Effect of Heat Treatment on Microstructure and Mechanical Properties of A390 Alloy

2013 ◽  
Vol 652-654 ◽  
pp. 1049-1053 ◽  
Author(s):  
Bao Li ◽  
Zhi Feng Zhang ◽  
Zhi Gang Wang ◽  
Jun Xu ◽  
Qiang Zhu

In the present work, the effects of heat treatment on microstructure and mechanical properties of A390 alloy were investigated. The results show that the as-cast microstructure of A390 alloy mainly consists of primary silicon, α-Al, eutectic silicon and Al2Cu phase. The morphology of primary silicon is irregular polygonal block with sharp edges. Eutectic silicon exhibits a coarse plate-like and acicular morphology and the fishbone like Al2Cu phases are gathered at the grain boundary. During solution treatment, eutectic silicon undergoes fragmentation and spheroidization and T6 heat treatment has a profound effect on the dissolution of Cu and Mg. However, the morphology and size of primary silicon changes little. After the aging process, Al2Cu phases are precipited as lamellar morphology. As a result, the mechanical properties the heat treated A390 alloy increases significantly after T6 treatment.

2020 ◽  
Vol 26 (10) ◽  
pp. 1739-1749
Author(s):  
Saad Waqar ◽  
Jiangwei Liu ◽  
Qidong Sun ◽  
Kai Guo ◽  
Jie Sun

Purpose This paper aims to investigate the influence of different post-annealing cooling conditions, i.e. furnace cooling (heat treatment (HT) 1 – slow cooling) and air cooling (HT 2 – fast cooling), on the microstructure and mechanical properties of selective laser melting (SLM) built austenitic 316L stainless steel (SS). Design/methodology/approach Three sets of 316L SS samples were fabricated using a machine standard scanning strategy. Each set consists of three tensile samples and a cubic sample for microstructural investigations. Two sets were subsequently subjected to annealing HT with different cooling conditions, i.e. HT 1 and HT 2, whereas one set was used in the as-built (AB) condition. The standard metallographic techniques of X-ray diffraction, scanning electron microscopy and electron back-scattered diffraction were used to investigate the microstructural variations induced by different cooling conditions. The resultant changes in mechanical properties were also investigated. Findings The phase change of SLM fabricated 316L was observed to be independent of the investigated cooling conditions and all samples consist of austenite phase only. Both HT 1 and HT 2 lead to dissolved characteristic melt pools of SLM. Noticeable increase in grain size of HT 1 and HT 2 samples was also observed. Compared with AB samples, the grain size of HT 1 and HT 2 was increased by 12.5% and 50%, respectively. A decreased hardness and strength, along with an increased ductility was also observed for HT 2 samples compared with HT 1 and AB samples. Originality/value From previous studies, it has been noticed that most investigations on HT of SLM fabricated 316L were mainly focused on the HT temperature or holding time. However, the post-HT cooling rate is also an equally important factor in deciding the microstructure and mechanical properties of heat-treated components. Therefore, this paper investigates the influence of different post-annealing cooling conditions on microstructure and mechanical properties of SLM fabricated 316L components. This study provides a foundation for considering the post-HT cooling rate as an influential parameter that controls the properties of heat-treated SLM components.


2011 ◽  
Vol 197-198 ◽  
pp. 1524-1527 ◽  
Author(s):  
Hong Bo Dong ◽  
Xin Yang

The effects of heat treatment process on the microstructure and mechanical properties of TC4 alloy were investigated. The double shear and tensile tests were carried out by using the 12mm diameter standard specimens after solution treatment at 520°С for 1.5h and water quenching, followed by aging at 480-540°С for 8h. The microstructure and facture surface were analyzed using the equipment of metallurgical microscope and scanning electron microscopy. The results show that TC4 alloy show the best comprehensive performances after solution treatment at 940°С for 1.5h, aging at 520°С for 8h; the tensile specimens display a typical ductile fracture with oval dimples of various sizes; the microstructures with clear grain boundary and obvious lamellar structure are observed at room temperature. It indicates that the excellent comprehensive properties can be obtained by controlling the grain size of primary α phase and the morphology structure and amount of the secondary α phase at optimized aging temperature.


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.


Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 71
Author(s):  
Ho-Jung Kang ◽  
Jin-Young Park ◽  
Yoon-Suk Choi ◽  
Dae-Hyun Cho

Heat treatment is widely used to improve the properties of Al–Si–Mg alloys and its outcomes are influenced by the parameters applied during the treatment. This study describes the effect of the solution and artificial aging treatments on the microstructure and mechanical properties of die-cast Al–Si–Mg alloys. The microstructure of the as-cast Al–Si–Mg alloy was mainly composed of α-Al, complex needle-type eutectic Si particles, Mg2Si, and α-AlFeMn. The complex needle-type eutectic Si particles disintegrated into spheroidal morphologies, while the Mg2Si was dissolved due to the solid solution treatment. The maximum yield strength (YS) and ultimate tensile strength (UTS) values were 126.06 and 245.90 MPa at 520 °C after 90 min of solution heat treatment, respectively. Although the YS and UTS values of the Al–Si–Mg alloys reduced due to the solution treatment, the elongation (EL) of the solid solution heat-treated Al–Si–Mg alloys was improved in comparison to that of the as-cast Al–Si–Mg alloy. The maximum YS and UTS of 239.50 and 290.93 MPa were obtained after performing artificial aging at 180 °C for 180 min, respectively. However, the EL of the aging heat-treated alloy was reduced by a minimal value.


Author(s):  
Na Zhang ◽  
Hanwu Dong ◽  
Limin Wang ◽  
Renju Cheng ◽  
Jun Zhan ◽  
...  

