scholarly journals Microstructure Evolution and Mechanical Properties of AZ80 Mg Alloy during Annular Channel Angular Extrusion Process and Heat Treatment

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4223 ◽  
Author(s):  
Xi Zhao ◽  
Shuchang Li ◽  
Fafa Yan ◽  
Zhimin Zhang ◽  
Yaojin Wu

Microstructure evolution and mechanical properties of AZ80 Mg alloy during annular channel angular extrusion (350 °C) and heat treatment with varying parameters were investigated, respectively. The results showed that dynamic recrystallization of Mg grains was developed and the dendritic eutectic β-Mg17Al12 phases formed during the solidification were broken into small β-phase particles after hot extrusion. Moreover, a weak texture with two dominant peaks formed owing to the significant grain refinement and the enhanced activation of pyramidal <c + a> slip at relative high temperature. The tension tests showed that both the yield strength and ultimate tensile strength of the extruded alloy were dramatically improved owing to the joint strengthening effect of fine grain and β-phase particles as compared with the homogenized sample. The solution treatment achieved the good plasticity of the alloy resulting from the dissolution of β-phases and the development of more equiaxed grains, while the direct-aging process led to poor alloy elongation as a result of residual eutectic β-phases. After solution and aging treatment, simultaneous bonding strength and plasticity of the alloy were achieved, as a consequence of dissolution of coarse eutectic β-phases and heterogeneous precipitation of a large quantity of newly formed β-phases with both the morphologies of continuous and discontinuous precipitates.

2010 ◽  
Vol 137 ◽  
pp. 35-79 ◽  
Author(s):  
Mehdi Asadi ◽  
Nicole Schulze ◽  
Heinz Palkowski

This research deals with processes leading to local strengthening effects in Advanced High Strength Steels (AHSS). Dual phase (DP), retained austenite (RA) - both hot and cold rolled - and complex phase (CP) steels have been investigated to examine the effect of thermal and mechanical processing parameters on local properties. For this purpose, a method has been investigated to achieve local strengthening, namely local deformation and local heat treatment. Samples were locally deformed by bending and embossing processes. A local deformation with defined pre-strains leads to enhanced hardness and strengthening. A subsequent aging treatment leads to a further increase in mechanical properties. Local heat treatment was applied using a laser and an electron beam. Following local heat treatment with selected parameters, the microstructure of the surface and the cross section as well as the mechanical properties were evaluated by light optical, scanning as well as transmission electron microscopy, hardness measurement, tensile testing and thermal modelling. It can be stated that with partial heat treatment, local high strengthening can be produced. At lower heat treating temperatures, this effect could be attributed to bake hardening. With increased heat treating temperature, the initial microstructure near the surface is affected. A model can be improved, which defines the correlation between the influencing parameters and the local properties. The influence of over-aging in locally strengthen regions has been studied. For this investigation, parameters are stable to locally adjust the strengthening effect. Partial strengthening of AHSS by local deformation or local heat treatment can open up new fields of applications for locally using the strengthening effect to only influence relevant areas of interest, thus providing the potential for saving energy and designing the component’s behaviour.


2014 ◽  
Vol 881-883 ◽  
pp. 1317-1329 ◽  
Author(s):  
Mahmoud M. Tash ◽  
Saleh Alkahtani

The present study was conducted to investigate the effect of heat treatment on the aging and mechanical behavior of Al-Cu-Mg-Li-Zr , Al-Mg-Si and and Al-Mg-Zn alloys (8090 , 6082 and 7075). The effect of cold work after solution treatment, aging parameters (time and temperature) on the microstructure and mechanical properties were studied. Attempts are made to determine the combined effect of cold work and aging treatment on the hardness, UTS and microstructure for these alloys. By study the impact of different heat treatments for Al-Mg-Si alloys (6082), Al-Cu-Mg-Li-Zr (8090) and Al-Mg-Zn (7075) aluminum alloys on the hardness and mechanical properties, it is possible to determine conditions necessary to achieve better mechanical properties and the maximum levels of hardness and values corresponding to those considered suitable for commercial applications of these alloys.Design of Experiment (DOE) method in Minitab is used to measure the impact of various factors and how they relate. Correlation between the hardness and different metallurgical factors for these alloys at both quantitative and qualitative are investigated and analysed. A statistical design of experiments (DOE) approach using fractional factorial design was applied to determine the influence of controlling variables of cold work and heat treatment parameters and any interactions between them on the hardness of the above alloys. A mathematical model is developed to relate the alloy hardness with the different metallurgical parameters to acquire an understanding of the effects of these variables and their interactions on the hardness of wrought Al-alloys. It is noticed that cold work, following solution treatment, accelerates the precipitation rate leading to a rise in strength


