cause of magnesium castings to crack

Cause of Cracks in H-13 Aluminum Die Casting .

01-05-2013· Re: Cause of Cracks in H-13 Aluminum Die Casting Molds 04/26/2013 3:29 PM As is the case most of the time, we don't have any credible information here to work with.

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A Magnesium Crankcase Repair - Epoxyworks

The ignition cover of my off-road motorcycle is a magnesium casting. The casting is not heavily stressed but does have to hold the hot (about 140°F) oil that lubricates the engine. When I realized it cost $160 to replace the cover, I started thinking of the alternatives like, "how about using this epoxy we make for the repair and save some cash?"

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Solidification Shrinkage - an overview | .

Solidification-shrinkage and thermal-contraction imposed stresses/strains on weld HAZ are crucial in crack formation and propagation. According to Miller and Chadwick, 8 the critical tensile stress required to overcome surface tension, γ SL, on a grain boundary containing liquid film of thickness h, is given by:

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How to Avoid Cracking in Aluminum Alloys - ESAB

The aluminum/magnesium/silicon base alloys (6xxx series) are highly crack sensitive because the majority of these alloys contain approximately 1.0% Magnesium Silicide (Mg2Si), which falls close to the peak of the solidification crack sensitivity curve. The Mg2Si content of these materials is the primary reason there are no 6xxx series filler alloys.

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A Review of Common Metallurgical Defects in Ductile Cast Iron

magnesium range, 0.05% or above, will find that the iron is more prone to shrink than foundries operating at lower, but very acceptable, levels, say 0.035-0.04%. Both under-inoculation and over-inoculation can cause shrinkage. In the case of under-inoculation, not enough dissolved carbon is precipitated as graphite. Graphite nodules have a

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Die Casting: Possible Manufacturing Problems and .

When the mold temperature is too low, the shrinkage stress of the alloy increases, and the casting is prone to cracks. However, when the mold temperature is too high, it is advantageous to obtain a smooth surface of the casting, but it is prone to shrinkage depression.

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Casting Defects : Types, Causes and Remedies - .

These casting defects can be found out by the non destructive testing methods which includes ultrasonic testing, radiography testing, magnetic particle testing, die penetration testing etc. Today I will point out some common casting defects, its causes and remedies of it.

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Reduce Die Casting Cracks by Proper Use of .

NADCA EC-515 Die Casting Defects Course Review, Basics for controlling die casting defects - By Dr. Steve Midson. Reduce Die Casting Cracks, or tears, or hot cracks have many causes, but usually are at least partially caused by shrinkage cracks on the surface; Most often, the casting is stretched in the die as it cools because the die doesn't change dimensions while the casting is cooling ...

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What is Casting Defects - Types, Causes and .

11. Hot Tears or Hot Cracks. when the metal is hot it is weak and the residual stress (tensile) in the material cause the casting fails as the molten metal cools down. The failure of casting in this case is looks like cracks and called as hot tears or hot cracking.

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Fatigue Cracking Behaviors and Influence Factors .

01-11-2010· Figure 1. Typical microstructure of cast magnesium alloys. In addition, the shrinkage pores or other casting defects are also the microstructural feature of cast magnesium alloys as shown in Figs. 2.The shrinkage pores or casting defects are caused by the different deformation rates because there are different thermal expansions and elastic properties between the two phases.

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Failure investigations of helicopter tail rotor .

01-01-2016· Failure analysis of magnesium alloy castings can be very difficult due to their rapid oxidation, which can lead to even very recent cracks being heavily corroded. In addition, the absence of clear fracture features [ 7 ], such as fatigue striations, and the typical brittle fracture mode can make the analysis of failures by fatigue particularly problematic.

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The crack defect of magnesium die casting - .

The crack is irregular and filamentary crack on the smooth surface of the castings. It is deep in the casting, sometimes even penetrate the entire casting. There are two kinds of crack defect of magnesium die casting is more common, one is the crack is produced under the external force, the other is the shrinkage cracks when casting shrinkage.

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How to Avoid Cracking in Aluminum Alloys - AlcoTec

This alloy group welds easily with the high magnesium filler alloys such as 5356, which ensures the weld contains sufficient magnesium to prevent cracking. The recommendation of silicon-based filler alloys, such as 4043, for these alloys is not desirable because the excess Si introduced by the filler alloy can result in the formation of excessive amounts of brittle Mg 2 Si particles in the weld.

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Welding Forum > Magnesium casing repair

09-05-2010· The last magnesium engine cases were used in about 1982 in European built VW's, and the gearboxes remained magnesium until the rear engined buses ended production in 1990 (2WD) / 1992 (4WD). New magnesium type 1 engine cases are still made in Brazil / Mexico, for service replavement / aftermarket, as the air cooled engines went out of production a couple of years ago.

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Can one fix cracked magnesium?, page 1

Last week i was cleaning up my garage when i bumped on a magnesium engine head cover i had replaced last year. The damn thing was pretty expensive to get replaced. I gazed at it just to remember there were no signs of a fall what so ever! It looks brand new except for that hairline crack that can be seen from the inside.