Abstract Gadolinium (Gd) (up to 10 wt.%) was added to Mg-7Li dual-phase alloys, and the Gd-containing alloys were heat-treated for 3 h at 698 -748 K. The microstructure and mechanical properties of the as-cast and heat-treated alloys were then examined. The results indicated that the addition of Gd introduced the Mg3Gd phase into the duplex Mg-7Li alloy, containing a-Mg and b-Li phases. Gd also refined the grains, and the addition of 8 wt.% Gd resulted in the highest grain refining effect. The Gd atoms in the a-Mg phase, as well as precipitates in b-Li matrixes and at the surface of the a-Mg phase, strengthened the alloys. The highest strength alloy was obtained after the addition of 6 wt.% Gd, with tensile and compressive yield strengths of 143- 147 MPa, about twice as those of the Mg-7Li alloy. Heat treatment, which was found to be optimum at 723 K for 3 h, can decrease both the amount of precipitate and the hardness of the alloy, but not the amount of the Mg3Gd phase.


2011 ◽  
Vol 194-196 ◽  
pp. 1296-1300
Author(s):  
Xiao Song Li ◽  
Wei Hu ◽  
An Hui Cai ◽  
Hua Chen ◽  
Yong Zhou

The effect of the Sr + RE complex modifications on microstructure and mechanical properties of Al-40 wt% Si alloy were investigated. The results show that Sr + RE complex modification not only on primary silicon and eutectic silicon with modification, but also on dendrite α significantly refine. When the addition of RE remain unchanged, with increasing of the addition of Sr, the primary silicon firstly changes from polygonal block or large plate to small block, then to large polygonal block, edge and corner passivations. The eutectic silicon firstly changes into a fine start with a long needle-like fibrous or branched further to a short stubby dendrite or worm-like, The eutectic silicon changes from needle to a fibrous sheet plus short rod, then to short rod end for the dense, or even granular. The dendrite α changes from highly developed dendritic to equiaxed and uniform distribution. In addition, with increasing of the addition of Sr, the mechanical properties has been significantly improved, tensile strength increased by 37%, elongation is more than double, the hardness increased by 21%. When the Sr addition is between 0.05 wt% and 0.077 wt%, the microstructure and mechanical properties are the best.


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.


2013 ◽  
Vol 586 ◽  
pp. 137-140 ◽  
Author(s):  
Lenka Hurtalová ◽  
Eva Tillová ◽  
Mária Chalupová

Secondary aluminium alloys are made out of aluminium scrap and aluminium-processable waste by recycling. These alloys contain different alloying elements such as Al, Cu, Fe, Si and Mg that form intermetallic phases in aluminium matrix and influence on the microstructure, basic mechanical properties and microhardness evolution in aluminium cast alloy. As experimental material was used secondary aluminium cast alloy AlSi9Cu3. Material was subjected to heat treatment (age-hardening) consisting of a solution treatment at temperature 515 °C with holding time 4 hours, than water quenching at 40 °C and artificial aging by different temperature 130 °C, 150 °C and 170 °C with different holding time (2, 4, 8, 16 and 32 hours). The age-hardening led to changes in the morphology of structural components, but also leads to precipitation of finer hardening phases in the material substructure. As optimal age-hardening mode for secondary aluminium cast alloy AlSi9Cu3 was determined mode consisting of solution treatment at temperature 515 °C with holding time 4 hours and artificial aging at temperature 170 °C with holding time 16 hours. After this heat treatment cast alloy shows the best changes in microstructure and mechanical properties. These changes are comparable with changes by primary AlSi9Cu3 cast alloy.


2011 ◽  
Vol 197-198 ◽  
pp. 1125-1128 ◽  
Author(s):  
Jing Jiang Nie ◽  
Liang Meng ◽  
Xiu Rong Zhu ◽  
Yong Dong Xu ◽  
Yue Yi Wu ◽  
...  

The effect of the combined action of hot work and heat treatment on the microstructure and mechanical properties of a Mg-2Gd-Nd-0.4Zn-0.3Zr (wt. %) (E21) alloy was investigated. Results showed that the solution treatment time of the ingot played a great effect on the mechanical properties of the extruded alloy. With solution treating time of the ingot increasing, the tensile strength of the extruded alloy decreased gradually, but the elongation increased greatly. The best combination of strength and ductility was achieved for the extruded alloy after the ingot solution treated at 520°C for 3 h, extrusion at 400°C and aging at 200°C for 16 h, namely ultimate tensile strength = 331MPa and elongation = 7.1%.


2016 ◽  
Vol 877 ◽  
pp. 27-32
Author(s):  
Hai Tao Zhang ◽  
Dong Tao Wang ◽  
Ke Qin ◽  
Xing Han ◽  
Bo Shao ◽  
...  

The effect of phosphorus on primary silicon, phosphorus and mischmetal (Ce-50La) modification on primary and eutectic silicon and cooling rate on microstructure of Al-25%Si are investigated. The results show that, with the addition of phosphorus, the size of primary silicon decreases from 93.6μm to 24.75μm. The morphology of primary silicon changes from irregular to polygonal. When Al-25%Si is modified by phosphorus and mischmetal, primary and eutectic silicon all change effectively. Addition of mischmetal on the basis of phosphorus modification have no influence to primary silicon, but it can make morphology of eutectic silicon change from lamellar to short rod-like when the content of mischmetal reaches 0.5%. The cooling rate curves show the change of temperature in different height of wedge-shaped mould. When cooling rate increases, microstructure of Al-25%Si refines, the size of primary silicon decrease to 22.7μm. The results obtained from mechanical testing demonstrate that the addition of mischmetal and increasing of cooling rate increase hardness value of Al-25%Si alloy.


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