Excellent Room Temperature Formability Research Articles

Development of a New Magnesium Alloy with Excellent Room Temperature Formability, Heat Dissipation, and Corrosion Resistance

Development of a New Magnesium Alloy with Excellent Room Temperature Formability, Heat Dissipation, and Corrosion Resistance

Effect of Post-Heat Treatment Temperature on Interfacial Mechanical Properties of Cold-Rolled Ti/Al Clad Material.

Titanium and titanium alloys possess low density, high specific strength, and excellent corrosion resistance, but are expensive and have low formability at room temperature. Therefore, to reduce cost and achieve excellent properties, titanium and titanium alloys are jointed with aluminum and its alloys, which are inexpensive and have low density and excellent room temperature formability. Cladding is a widely used solid-state bonding technique, and the post-heat treatment of titanium/aluminum clad materials is required to improve their interfacial properties, which is important to ensure the reliability of Ti/Al-clad materials. The interfacial properties of Ti/Al-clad materials are significantly affected by changes in the microstructure and mechanical properties after the post-heat treatment. Thus, in this study, the relationship between the microstructure and mechanical properties at the interface of Ti/Al-clad materials was analyzed after the post-heat treatment at several different temperatures. The thick diffusion and intermetallic compound layer was formed with post-heat treatment owing to the active diffusion of Al atoms. As a result, their uniaxial and nanomechanical properties were varied with the interfacial characteristics of the Ti/Al-clad material.

Role of Zn on the room temperature formability and strength in Mg–Al–Ca–Mn sheet alloys

We clarified the role of Zn on the mechanical properties and texture evolution in Mg-1.2Al-0.5Ca-0.4Mn-xZn (wt.%, x = 0, 0.8 and 1.6) alloy sheets fabricated by twin-roll casting and hot rolling. The room temperature stretch formability of the solution-treated sheet is improved with increasing Zn content, x. The Mg-1.2Al-0.5Ca-0.4Mn-1.6Zn alloy shows excellent stretch formability with the largest Index Erichsen value of 8.2 mm due to a weak transverse direction split texture. The development of the transverse direction split texture is attributed to the preferential nucleation of recrystallized grains at double twin boundaries promoted by the moderate segregation of Zn and Al. Subsequent artificial aging at 170 °C for 2 h (T6) leads to a substantial increase in strength without loss of ductility. The peak-aged Mg-1.2Al-0.5Ca-0.4Mn-1.6Zn alloy exhibits a high tensile yield stress of 210 MPa with an excellent elongation of 30.1% because of the dense dispersion of Guinier Preston zones within the Mg matrix. The insights gained in this work would establish a base for rational design and fabrication of bake-hardenable magnesium alloy sheet with excellent room temperature formability and high strength.

A new magnesium sheet alloy with high tensile properties and room-temperature formability

Lightweight sheet alloys with superior mechanical performance such as high strength, ductility and formability at room temperature (RT) are desirable for high volume automotive applications. However, ductility or formability of metallic alloys at RT are generally inversely related to strength, thereby making it difficult to optimize all three simultaneously. Here we design a new magnesium sheet alloy-ZAXME11100 (Mg-1.0Zn-1.0Al-0.5Ca-0.4Mn-0.2Ce, wt. pct.) via CALPHAD (CALculation of PHAse Diagram) modeling and experimental validation. This new sheet alloy offers an excellent RT formability with a high Index Erichsen (I.E.) value of 7.8 mm in a solution-treated condition (T4), due to its weak and split basal texture and fine grain structure. The new ZAXME 11100 alloy also shows a rapid age-hardening response during post-forming artificial aging treatment at 210 °C for 1 hour (T6), resulting in a significant increase of yield strength from 159 MPa (T4) to 270 MPa (T6). The excellent combination of T4 ductility (31%), T4 formability (7.8 mm) and T6 yield strength (270 MPa) in this new magnesium alloy is comparable to that of common 6xxx series aluminum sheet alloys. Thus, this new magnesium sheet alloy is highly attractive for sheet applications in automotive and other industries.

A combined experimental and numerical study on room temperature formable magnesium–silver–calcium alloys

Abstract This work investigated effects of silver (Ag) content on the microstructure, texture and mechanical properties of magnesium–silver–calcium alloys by a combined experimental and numerical approach. A series of ternary magnesium–silver–calcium alloys with Ag concentrations between 0.3 and 12 wt% were prepared by hot-extrusion, hot-rolling followed by annealing. As-rolled sheets showed rolling direction split textures with double peaks irrespective of the Ag content. A new component where (0002) basal poles tilted from the normal direction toward the transverse direction (TD) appeared when the Ag content was increased to 1 wt% after annealing. The Mg–xAg–0.1Ca (x = 0.3, 1, 2 and 3) alloys showed excellent room temperature (RT) formability, which could be mainly ascribed to weak basal textures developed after annealing. When the Ag content was increased to 6 wt%, a weak TD-split texture with a homogeneous fine-grained microstructure was developed, which resulted in excellent RT formability and high strength. In contrast, the Mg–12Ag–0.1Ca alloy showed much lower RT formability and ductility in comparison with Mg–Ag–Ca alloys with lower Ag concentrations due to the presence of coarse AgMg4 particles. Visco-plastic self-consistent simulation results revealed that the activity of prismatic slip was increased with increasing the Ag content and the enhanced activity of prismatic during rolling may partially lead to the formation of TD-split texture in the formable Mg–Ag–Ca alloys during annealing.