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casting foundry defects the cause and resolve .

And cracks are easily caused when the mold cavity itself has cracks. Control methods: 1. should pay attention to the foundry casting structure of the process, need to do the uniform transition of the uneven thickness of the casting parts, using the appropriate size of the fillet. 2.

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A Magnesium Crankcase Repair - Epoxyworks

The ignition cover of my off-road motorcycle is a magnesium casting. The casting is not heavily stressed but does have to hold the hot (about 140°F) oil that lubricates the engine. When I realized it cost $160 to replace the cover, I started thinking of the alternatives like, "how about using this epoxy we make for the repair and save some cash?"

Get Price


Influence of porosity on the fatigue limit of die cast ...

of approx. 38–50 MPa (magnesium alloys) and 75 MPa (AlSi9Cu3) in the tested casting condition. Fatigue cracks initiated at porosity in 98.5% of the samples. Considering porosity as initial cracks, specimens fail, if critical stress intensity amplitude, Kcr is exceeded.

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Armoloy Treatment of Die Castings to Retard Heat .

T The life of aluminum and magnesium die castings dies can be extended considerably with the Armoloy Process. This already has been proven using the Armoloy coating on dies, especially those affected by heat checking. When the Armoloy treatment is applied early in the life of the die, the number of castings made from the die can be increased and more profits generated.

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How to Tig Weld Magnesium – Welding Mastermind

When repairing magnesium, it is important to note that while other methods are available that tig welding is the most common way to repair magnesium castings. This is because tig welding was invented to weld on magnesium and aluminum by Northrop Aircraft Corporation in the 1940's.

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Magnesium die casting: frequently asked questions

Galvanic corrosion occurs when there is a dissimilar metal in contact with the magnesium casting and there is an electrolyte present (such as salt water). There is no issue with interior components but for body, chassis or power-train castings there is a likelihood that .

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Magnesium repair... crack

27-05-2004· I've got an older motorcycle with a crack on the crank case cover. I've never welded on Magnesium before, but I have welded on Aluminum. I've heard that the two have similar welding characteristics. I have access to all types of welding processes, but .

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Welding Forum > Magnesium casing repair

09-05-2010· The last magnesium engine cases were used in about 1982 in European built VW's, and the gearboxes remained magnesium until the rear engined buses ended production in 1990 (2WD) / 1992 (4WD). New magnesium type 1 engine cases are still made in Brazil / Mexico, for service replavement / aftermarket, as the air cooled engines went out of production a couple of years ago.

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Hot Cracks vs. Stress Cracks in Aluminum Welding .

28-11-2018· For silicon, magnesium and magnesium silicide crack sensitivity peaks at around 1% and then declines. When copper is the alloying element sensitivity peaks at about 3%. Armed with this knowledge, a strategy for welding aluminum starts to emerge. First, look at the composition.

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How to Prevent Corrosion of Magnesium Alloy .

Manufacturers of magnesium alloy die-casting remind that the oxide film on the surface of magnesium alloy has a protective effect in a long time under the dry oxygen of 450 ℃. 4.Corrosion fatigue Under fatigue loading, the origin of microcracks in magnesium .

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Several main factors affecting the quality of .

The alloying elements commonly used in Magnesium Die Casting Parts fluids are aluminum and zinc. In order to ensure the casting performance, the aluminum content of the die-cast magnesium alloy is >3%, and the zinc content is <2%. Otherwise, short cracks will occur.

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TROUBLESHOOTING CRACKS IN STEEL CASTINGS

Hot-Crack Cures 1. Follow casting design rules: • Larger radii, tapered junction between sections 2. Provide localized cooling: • Cracking brackets (cooling fins) across crack • Chilling sand or chilling coating in radii (chromite, zircon) 3. Provide mold support to heavy/hot section (very large castings .

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Finishing of Magnesium

Process - Pickling of magnesium alloy castings. Used for surface inspection (Type I) or to remove casting skin contamination (Type II) sulfuric acid solution. Makeup - 3 - 7 fl.oz./gal Temperature 70 - 90 ° F Tank corrosion resistant plastic hydrofluoric acid solution. Makeup - hydrofluoric acid 1 part Water - 4 parts Temperature 70-90F

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Crack Propagation Analysis of Magnesium Rod Processed by ...

of ~50 μm after casting but this was reduced to ~12 μm ... Crack Propagation Analysis of Magnesium Rod Processed by Extrusion-shear: Numerical Modeling and Experimental Verification ... die angle 180 °could cause continuous cracks on the surface of the extruded rod.

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The crack defect of magnesium die casting - .

The crack is irregular and filamentary crack on the smooth surface of the castings. It is deep in the casting, sometimes even penetrate the entire casting. There are two kinds of crack defect of magnesium die casting is more common, one is the crack is produced under the external force, the other is the shrinkage cracks when casting shrinkage.

Get Price