castings ◽  
Non Equilibrium

Magnesium alloys are gaining in popularity as materials of choice for automotive and aerospace applications. Magnesium alloys have the lowest density of all structural metals, effectively making their specific properties highly attractive. Lost Foam Casting (LFC) is a novel near-net-shape manufacturing process utilizing expanded polystyrene (EPS) as a mold filler. Presence of the EPS in the casting cavity promotes formation of unique casting defects.These include misruns, folds, entrapped polystyrene pyrolysis products and potentially increased levels of gas porosity. There is very little published literature on the feasibility of casting magnesium alloys by the LFC process. This research was an attempt to evaluate the effect of selected LFC process variables on AZ91R magnesium alloy castings produced by the LFC process. In this work, the effect of melt superheat, casting section thickness, EPS foam properties and the application of vacuum during mold filling were investigated and correlated to the casting quality and molten flow behavior. Further, detailed thermal analysis was carried out to determine the solidification history of the castings. The results of the thermal analysis were used to determine the effect of the cooling rate on the development of the casting microstructure. Moreover, the morphology and the mode of second phase (Mg17Al12) precipitation were studied and quantified. The results suggest that application of vacuum during the mold filling process increased the metal flow lengths. However, the casting soundness deteriorated due to the applied vacuum. Variations in the density of the vacuum cast horizontal bars were explained through the presence of partially solidified metal. The molten metal flow was further influenced by the foam density and bead fusion. Greater flow lengths were observed in the high density 1.6 pcf foam castings. in the low density 1.3 pcf foam castings, numerous casting defects were associated with the presence of the liquid-EPS pyrolysis products. In general, the thermal analysis suggested that non-equilibrium alloy solidification promoted the formation of the lamellar non-equilibrium Mg17Al12 precipitate, and this was confirmed by optical microscopy.

Review of Status about the Effect of Ultrasonic Impact on Fatigue Properties of Welded Joints of Magnesium Alloy

2013 ◽  
Vol 668 ◽  
pp. 835-839 ◽  
Author(s):  
Ying Xia Yu ◽  
Bo Lin He ◽  
Bin Wang ◽  
Shang Yu Zhou
Keyword(s):  
Residual Stress ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Welded Joints ◽  
Welded Joint ◽  
Development Trend ◽  
Fatigue Properties ◽  
Concentration Coefficient ◽  
The Development Trend ◽  
Stress Concentration Coefficient

The study on magnesium alloy has attracted attention at home and abroad. Status and development trend about the fatigue properties of welded joints of magnesium alloy were reviewed. The main problems and deficiencies were pointed out, and the recent development's focus was outlined. The development trend of improving the fatigue propeties and fatigue life was analyzed. The ultrasonic impact method can not only decrease the stress concentration coefficient and tensile residual stress of welded joint, but also refine the grain size of welded joints, even to compressive stress and nanograins. The method has put forward a new way for increasing fatigue properties and life of welded joint of magnesium alloy.

The Influence of Pulsed Heat and Power Supply on the Structure and Properties of Welded Joint Metals and Surfaced Coatings

2015 ◽  
Vol 788 ◽  
pp. 259-266
Author(s):  
Yuriy N. Saraev ◽  
Valeriy P. Bezborodov ◽  
Evgenya A. Putilova
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Weld Metal ◽  
Power Supply ◽  
Welded Joints ◽  
Arc Welding ◽  
Structural Changes ◽  
Welded Joint ◽  
Structure And Properties ◽  
Pulsed Mode

We have investigated the influence of the modes of adaptive pulse-arc welding and surfacing on the structure and physical-mechanical properties of welded joints of steel 09Mn2Si and the surfaced composition of this steel coated with a modified powder material of chromium carbide with the submicrocrystalline structure. It is shown that the pulsed mode of welding and surfacing can improve the homogeneity of the structure of the welded joint of steel and a surfaced coating and reduce the grain size of metals in both of them. Structural changes lead to an increase in ductility and toughness of the weld metal.

The Quantitative Assessment of the Fracture Profile of Magnesium Alloy QE22 Welded Joint

2013 ◽  
Vol 197 ◽  
pp. 215-220
Author(s):  
Janusz Adamiec
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Creep Test ◽  
Welded Joints ◽  
Short Exposure ◽  
Fracture Profile ◽  
Heat Treated ◽  
Basic Source ◽  
Lightweight Alloys ◽  
Source Of Information

Magnesium alloys are a part of a group of lightweight and ultra-lightweight alloys, which are important in practical use in constructions. QE22 casting magnesium alloy containing silver, rare earth elements and zirconium is characterized by creep resistance up to the temperature of 200 °C, while during a short exposure it can resist up to the temperature of 250°C. Nowadays, QE22 magnesium alloy are used for casting into sand moulds. In castings of magnesium alloys defects or inconsistencies (such as casting misruns, porosities and cracks) often appear, particularly in huge dimensional castings. Such defects are repaired with the use of padding and welding. Welded joints must ensure suitable operational properties, mainly in terms of creep, so that the repaired casting can work under the same conditions as the correct cast. The basic source of information about the cause and cracking propagation is fracture after creep test. The quantitative fractography, in particular profilomety, allows to describe the fracture and basis on it conclude the causes of destruction. In this paper quantitative procedure for assessing the fracture profile of QE22 welded joints after creep test was worked out. Base on its analysis result, it was found that creep resistant of the QE22 joints is determined by eutectic areas, therefore they must be heat treated after welding joints.

