scholarly journals Deformation Mechanism Investigation on Low Density 18Mn Steels under Different Solid Solution Treatments

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1497
Author(s):  
Yong-Tao Huo ◽  
Yan-Lin He ◽  
Na-Qiong Zhu ◽  
Min-Long Ding ◽  
Ren-Dong Liu ◽  
...  

To meet the demand of the 10% weight reduction goal for automotive steel, the microstructure and mechanical properties of Fe-18Mn-Al-C steel with different carbon and aluminum contents were investigated under different solid solution treatments, and the deformation mechanisms of the experimental steels were elucidated. Aided by thermodynamic calculation, transmission electron microscopy (TEM) and in situ scanning electron microscope (SEM) analysis, it was shown that for the 18Mn-1.5Al experimental steel with about 20 mJ/m2 stacking fault energy (SFE), the twinning-induced plasticity (TWIP) effect always dominated in this steel after different solid solution treatments under tensile deformation. With the 7 wt% aluminum addition, the SFE of austenite was affected by temperature and the range of SFE was between 60 and 65 mJ/m2. The existence of δ-ferrite obviously inhibited the TWIP effect. With the increase in the solution treatment temperature, δ-ferrite gradually transformed into the austenite, and the n-value remained low and stable in a large strain range, which were caused by the local hardening during the tensile deformation. Due to the difference in the deformability of the austenite and δ-ferrite structure as well as the inconsistent extension of the slip band, the micro-cracks were easily initiated in the 18Mn-7Al experimental steel; then, it exhibited lower plasticity.

2011 ◽  
Vol 378-379 ◽  
pp. 744-747 ◽  
Author(s):  
Jeong Min Kim ◽  
Joon Sik Park ◽  
Ho Seob Yun ◽  
Seung Jin Lee ◽  
Seong Uk An

Cast IN738LC alloy mainly consists of primary gamma matrix, gamma prime precipitates, and carbides. SEM-EDS analysis results suggested that most of the carbides are MC type ones that possess high Ti or Ta contents. MC carbides were partly dissolved into the matrix during the solid solution treatment, and the morphology and size of carbides were influenced by the solid solution treatment temperature. Characteristics of gamma prime precipitates were also significantly affected by the solid solution treatment conditions. Single or duplex size distributions of gamma prime precipitates were obtained depending on the solid solution treatment condition. Higher tensile strength was obtained in the case of finer precipitation size and in the case of single size distribution as compared with that of duplex size distribution.


2016 ◽  
Vol 879 ◽  
pp. 653-658
Author(s):  
Ju Hyun Won ◽  
Seok Hong Min ◽  
Tae Kwon Ha

Effect of B addition on the microstructure and mechanical properties of AZ84 Mg alloy was investigated in this study. Through calculation of phase equilibria of AZ84 Mg alloy, carried out by using FactSage® and FTLite database, solution treatment temperature was decided as temperature of 330oC, where supersaturated solid solution can be obtained. Solid solution treatment of AZ84 Mg alloy was successfully conducted at 330oC and supersaturated microstructure with all almost all phases resolved into matrix was obtained. After solution treatment, hot rolling was successfully conducted by reduction of 60%. Compression and tension tests were carried out at room temperature on the samples in as-cast, solution treated, hot-rolled and subsequently recrystallized states. After solid solution treatment, each alloy was soaked at temperatures of 180 and 200oC for time intervals from 1 min to 48 hrs and hardness of each condition was measured by micro-Vickers method. Peak aging conditions were deduced as at the temperature of 200 oC for 10 hrs for ZA84 Mg alloy. By addition of boron, aging kinetics was expedited and strength was enhanced.


