Wrought Magnesium Alloy Sheets Research Articles

Estimation of Cold Roll Forming Characteristics of Wrought Magnesium Alloy with Tension-Compression Asymmetry

In recent years, the movement for banning the sale of gasoline cars and diesel vehicles, especially in Europe, and allowing only electric passenger cars has been accelerated. For examples, Germany’s federal council, the Bundesrat, has passed a resolution calling for a ban on combustion engine cars by 2030. If the ban were to go through, German citizens would only be permitted to purchase electric or hydrogen-fueled cars. In Norway, until 2025 there is a movement for legislation prohibiting the registration of new gasoline passenger cars and diesel cars. Beginning in 2025 in the Netherlands, a bill prohibiting the sale of new cars gasoline and diesel vehicles was submitted to Congress. Under the circumstances, the demand for light-weight products for automotive industries has increased due to global trends in environmental preservation. Although demands for magnesium has risen dramatically, production of magnesium alloy sheet still remains at a very low level. This study seeks to establish a guideline for roll design in the roll forming of wrought magnesium alloys to extend practical use of roll-formed products of wrought magnesium alloys. A three-dimensional elasto-plastic analysis by the finite-element method has been conducted to express exact roll-forming behavior of wrought magnesium alloys that have different stress-strain curves in tension and compression. Simple V-sections were formed by a tandem six-stand roll forming machine to demonstrate the effectiveness of the simulation methods with different stress-strain curves in the case of tension and compression. Also, spring-back analysis has been performed to investigate the exact cold roll-forming phenomenon for wrought magnesium alloy sheets.

Effects of single-pass large-strain rolling on microstructure and mechanical properties of Mg-Al-Ca alloy sheet

A new wrought magnesium alloy sheet, the Mg-1.8Al-1.8Ca wt.% alloy, with high strength and good ductility has been fabricated by the one-step extrusion and subsequent single-pass large-strain rolling process. The microstructure analysis shows that a large amount of un-dynamically recrystallized (un-DRXed) regions exist in the as-extruded alloy. After the large-strain rolling process, the grain size of the sheet is refined and the microstructure becomes more uniform, as compared with the as-extruded counterpart. The average grain size of Mg-1.8Al-1.8Ca alloy is refined from the ~ 2.42 μm in the as-extruded state, to be ~ 1.68 μm and ~ 1.42 μm, after rolling at 350 °C and 300 °C, respectively. The wrought Mg-1.8Al-1.8Ca alloy sheet, which was rolled at 300 °C by one-pass thickness reduction of ~ 78%, exhibits the highest absolute strengths with yield strength of ~ 298 MPa and ultimate tensile strength of ~ 319 MPa, and the moderate elongation to failure of ~ 6% is also obtained.

Cold Roll Forming Behavior of Wrought Magnesium Alloy with Tension - Compression Asymmetry

In recent years, the movement that banning the sale of gasoline cars and diesel vehiclesespecially in Europe and allowing only electric cars for passenger’s cars has been accelerated. Forexamples, Germany’s federal council, the Bundesrat, has passed a resolution calling for a ban oncombustion engine cars by 2030. If the ban were to go through, German citizens would only bepermitted to purchase electric or hydrogen-fueled cars. In Norway, until 2025 there is a movement tolegislation prohibiting the registration of new cars for passenger car gasoline and diesel cars.Beginning in 2025 in the Netherlands, a bill to prohibit the sale of new cars for gasoline and dieselvehicles was submitted to Congress. Under the circumstances, the growing demand for light weightproducts for automotive industries has been increased due to global trend of environmentalpreservation. Although requires of magnesium has risen dramatically, production of magnesium alloysheet remains still at a very low level in practical use. The aim of the study is to establish a guidelinefor roll design in the roll forming of wrought magnesium alloys to extend practical use of roll formedproducts of wrought magnesium alloys. A three-dimensional elasto-plastic analysis by finite elementmethod has been conducted to express exact roll forming behavior of wrought magnesium alloys thathave different stress-strain curves in tension and compression. A simple V-sections were formed by atandem six stands roll forming machine to demonstrate effectiveness of the simulation methods withdifferent stress-strain curves in the case of tension and compression. Also, spring back analysis hasbeen performed to investigate exact cold roll forming phenomenon for wrought magnesium alloysheets.

