Manasij Yadava - Academia.edu (original) (raw)

Papers by Manasij Yadava

Journal of alloys and compounds, Apr 1, 2024

Science and Technology of Welding and Joining, 2010

Thinning in friction stir lap joints and its relation with the process variables was investigated... more Thinning in friction stir lap joints and its relation with the process variables was investigated. Friction stir welds were made on 1 mm thick AA6111 aluminium alloy sheets in order to study the effects of rotation rate, traverse speed, plunge depth, tilt angle and pin height on faying surface defects. Sheet thinning on the advancing and retreating sides was quantified and the lap shear strength of the joints was evaluated. A decrease in the pitch of the runs at constant rotation rate increased the sheet thinning and reduced the joint strength in a linear manner. Process pitch and pin height were found to be the most critical factors in determining the faying surface lift up. A pin of the same height as the sheet thickness resulted in maximum lap shear strength. Tool tilt did not show a significant effect on the sheet thinning.

Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic... more Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine

Materials Science and Technology, Jan 20, 2019

ABSTRACT The rate sensitivity of multiple obstacle aluminium alloy system was measured using the ... more ABSTRACT The rate sensitivity of multiple obstacle aluminium alloy system was measured using the stress relaxation method. A discrepancy was observed between the slope of the Haasen plot (rate sensitivity of dislocation–dislocation interaction) in pure metals and in alloys strengthened by multiple obstacles. Considering a simplifying assumption of the constant obstacle force–distance profile, it is suggested that slope of the Haasen plot is governed by glide dislocations’ length taking part in a thermally activated event. The relative strength and spacing of obstacles (forest dislocations, solutes and precipitates) is proposed to affect the thermally activated dislocation length, which in turn manifests as the difference in slope of the Haasen plot.

Materials Chemistry and Physics, Sep 1, 2018

In the present work, a criterion based on relation between strain hardening rate and rate of chan... more In the present work, a criterion based on relation between strain hardening rate and rate of change in activation volume is proposed for predicting formation of shear bands. The proposed criteria is validated by tracking changes in orientation distribution function (texture) as a function of shear band formation. The propensity of shear banding and its relation with operative rate controlling deformation mechanism is additionally discussed.

Metallurgical and Materials Transactions, Apr 26, 2018

Deformation behavior of an Al-Cu-Li alloy in different temper conditions (solutionized and T8) is... more Deformation behavior of an Al-Cu-Li alloy in different temper conditions (solutionized and T8) is investigated using stress relaxation tests. Fundamental parameters such as the apparent and physical activation volume, strain rate sensitivity, effective stress, and exhaustion rate of mobile dislocation density are determined from single and multiple relaxation tests. It was found that dislocation-dislocation interaction controls the kinetics of plastic deformation in the solutionized sample, whereas dislocation-precipitate interaction is the overriding factor in the presence of T 1 precipitates. The apparent activation volume was found to be significantly lower in the presence of T 1 precipitates compared with solutionized samples. Strain rate sensitivity and effective stress were found to be higher in the presence of T 1 precipitates. In addition, multiple relaxation tests showed that irrespective of microstructural features (solutes, semi-coherent precipitates), the mobile dislocation density reduces during the relaxation period. Further evidence regarding reduction in mobile dislocation density is obtained from uniaxial tensile tests carried out after stress relaxation tests, where both solutionized and T8 samples show an increase in strength. Additional discussion on relaxation strain is included to provide a complete overview regarding the time-dependent deformation behavior of the Al-Cu-Li alloy in different temper conditions.

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Jun 1, 2018

To reveal rate sensitive behavior of different obstacles observed in age hardenable aluminum allo... more To reveal rate sensitive behavior of different obstacles observed in age hardenable aluminum alloys, activation volume was measured as a function of flow stress. It was observed that solutes and precipitates are more rate sensitive compared to dislocations. Shearable precipitates were observed to be more rate sensitive amongst all obstacles.

Metallurgical and Materials Transactions, Jun 12, 2019

Materials Science and Technology, Aug 20, 2018

In the present work, a systematic investigation of crystallographic texture evolution and strain ... more In the present work, a systematic investigation of crystallographic texture evolution and strain hardening behaviour was undertaken to comprehend the deformation behaviour in the presence of T 1 (Al 2 CuLi) precipitates. Characteristic texture components symbolising multiple slip condition such as Copper and S were observed upon rolling which is in contrast with other Al alloys containing shearable precipitates. Strain hardening ability was also observed to be remarkably high in the presence of T 1 precipitates. The texture and strain hardening results are compared with another age hardenable Al alloy (Al-Mg-Si alloy) containing shearable precipitates to clearly bring out the difference in the nature of T 1 precipitates.

