Observations on Dynamic Strain Aging Manifestation in Inconel 718 Superalloy

2018 ◽  
Vol 930 ◽  
pp. 390-394 ◽  
Author(s):  
Monica Costa Rezende ◽  
Leonardo Sales Araújo ◽  
Sinara Borborema Gabriel ◽  
Jean Dille ◽  
Luiz Henrique de Almeida
Keyword(s):  
Dynamic Strain Aging ◽  
Inconel 718 ◽  
Strain Aging ◽  
Aging Treatment ◽  
Tensile Tests ◽  
Dynamic Strain ◽  
Dynamic Precipitation ◽  
Intergranular Cracking ◽  
Thermally Activated ◽  
Inconel 718 Superalloy

The manifestation of dynamic strain aging (DSA) in Inconel 718 is reported in this work. Analysis were performed in the material with different microstructures resulting from solution anneal and aging treatment. Tensile tests were made under secondary vacuum with temperature ranging between 200 and 950°C and strain rates of 3.2 x 10-3 to 3.2 x 10-5 s-1. Results showed the range of DSA occurrence. Analysis indicates that at lower temperatures, from approximately 200 to 450°C, serrations are controlled by the diffusion of carbon. At higher temperatures, until 800°C, DSA coincided with the occurrence of other thermally activated phenomena: dynamic precipitation, especially γ’’, and Oxidation Assisted Intergranular Cracking (OAIC). It was observed that competitive phenomena affect DSA manifestation directly due to the availability of niobium in solid solution.

Effects of Strain Rate on Dynamic Strain Aging of SA508-III Steel

2014 ◽  
Vol 788 ◽  
pp. 334-339 ◽  
Author(s):  
Dan Yuan ◽  
Lei Wang ◽  
Yang Liu ◽  
Xiu Song ◽  
Jia Hua Liu
Keyword(s):  
Strain Rate ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Cell Structure ◽  
Tensile Tests ◽  
Dislocation Cell ◽  
Strain Rate Range ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Reduction Of Area

The dynamic strain aging (DSA) behavior of SA508-III steel was evaluated through tensile tests with different strain rates from 10-4 to 10-1s-1 at 350°C. The OM, SEM and TEM were carried out to observe the microstructures and fracture morphologies of the steel. The results show that the serrated flows appear in the stress-strain curves when the strain rate is between 10-3~10-2s-1, indicating that DSA occurs. Under the strain rate range, the tensile strength increases and the elongation and the reduction of area decrease. However, the fracture surface of the steel after tensile tests is still ductile. DSA in SA508-III steel at the strain rates from10-3 to 10-2s-1 is mainly caused by the interaction between the internal solute atoms and dislocations, which leads to the dislocations multiplication and the formation of sub-grain boundaries and dislocation cell structure.

Dynamic Strain Aging in the Fe-Mn-Cu-C TWIP Steels

2013 ◽  
Vol 668 ◽  
pp. 861-864 ◽  
Author(s):  
Hai Jun Liu ◽  
Ding Yi Zhu ◽  
Xian Peng ◽  
Zhen Ming Hu ◽  
Ming Jie Wang
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Dynamic Strain ◽  
Work Hardening Rate ◽  
Twip Steels ◽  
High Work

Strain rate jump tests were performed on the Fe-Mn-Cu-C TWIP Steels to determine the strain rate sensitivity, and serrated plastic flow was observed in the stress-strain curves during tensile tests at different constant strain rates ranging from 2.5×10-4S-1 to 2.5×10-2S-1. The Fe-Mn-Cu-C TWIP Steels exhibit high work hardening rate and outstanding mechanical properties, The excellent mechanical properties are attributed to dynamic strain aging(DSA) effect, which result from the interaction between Mn(Cu)-C atom atmosphere, C-vacancy, C-C pairs and moving dislocations.

scholarly journals Effect of Dynamic Strain Aging on the Plastic Anisotropy and Mechanical Properties of Low-Carbon Phosphorus Steels