Improving the room-temperature formability of Mg-3Al-1Zn alloy sheet by introducing an orthogonal four-peak texture

Wrought magnesium alloy sheets suffered extrusion or rolling usually exhibit strong basal texture, which greatly degrades their mechanical performance, and thus, restrict their applications. In this study, a novel texture modification process based on employing in-plane precompression, prestretching and annealing was carried out on an extruded Mg-3Al-1Zn (AZ31) sheet to introduce an orthogonal four-peak distribution of basal texture. The results indicated that such an orthogonal four-peak texture could provide larger and more balanced Schmid factors for basal slip compared with that of the as-extruded sheet when the sheets subject to tension along different directions. As expected, the tensile yield strength was decreased and the ductility was increased effectively, suggesting a considerable improvement in uniaxial deformation ability. Additionally, the orthogonal four-peak texture could also provide more balanced mechanical properties along different directions and contribute to reducing the planar anisotropy. Erichsen tests showed that the Erichsen value of the sample with orthogonal four-peak texture increased up to ∼115% compared with that of the as-extruded sheet. This finding indicated that such a texture modification method was also highly conducive to enhancing the multiaxial stretch formability of the Mg sheets. The orthogonal four-peak texture modification was confirmed as an efficient way to improve the comprehensive mechanical performance of the Mg alloy sheets.

Cylindrical cup deep drawing of ZEK100 sheet at elevated temperatures

Cylindrical cup deep drawing experiments are performed on as-received magnesium rare-earth alloyed ZEK100 rolled sheet between room temperature and 250 °C. All tests are performed using warm tooling comprising a 101.6 mm (4”) diameter cylindrical punch and smooth die and blank holder. Both isothermal and non-isothermal experiments are performed with a draw ratio of 2.25. Warm temperature formability of ZEK100 is investigated through determination of draw depths of cylindrical cups under isothermal and non-isothermal conditions. The effect of sheet anisotropy during deep drawing operation is investigated by measuring the earring profiles by means of digital imaging as well as sheet thickness from the center to the outer diameter in the rolling direction. It is found that ZEK100 sheets exhibit significantly better warm temperature drawing performance over commercial wrought magnesium alloy sheet – e.g. a full draw of 203.2 mm (8”) blanks of ZEKIOO-O was achieved with tool temperature of 150 °C compared to a full draw for AZ31B-O with a tool temperature of 225 °C. Temperature process windows are used to present a direct comparison of forming behavior between ZEK100 and AZ31B. The increased forming performance of ZEK100 at elevated temperatures is attributed to the weakened texture resulting from alloying with Zr and Nd, respectively, allowing for elevated slip activity at lower temperatures.

Homogeneity improvement of friction stir welded ZK61 alloy sheets in microstructure and mechanical properties by multi-pass lowered-temperature rolling

Multi-pass lowered-temperature rolling was applied on the friction stir welded ZK61 magnesium alloy sheets not only for fabricating wide high-performance wrought magnesium alloy sheets, but also for reducing the sheet inhomogeneity including the microstructure and mechanical properties induced by friction stir welding. Results showed that obvious microstructure inhomogeneity including plannar texture anisotropy between the base metal and the stir zone were introduced in the friction stir welded ZK61 alloy sheets, but can be strikingly weakened by hot rolling deformation via multiple dynamic recrystallization. These led to a uniform fine-grained structure of about 8µm in average grain size and similar (0002) basal texture in the final 1.4mm thick sheets, and brought a continuous improvement in the associated property differences, where the relatively lower yield strength in base metal zone was strongly correlated with spreading (0002) texture while higher values in stir zone with stable intense (0002) texture. Moreover, the experimental and calculated Hall–Petch relationships were investigated to explain the different evolution of yield strength between the base metal and the stir zone. Meanwhile, enhanced fracture elongations larger than 20% in both the base metal zone and the stir zone were primarily attributed to grain refinement.

Effect of Deformation and Temperature Paths in Severe Plastic Deformation Using Groove Pressing on Microstructure, Texture, and Mechanical Properties of AZ31-O

Processing of wrought magnesium alloy sheet by severe plastic deformation (SPD) for improving its formability is attractive so as to encourage the wider applications of the alloy. In this study, SPD by means of groove pressing (GP) was carried out on AZ31B-O magnesium sheet at different deformation paths and temperatures in order to investigate its effects on microstructure, textures, and mechanical properties. GP using an orthogonal pressing at every cycle and at a progressively decreasing temperature was found to be effectively for manufacturing fine-grained microstructures with an average grain diameter of 1.9 μm. The final microstructures were homogenous in both the transverse direction (TD) and rolling direction (RD) and consisting of fine grains of 0.6–1 μm with a small fraction of coarser grains of 3–5 μm. The increase in yield stress (YS), ultimate tensile strength (UTS), and tensile elongation after annealing was 12%, −2.9%, and 25.6%, respectively, in the RD. A good balance between fine-grained microstructure and ductility was obtained by the pressing at a constant processing temperature of 473 K. In this pressing path, average grain diameter was 3.8 μm and the increased in YS, UTS, and tensile elongation before annealing was 21.9%, 9.1%, and 19.8%, respectively, in the RD. It was shown that the texture modification combined with fine-grained microstructure contributed to the overall improvement in ductility.