2007 ◽  
Vol 567-568 ◽  
pp. 361-364 ◽  
Author(s):  
Suk Bong Kang ◽  
Jae Hyung Cho ◽  
Hyoung Wook Kim ◽  
Y.M Jin

The sheet of ZK60 alloy with a thickness of 1mm was prepared from a casting ingot followed by homogenization and warm-rolling. Variations in microstructure and mechanical properties of ZK60 alloy sheets were investigated during T6 treatment. Especially artificial aging after solution heat treatment affected both precipitates distribution and mechanical properties with aging treatment. Variations of mechanical properties were related to precipitates, i.e. rod-shaped ( 1 β ′ ) or disc shaped ( 2 β ′ ) particles. Around the peak of hardness values, regularly distributed rod-shaped ( 1 β ′ ) precipitates were found. The rod-shaped ( 1 β ′ ) precipitates were oriented with a growth direction of [0001]. When over-aged, rod-shaped ( 1 β ′ ) precipitates were expected to decrease and the density of disc-shaped ( 2 β ′ ) precipitates to change. The rod-shaped ( 1 β ′ ) precipitates mainly consist of {Mg, Zn}, while disc-shaped ( 2 β ′ ) precipitates, {Mg, Zn, Zr} or {Mg, Zn}. In this study the optimum T6 treatment was determined as solution treatment at 430 °C for 6 hours and subsequently aging treatment at 175 °C for 18 hours. At this T6 condition the tensile strength, yield strength and elongation are 321MPa, 280MPa and 16%, respectively.


2018 ◽  
Vol 929 ◽  
pp. 42-49
Author(s):  
Zuldesmi Mansjur ◽  
Hendro Maxwel Sumual

Beta type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) is one of the titanium alloys which have gained much attention in dental applications. Dental precision casting is predominant for fabricating dental prostheses. However, there is a possibility for the mechanical properties of its casting to be degraded because of a α case, shrinkages and pores and a dendrite structure. One of the ways to enhance their mechanical properties is heat treatment process. Therefore, the aim of this study is to investigate the effect of aging treatment on mechanical properties and microstructure of TNTZ cast into magnesia based mold in order to improve its mechanical properties. As results, the Vickers hardness of the cast TNTZ after solution treatment is larger than that of the wrought TNTZ. The aging curve of the cast and the wrought TNTZ at an aging temperature of 673 K and 723 K exhibit almost similar pattern. For each aging time, the higher the aging temperature, the smaller the Vickers hardness for both alloys. Microstructures of cast TNTZ at various aging conditions consist of a dendritic structure and the average diameters of their grain size are around 40 μm. The diffraction peaks of precipitation of α and β phase s are detected in under aging (UA), peak aging (PA) and over aging (OA) conditions for both aging temperatures. However, the diffraction peak of ω phase is observed only in OA condition for cast TNTZ at aging temperature of 673 K. The highest tensile strength of the cast TNTZ and the wrought TNTZ at both aging temperatures are in PA condition and the elongation decrease continuously by increasing aging time. The tensile strengths of cast TNTZ in UA, PA and OA conditions at an aging temperature of 723 K are lower and their elongations are higher in comparison with those of 673 K. The high oxygen content seems to contribute to the poor elongation. SEM fractographs of the cast TNTZ at aging temperatures of 673 and 723 K in UA, PA and OA conditions show the brittle morphology with intergranular fracture that increases with increasing of aging time.


2005 ◽  
Vol 488-489 ◽  
pp. 151-154
Author(s):  
Weichao Zheng ◽  
Xiao Li Sun ◽  
Peijie Li ◽  
Daben Zeng ◽  
L.B. Ber

Effect of heat treatment on the microstructure and mechanical properties of high purity MA2-1(Mg-5wt.%Al-1wt.%Zn-0.4wt.%Mn) alloy sheet were investigated. X-ray diffraction analysis indicated that the microstructure of high purity MA2-1 alloy sheet annealed consisted of α-Mg solid solution, β (Mg17Al12) phase and Al-Mn phases such as Al6Mn and Al10Mn3. β phase dissolved into α-Mg solid solution during the solution treatment and formed supersaturated α-Mg solid solution. After aging at the temperatures of 423 K, 473 K and 523 K for 12 hours, β phase precipitated from the supersaturated α-Mg solid solution. Optical microscope observation found that the grain size of the MA2-1 alloy sheet became larger after heat treatment. As a result, the mechanical properties of the MA2-1 alloy sheet such as the tensile strength and yield strength declined after the heat treatment.