Impact of Heat Treatment on the Structure and Properties of the QE22 Alloy Welded Joints

2012 ◽  
Vol 191 ◽  
pp. 183-188
Author(s):  
Agata Kierzek ◽  
Janusz Adamiec
Keyword(s):  
Heat Treatment ◽  
Welded Joints ◽  
Creep Resistance ◽  
Welded Joint ◽  
Casting Process ◽  
Structure And Properties ◽  
Cast Magnesium Alloy ◽  
The One ◽  
Cast Magnesium ◽  
The Impact

The QE22 cast magnesium alloy containing silver, rare earth elements and zirconium is characterized by high mechanical properties and creep resistance of up to 200 ° C. It is cast gravitationally into sand moulds and permanent moulds. After the casting process any possible defects appearing in the cast are repaired with the application of welding techniques. The repaired cast should possess at least the same properties as the one which does not require any repairs. The aim of this thesis was to determine the impact of the heat treatment on the microstructure of the QE22 alloy welded joint. The creep resistance of the welded joints was also analyzed.

Formation of Fold Defects in Permanent Mold Cast AE42 Magnesium Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 1591-1595
Author(s):  
Lukas Bichler ◽  
Comondore Ravindran
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Microstructural Analysis ◽  
Surface Flow ◽  
Rapidly Solidify ◽  
Permanent Mold ◽  
Process Formation ◽  
Mold Casting ◽  
Macro Scale ◽  
Alloy Castings

Application of magnesium alloys potentially plays a key role in weight reduction of automotive and aerospace components. Majority of magnesium components are manufactured via the high-pressure die-casting (HPDC) or permanent-mold casting (PMC) processes. In general, castability of magnesium alloys is comparable to aluminum alloys. However, unique defects related to the high susceptibility of magnesium to rapidly solidify, dissolve hydrogen or form oxides potentially contribute to material failure. In this research, AE42 magnesium alloy castings were manufactured via the PMC process. Formation of fold defects in regions of high melt turbulence was observed on the macro-scale as visible surface flow-lines. Microstructural analysis revealed that folds in the AE42 alloy we related to the rapid solidification and short alloy freezing range. Further, segregation of Al2RE intermetallics at the metal front hindered proper fusion of merging metal fronts.

scholarly journals The Effect of LFC Process Variables on Solidification and Thermal Response of AZ91E Magnesium Alloy Castings

2021 ◽  
Author(s):  
Lukas Bichler
Keyword(s):  
Thermal Analysis ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Metal Flow ◽  
Mold Filling ◽  
Second Phase ◽  
Process Variables ◽  
Pyrolysis Products ◽  
Alloy Castings ◽  
Non Equilibrium

Magnesium alloys are gaining in popularity as materials of choice for automotive and aerospace applications. Magnesium alloys have the lowest density of all structural metals, effectively making their specific properties highly attractive. Lost Foam Casting (LFC) is a novel near-net-shape manufacturing process utilizing expanded polystyrene (EPS) as a mold filler. Presence of the EPS in the casting cavity promotes formation of unique casting defects.These include misruns, folds, entrapped polystyrene pyrolysis products and potentially increased levels of gas porosity. There is very little published literature on the feasibility of casting magnesium alloys by the LFC process. This research was an attempt to evaluate the effect of selected LFC process variables on AZ91R magnesium alloy castings produced by the LFC process. In this work, the effect of melt superheat, casting section thickness, EPS foam properties and the application of vacuum during mold filling were investigated and correlated to the casting quality and molten flow behavior. Further, detailed thermal analysis was carried out to determine the solidification history of the castings. The results of the thermal analysis were used to determine the effect of the cooling rate on the development of the casting microstructure. Moreover, the morphology and the mode of second phase (Mg17Al12) precipitation were studied and quantified. The results suggest that application of vacuum during the mold filling process increased the metal flow lengths. However, the casting soundness deteriorated due to the applied vacuum. Variations in the density of the vacuum cast horizontal bars were explained through the presence of partially solidified metal. The molten metal flow was further influenced by the foam density and bead fusion. Greater flow lengths were observed in the high density 1.6 pcf foam castings. in the low density 1.3 pcf foam castings, numerous casting defects were associated with the presence of the liquid-EPS pyrolysis products. In general, the thermal analysis suggested that non-equilibrium alloy solidification promoted the formation of the lamellar non-equilibrium Mg17Al12 precipitate, and this was confirmed by optical microscopy.

Influence of Cooling Rate on Fatigue Behaviour of Eutectic Al-Si (A413) Alloy Casting

2015 ◽  
Vol 787 ◽  
pp. 490-494
Author(s):  
M. Mohandass ◽  
Jamuna Venkatesan ◽  
N. Nallusamy
Keyword(s):  
Cooling Rate ◽  
Room Temperature ◽  
Stress Ratio ◽  
Cast Alloy ◽  
Research Work ◽  
Fatigue Behaviour ◽  
Structural Morphology ◽  
Alloy Casting ◽  
Sinusoidal Waveform ◽  
Alloy Castings

In this research work, the effect of cooling rate on fatigue behaviour of eutectic A413 Al-Si cast alloy is investigated. Castings produced by two different cooling rates, water-cooled and air-cooled are studied. The structural morphology of alloy castings was characterized using Inverted Trinocular Metallurgical Optical Microscopy. A Comprehensive tension–tension fatigue test was carried out with a stress ratio of R=0.5, and a sinusoidal waveform under three different mean stress conditions (25%, 50% & 75% of UTS) at room temperature (32°C). The microstructural evaluations show that the eutectic script size is smaller for water-cooled casting than the air-cooled casting. It is also observed that the fatigue life of the water-cooled cast alloy is greater than that of cast alloy produced with conventional air-cooled method.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

Sign in / Sign up

Export Citation Format

Share Document