A 3D Finite Element Simulation of Cold Roll Forming of Wrought Magnesium Alloy Sheets

In recent several years, although production of magnesium has risen dramatically, production of magnesium alloy sheet remains still at a very low level in practical use. The major barrier to greatly increased magnesium alloy use has been in still primarily high manufacturing cost as well as poor work ability of wrought magnesium sheet alloys. One of the author has investigated in cold roll forming of magnesium alloy, however detailed forming characteristics of the wrought magnesium alloy sheets has not been clarified. The aim of the study is to confirm possibilities of practical use of wrought magnesium alloy by using told roll forming process. A three dimensional elasto-plastic analysis by finite element method (FEM) has been conducted to examine the shapes of cross section, spring back characteristics, bending strains and longitudinal membrane strain of magnesium alloy sheet and cold rolled steel sheet during forming.

Microstructure and mechanical properties of AZ31B magnesium alloy gas metal arc weld

Wrought magnesium alloy sheets were butt welded with gas metal arc welding process. Pores in the weld were investigated under different welding parameters, the causes of pore formation were systematically disposed, and the effects of porosity on the microstructure and mechanical properties of the joint were analyzed. The microstructure examination shows that the pores mainly appear close to the top or bottom part of the weld, and could connect to each other and lead to the formation of cracks in the welds. However, the pores can be controlled with proper welding parameters. The tensile testing results reveal that the average joint strength is close to or higher than that of the base metal. The microhardness in the weld can be even higher than that in the base metal due to the second phase strengthening of β-Mg17(Al, Zn)12 formed in the weld.

920 展伸用AZ31マグネシウム合金板材の冷間ロール成形特性

The growing demand for light weight products for automotive industries has been increased due to global trend of environmental preservation. In recent several years, although production of magnesium has risen dramatically, production of magnesium alloy sheet remains still at a very low level in practical use. The major barrier to greatly increased magnesium alloy use has been in still primarily high manufacturing cost as well as its poor workability of wrought magnesium sheet alloys. One of the author has investigated in cold roll forming of magnesium alloy, however detailed forming characteristics of the wrought magnesium alloy sheets has not been clarified. The aim of the study is to establish a guideline for roll design in the roll forming for wrought magnesium alloy sheet. A three dimensional elasto-plastic analysis by finite element method (FEM) has been conducted to examine the shapes of cross section, springback characteristics, bending strains and longitudinal membrane strain of magnesium alloy sheet and cold rolled steel sheet during forming.

Effects of Aluminum Content on Plastic Formability of Wrought Mg Alloy Sheet Produced by Twin-Roll Casting Process

A total weight reduction approach has been key issue for car manufacturers to cope with more and more stringent requirements for fuel economy. This paper describes the twin-roll casting technology of magnesium alloys that contain relatively high weight ratios of aluminum, such as AZ91,AZ101 and AZ111. The magnesium alloy sheets were cast by a horizontal twin roll caster to manufacture relatively high-strength Mg alloys with high aluminum content. The influences of such process parameters as casting temperature and roll speed were ascertained. The microstructures of cast magnesium alloy sheets were observed to investigate the effects of roll-casting conditions on crystal growth in the cast products. It was found that Mg alloys with high aluminum content can be fabricated at a roll speed of 15 m/min with a horizontal-roll caster. The grain size of the manufactured wrought magnesium alloy sheet was about 10 μm due to rapid solidification in the proposed process.