A room temperature formable magnesium–silver–calcium sheet alloy with high ductility

A newly developed magnesium sheet alloy, Mg–1.5Ag–0.1Ca in wt.%, shows a large index Erichsen value of 8.6 mm with a large average elongation to failure of 33% at room temperature (RT). The excellent RT formability and ductility are associated with a weak ring-like basal texture.

Bake-hardenable Mg–Al–Zn–Mn–Ca sheet alloy processed by twin-roll casting

Mg–1.3Al–0.8Zn–0.7Mn–0.5Ca (wt.%) (AZMX1110) alloy sheet produced by low-cost twin-roll casting process exhibits excellent room temperature formability with a large Index Erichsen (I.E.) value of 7.8 mm at room temperature in a solution treated condition (T4). The large I.E. value is associated with a weak basal texture in the T4-condition. This alloy shows rapid age-hardening response at 170 °C, resulting in a significant increase of the flow stress from 198 MPa to 238 MPa within 20 min; such bake hardenability (BH) has never been explored in magnesium sheet alloys before. The microstructure of the bake-hardened sample, characterized by a correlative transmission electron microscopy and atom probe tomography (TEM-APT), reveals that Al, Zn and Ca atoms are segregated to basal <a> dislocations and contribute to the strengthening by pinning dislocation motions, along with the co-clustering of these atoms. This first BH Mg sheet alloy composed of only ubiquitous elements is highly attractive for application to automotive bodies.

Consideration of Castability and Formability for New Magnesium Alloys

A comprehensive consideration based on castability or plastic formability, as well as mechanical properties for development of either cast magnesium alloys or wrought magnesium alloys is a very important issue. To develop new magnesium alloy sheets with high formability at room temperature, the microstructure, texture, ductility and anisotropy of rolled Mg-Zn-Gd alloy sheets were investigated. The sheets exhibit an excellent ultimate elongation of nearly 50% and an uniform elongation greater than 30% with a very low planar anisotropy. The new sheet has a random basal texture and the basal pole is tilted by maximum 40° from the normal direction towards the transverse direction. The majority of grains in the tilted texture have an orientation favorable for both basal slip and tensile twining because of their high Schmid factor. The low planar anisotropy, the large uniform elongations and the high strain hardening rate observed in the Mg-Zn-Gd sheets result in excellent room temperature formability, the Erichsen values reach ~8, well comparable with the conventional aluminum alloys sheets at room temperature. The solidification pathways and phase equilibria of Mg-Al-Ca alloys have been profoundly investigated by using thermal analysis and thermodynamic calculations. The relationship between hot tearing tendency and alloy compositions were discussed in terms of strength of the mushy zone, solidification pathways and feeding mechanisms, et al. Thixoforming refers to as that metal components are formed in their semi-solid state. Criteria for thixoforming are summarized and then the thixoformability of Mg-Al-Ca based alloys (AC alloys) are evaluated using the thermodynamic calculations based on the consideration of metallurgical parameters.

Room-temperature ductility and anisotropy of two rolled Mg–Zn–Gd alloys

To develop new magnesium alloy sheets with high formability at room temperature, the microstructure, texture, ductility and anisotropy of rolled Mg–1%Zn–1%Gd and Mg–2%Zn–1%Gd sheets were investigated. The microstructures were characterized as fully recrystallized grains with a large amount of homogeneously distributed fine particles in the matrix. The sheets exhibit an excellent ultimate elongation of nearly 36% and an uniform elongation greater than 15%. The Mg–1%Zn–1%Gd sheet has a random basal texture and the basal pole is tilted by about 30° from the normal direction towards the transverse direction. The planar anisotropy is shown to be as low as 0. The flow curves of the two Mg–Zn–Gd alloys display an abrupt yielding with a remarkable linear hardening at high strain rate after a plastic strain of roughly 3%. The majority of grains in the tilted texture have an orientation favorable for both basal slip and tensile twining because of a high Schmid factor. The low planar anisotropy, the large uniform elongations and the high strain-hardening rate observed in the Mg–Zn–Gd sheets imply excellent room temperature formability.