2011 ◽  
Vol 467-469 ◽  
pp. 257-262
Author(s):  
Guo Fa Mi ◽  
Jin Zhi Zhang ◽  
Hai Yan Wang

Alloys were produced by casting of Cu-Al-Fe-Be and Cu-Al-Fe-Ni aluminum bronzes and aged. The microstructures and mechanical properties were evaluated. The results indicated that solution and aging treatment can significantly improve the plasticity of Cu-Al-Fe-Be and Cu-Al-Fe-Ni, while the strength and hardness remained in the quenched level. Extending the aging time can effectively enhance the mechanical properties of alloys, and the longer the aging time, the higher the electric resistance of alloys. According to the results, the mechanical properties of the Cu-Al-Fe-Be alloy can be improved remarkably by solution treatment for 120 min at 950°C, followed by aging treatment for 120 min at 350°C, and quenched. While the most suitable heat treatment for the Cu-Al-Fe-Ni alloy was solution treatment 120 min at 950°C, followed by aging for 120 min at 450°C, and quenched. The experimental result also suggested that the Cu-Al-Fe-Be alloy possessed higher hardness and tensile strength compared to the Cu-Al-Fe-Ni alloy.


2020 ◽  
Vol 321 ◽  
pp. 11046
Author(s):  
Xu Enen ◽  
Tian Yanwen ◽  
Hao Fang ◽  
Cu Linin ◽  
Du Yuxuan ◽  
...  

In this paper, the microstructure evolution and mechanical properties fluctuation of Ti-6Al-2Zr-1Mo-1V forging state bar after the first stage heat treatment at 950℃~955℃ and the second stage heat treatment at 760℃~840℃ were studied. In the first stage of heat treatment, the content of primary α and the tensile strength decreases with the increase of temperature, and the high temperature duration time is obviously prolonged. During the second stage of heat treatment, the metastable β phase precipitates third α phase, and with the increase of temperature, the tensile strength increases and the high temperature duration time prolongs.


Author(s):  
Yachao Wang ◽  
Jing Shi ◽  
Xiaoyang Deng ◽  
Shiqiang Lu

Graphene nanoplatelets (GNPs) have many outstanding properties, such as high mechanical strengths, light weight, and high electric conductivity. These unique properties make it an ideal filler material for various composites. On the other hand, the development MMNCs (metal matrix nanocomposites) through additive manufacturing (AM) processes has become a major innovation in the field of advanced structural materials, owing to shorter production lead time, less material waste, high production flexibility. It is of great innovativeness to have the attractive features combined to produce GNPs reinforced MMNCs using AM techniques. In addition, metal components produced by laser assisted additive manufacturing (LAAM) methods usually have inferior mechanical properties, as compared to the counterparts by the traditional metal forming processes. To achieve optimized mechanical properties, the obtained MMNCs are subjected to various post treatment routines and the effect of post heat treatment on material properties is investigated. In this study, pure Inconel 718 and GNPs reinforced IN718 with 1.1 vol.% and 4.4 vol.% filler material are fabricated by selective laser melting (SLM). Room temperature tensile tests are conducted to evaluate the tensile properties. Scanning electron microscopy (SEM) observations are conducted to analyze the microstructure of materials and to understand the reinforcing mechanism. It is found that fabrication of GNPs reinforced MMC using SLM is a viable approach. The obtained composites possess dense microstructure and enhanced tensile strength. The strengthening effect and mechanisms involved in the composites are discussed. Solution treatments at three levels of temperature (940, 980, and 1020°C) for 1 hour period are carried out to evaluate the effect of the heat treatment on the material microstructure and therefore the resulted mechanical properties of the composite material. The results of samples with and without heat treatment are also compared. The experiments results indicate that that addition of GNPs into Inconel 718 results in significant strength improvement. Moreover, at any volume content of reinforcement, higher solution treatment leads to lower strength, mainly due to coarsened microstructure. The addition of GNPs effectively inhibits the grain growth during the post heat process and the average grain size is significantly refined compared to unreinforced samples. Moreover, through the investigation of various strengthening mechanisms, it is found that Orowan strengthening effect is small and can be neglected for both as-built and heat treated conditions. Load transfer effect is the dominating strengthening effect among all contributors and solution treatment significantly reduces thermal mismatch strengthening.


Sign in / Sign up

Export Citation Format

Share Document