Microstructure and mechanical properties of Mg–Al–Mn–Ca alloy sheet produced by twin roll casting and sequential warm rolling

Microstructural evolution and mechanical properties of twin roll cast (TRC) Mg–3.3 wt.%Al–0.8 wt.%Mn–0.2 wt.%Ca (AM31 + 0.2Ca) alloy strip during warm rolling and subsequent annealing were investigated in this paper. The as-TRC alloy strip shows columnar dendrites in surface and equiaxed dendrites in center regions, as well as finely dispersed primary Al 8Mn 5 particles on interdendritic boundaries which result in the beneficial effect on microstructural refinement of strip casting. The warm rolled sheets show intensively deformed band or shear band structures, as well as finely and homogeneously dispersed Al–Mn particles. No evident dynamic recrystallization (DRX) takes place during warm rolling process, which is more likely attributed to the finely dispersed particle and high solid solution of Al and Mn atoms in α-Mg matrix. After annealing at 350 °C for 1 h, the warm rolled TRC sheets show fine equiaxed grains around 7.8 μm in average size. It has been shown that the present TRC alloy sheet has superior tensile strength and comparative elongation compared to commercial ingot cast (IC) one, suggesting the possibility of the development of wrought magnesium alloy sheets by twin roll strip casting processing. The microstructural evolution during warm rolling and subsequent annealing as well as the resulting tensile properties were analyzed and discussed.

Mechanical Properties and Metallurgical Qualities of High Aluminum Content Magnesium Alloys Fabricated by Twin-Roll Casting

This paper describes the twin-roll casting technology of magnesium alloys that contain relatively high weight ratios of aluminum, such as AZ91, AZ101 and AZ111. The magnesium alloy sheets were cast by a horizontal twin roll caster to manufacture relatively high-strength Mg alloys with high aluminum content. The influences of such process parameters as casting temperature and roll speed were ascertained. The microstructures of cast magnesium alloy sheets are observed to investigate the effects of roll-casting conditions on crystal growth in the cast products. It was found that Mg alloys with high aluminum content can be fabricated at a roll speed of 15 m/min with a horizontal-roll caster. The grain size of the manufactured wrought magnesium alloy sheet was about 10 micrometers due to rapid solidification in the proposed process.

Effect of Aluminum Content on Mechanical Properties of Cast Magnesium Alloy Sheets Fabricated by Twin-Roll Casting

This paper describes the twin-roll casting technology of magnesium alloys that contain relatively high weight ratios of aluminum, such as AM60, AZ91 and AZ121. The magnesium alloy sheets were cast by a vertical roll caster to manufacture relatively high-strength Mg alloys with high aluminum content. The influences of such process parameters as roll materials, casting temperature, and roll speed were ascertained. A simple method of predicting the convection heat transfer coefficient between casting rolls and molten metal is introduced. The microstructures of cast magnesium alloy sheets are microscopically observed to investigate the effects of roll-casting conditions on crystal growth in the cast products. It was found that Mg alloys with high aluminum content can be fabricated at a roll speed of 90m/min with a vertical-roll caster. The grain size of the manufactured wrought magnesium alloy sheet was about 30 micrometers due to rapid solidification in the proposed process.

Warm deep drawing of wrought magnesium alloy sheets produced by semi-solid roll strip-casting process

This paper is concerned with the development of a continuous strip-casting technology to facilitate the manufacture of magnesium sheet alloys economically whilst maintaining high quality. Established in the paper is warm formability of cast magnesium alloy sheets after being hot rolled by semi-solid roll strip-casting process. It has been found that magnesium sheet with 2.0–4.0 mm thickness could be produced at a speed of 25 m/min. Hot rolling and annealing temperatures during hot rolling were also changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microstructures of the crystals of the manufactured wrought magnesium alloys were observed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep-drawing test of the cast magnesium alloy sheets after being hot rolled.

Plane-Strain Fracture Toughness on Thin AZ31 Wrought Magnesium Alloy Sheets

There are few reports about plane-strain fracture toughness on wrought magnesium alloys. Also, there are a little data, for example plane-strain fracture toughness, that evaluates such as reliability and safety in magnesium alloys. Therefore, in this study, plane-strain fracture toughness, K IC , on thin AZ31 wrought magnesium alloy sheets was analyzed. As a result, appropriate plane-strain fracture toughness was not obtained by plane-strain fracture toughness test. It was because specimens used in this study were too thin to satisfy small scale yielding condition. But, as a result of stretched zone analysis, appropriate plane-strain fracture toughness, K IC , was obtained and the values of K IC were 16.5-18.4 MPam 1/2 . According to the result of this study, it is concluded that stretched zone analysis Was one of effective ways to evaluate fracture toughness of AZ31 wrought magnesium alloy appropriately. And the values of fracture toughness on AZ31 wrought magnesium alloys were equal or higher than that of cast magnesium alloy.