1978 ◽  
Vol 3 (1) ◽  
pp. 37-51
Author(s):  
W. A. Spitzig ◽  
Hsun Hu ◽  
R. J. Sober
Keyword(s):  
Mechanical Properties ◽  
Dislocation Density ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Plastic Anisotropy ◽  
Aging Treatment ◽  
Dynamic Strain ◽  
Low Carbon ◽  
Tension Testing ◽  
Subsequent Deformation

The effects of a dynamic-strain-aging treatment, as compared with a static-strain-aging treatment, on plastic anisotropy and mechanical properties has been determined for vacuum-melted low-carbon phosphorus steels containing various amounts of silicon. It was found that prestraining at 185°C, as compared with straining at 22°C followed by aging for four hours at 100°C, resulted in about twice the increase in yield strength (90 versus 48 MPa) on subsequent tension testing at 22°C and an improvement in rm values from about 1.8 to 2.0.Analyses of the textures and dislocation structures of the steels after the two strain-aging treatments and after subsequent deformation at 22°C showed that a greater dislocation density gives rise to the greater strengthening of dynamic-strain-aged specimens, and a finer polyhedral network of dislocation tangles is believed to be the reason for their higher rm values.

scholarly journals Effect of Alloying Elements and Microstructure on the Dynamic Strain Aging Behavior of 1.25Cr-0.5Mo and 2.25Cr-1Mo Steels

2021 ◽  
Vol 59 (11) ◽  
pp. 769-780
Author(s):  
Yo Seob Lee ◽  
Ho Jung Lee ◽  
Jong Hyeon Lee
Keyword(s):  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Tensile Tests ◽  
Alloying Elements ◽  
Solid Solution Hardening ◽  
Dynamic Strain ◽  
Air Cooling ◽  
Temperature Range ◽  
Cooling Conditions ◽  
Effect Of Alloying

The effect of alloying elements and microstructure on the dynamic strain aging (DSA) behavior of 1.25Cr-0.5Mo (P11, ASTM 335Gr.P11) and 2.25Cr-1Mo (P22, ASTM 335Gr.P22) steels was investigated. For both steels, different cooling conditions such as air-cooling (AC) and oil-quenching (OQ) were applied. Tensile tests were conducted in the temperature range of 20-450 ℃ and a strain rate in the range of 6 × 10-5- 6 × 10-3 s-1 for the steels with different cooling conditions. The P11AC steel showed serration behavior over a wider temperature range and exhibited higher ultimate tensile strength (UTS) than for the P22AC steel. This is attributed to the effects of alloying elements (Cr, Mo and Si) due to dissolved C, and the ferrite fraction on mechanical behavior. Meanwhile, the P11AC and P11OQ steels also showed different behaviors for DSA starting temperature, DSA temperature range, and serration type. The AC condition showed higher UTS from the interaction solid solution hardening (ISSH) effect due to substitutional Cr, Mo, and interstitial C elements. The calculated activation energy value (Q) for the P11 steel was around 94-103 kJ/mol-1, similar to that of ferritic steels, and it was higher for the P22 steel, with a Q value of 233 kJ/mol-1 from the ISSH effect.

scholarly journals A New Explanation for the Effect of Dynamic Strain Aging on Negative Strain Rate Sensitivity in Fe–30Mn–9Al–1C Steel

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3426 ◽  
Author(s):  
Jia Xing ◽  
Lifeng Hou ◽  
Huayun Du ◽  
Baosheng Liu ◽  
Yinghui Wei
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Dislocation Arrangement ◽  
Hall Plot

In this study, the evolution of the mechanical properties of Fe–30Mn–9Al–1C steel has been determined in tensile tests at strain rates of 10−4 to 102 s−1. The results show that the strain rate sensitivity becomes a negative value when the strain rate exceeds 100 s−1 and this abnormal evolution is attributed to the occurrence of dynamic strain aging. Due to the presence of intergranular κ-carbides, the fracture modes of steel include ductile fracture and intergranular fracture. The values of dislocation arrangement parameter M were obtained using a modified Williamson–Hall plot. It has been found that once the strain rate sensitivity becomes negative, the interaction of dislocations in the steel is weakened and the free movement of dislocation is enhanced. Adiabatic heating promotes the dynamic recovery of steel at a high strain rate.

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