2014 ◽  
Vol 988 ◽  
pp. 145-150
Author(s):  
Jian Chen ◽  
Ming Zhang ◽  
Dong Yang ◽  
Huan Liang

CuNiCoBe alloy and CuCoBe alloy were cast by the vacuum inductive melting technique, and were heat treated under certain parameters. By using optical microscope, sclerometer and conductivity meter, the properties of two alloys were investigated after heat treatment. Experimental results show that the process of 980 °C for solid solution and three hours of aging at 450 °C is the best heat treatment for CuCoBe alloy, while 960 °C is the best solid solution treatment temperature for CuNiCoBe alloy with the same aging measures. Ni is beneficial to improve the hardness and conductivity of alloys, and CuNiCoBe alloy has better strength, hardness and conductivity than CuCoBe alloy at different temperatures, and two alloys all have a conductivity mutation increase near 450 °C. CuNiCoBe alloy and CuCoBe alloy soften respectively at 464 °C and 471 °C.


2011 ◽  
Vol 695 ◽  
pp. 405-408 ◽  
Author(s):  
Ho Seob Yun ◽  
Joon Sik Park ◽  
Seong Uk An ◽  
Jeong Min Kim

It was observed that both primary and secondary gamma prime precipitates were more significantly influenced by the solid solution treatment temperature as compared to the following cooling rate. Single and duplex size precipitate distribution with different average size could be obtained through the appropriate solid solution and aging treatment. Micro-hardness test result indicated that single size distribution of gamma prime precipitates provides higher hardness than duplex size distribution.


2016 ◽  
Vol 852 ◽  
pp. 22-27
Author(s):  
Ming Bo Wang ◽  
An Gang Ning ◽  
Hai Ding Liu ◽  
Yong You Li ◽  
Dong Zhe Wang ◽  
...  

The effects of different solid-solution temperature and holding time on the alloy structure and mechanical properties of alloy 718 were investigated. The results show that the grain size grows up as the solid-solution temperature elevates and the holding time prolongs. The grain size increases slowly because undissolved delta phase restrains the growth of grains when solid-solution temperature is below 1000°C, whereas the grain size increases quickly when solid-solution temperature is beyond 1050°C. At room temperature, the strength and hardness of alloy 718 decrease with solution treatment temperature increasing, however, the ductility and toughness of alloy 718 both increase, and the brittle fracture of sample turns into ductile fracture.


2000 ◽  
Vol 15 (11) ◽  
pp. 2571-2576 ◽  
Author(s):  
Shogo Komura ◽  
Zenji Horita ◽  
Minoru Furukawa ◽  
Minoru Nemoto ◽  
Terence G. Langdon

Ultrafine grain sizes, of the order of approximately 0.2 μm, may be introduced into Al–Mg–Sc alloys by subjecting the material to severe plastic deformation through the process of equal-channel angular pressing (ECAP). Experiments were conducted to evaluate the influence of the solution treatment temperature on the ductility of an Al–3% Mg–0.2% Sc alloy after ECAP. The results show the highest ductilities are achieved when the solution treatment temperature is within the narrow range of approximately 878 to about 883 K, immediately below the temperature associated with the onset of partial melting. These high temperatures serve to maximize the amount of scandium in solid solution and this leads, on subsequent heating, to an extensive precipitation of fine secondary Al3Sc particles which inhibit grain growth at the higher temperatures. Conversely, solution treatments at temperatures below approximately 878 K give less Sc in solid solution within the matrix and the precipitation of the Al3Sc particles is then insufficient to retain a uniform ultrafine microstructure.


2013 ◽  
Vol 711 ◽  
pp. 87-90
Author(s):  
Yin Hui Yang

A commercial 2507 duplex stainless steel with different solution treatments followed by aging at 850°C has been investigated. At the early aging time of 850°C, the σ-phase precipitate was predominantly distributed at the δ/γ interface, as the isothermal aging time was increased to 150 min, more σ-phase precipitate formed in ferrite and became coarser by a eutectoid reaction δσ+γ2. The amount of δ-ferrite decreased rapidly at the beginning of aging for 80 minutes, increasing solution treatment temperature from 1060°C to 1230°C delayed decomposition of δ-ferrite due to lowering σ-phase formation element (Cr). The reaction rate K and σ-phase precipitation rate were lowered by increasing solution treatment temperature from 1060°C to 1230°C.


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