Metallurgical and Materials Transactions, Jan 29, 2020

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Jun 1, 2022

Social Science Research Network, 2022

Material flow and microstructure evolution are the two important aspects of the Friction stir wel... more Material flow and microstructure evolution are the two important aspects of the Friction stir welding (FSW) technique, which control the properties and performance of the friction stir welds. The present work investigates these two aspects of the FSW with main emphasis on the friction stir lap joints (FSLJs) on the AA6111 sheets. Due to the characteristic material flow during FSW, the faying surfaces in FSLPs are deposited in and around the weld nugget and create unavoidable defects. These defects reduce the load carrying thickness of the joints by providing an easy path for the weld failure. Therefore, to control the faying surface defects, a clear understanding of the material flow in FSW and its effect on the FSLJs is needed. With this objective, a comprehensive study of the material flow during FSLJs and the effects of various process parameters on the faying surface defects were conducted. This study not only revealed the mechanism of the formation of the faying surface defects but also explained the detailed material flow in the FSW. This investigation was further extended to study the role of FSW tool features on the material flow and the tool features to control the faying surface defects were proposed. The microstructure evolution during the FSW of AA6111 was investigated by differential scanning calorimetry (DSC), microhardness and transmission electron microscopy (TEM) techniques. This study showed that the increase in the heat input during FSW resulted in better aging response of the joints. The microhardness and strength variation across the FSW weld were explained from the DSC and TEM observations --Abstract, page iv

Social Science Research Network, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Materials Chemistry and Physics, May 1, 2019

Abstract In the present work, development of rolling texture in the presence of shearable precipi... more Abstract In the present work, development of rolling texture in the presence of shearable precipitates is analyzed using age hardenable aluminum magnesium silicon alloy (AA 6061) and aluminum-copper-lithium alloy (AA 2195). A characteristic Brass type texture evolves upon rolling of AA 6061 alloy containing β’’ (Mg5Si6) precipitates, whereas an unexpected Copper type texture develops upon rolling of AA 2195 alloy containing T1 (Al2CuLi) precipitates. The present work highlights that rolling texture evolution in the presence of shearable precipitates cannot be generalized and depends strongly upon the shearing propensity of these precipitates.

Modelling and Simulation in Materials Science and Engineering, Jun 14, 2018

Journal of Materials Engineering and Performance, Aug 19, 2021

Social Science Research Network, 2022

Journal of alloys and compounds, Apr 1, 2024

Science and Technology of Welding and Joining, 2010

Thinning in friction stir lap joints and its relation with the process variables was investigated... more Thinning in friction stir lap joints and its relation with the process variables was investigated. Friction stir welds were made on 1 mm thick AA6111 aluminium alloy sheets in order to study the effects of rotation rate, traverse speed, plunge depth, tilt angle and pin height on faying surface defects. Sheet thinning on the advancing and retreating sides was quantified and the lap shear strength of the joints was evaluated. A decrease in the pitch of the runs at constant rotation rate increased the sheet thinning and reduced the joint strength in a linear manner. Process pitch and pin height were found to be the most critical factors in determining the faying surface lift up. A pin of the same height as the sheet thickness resulted in maximum lap shear strength. Tool tilt did not show a significant effect on the sheet thinning.

Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic... more Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine

Materials Science and Technology, Jan 20, 2019

ABSTRACT The rate sensitivity of multiple obstacle aluminium alloy system was measured using the ... more ABSTRACT The rate sensitivity of multiple obstacle aluminium alloy system was measured using the stress relaxation method. A discrepancy was observed between the slope of the Haasen plot (rate sensitivity of dislocation–dislocation interaction) in pure metals and in alloys strengthened by multiple obstacles. Considering a simplifying assumption of the constant obstacle force–distance profile, it is suggested that slope of the Haasen plot is governed by glide dislocations’ length taking part in a thermally activated event. The relative strength and spacing of obstacles (forest dislocations, solutes and precipitates) is proposed to affect the thermally activated dislocation length, which in turn manifests as the difference in slope of the Haasen plot.

Materials Chemistry and Physics, Sep 1, 2018

In the present work, a criterion based on relation between strain hardening rate and rate of chan... more In the present work, a criterion based on relation between strain hardening rate and rate of change in activation volume is proposed for predicting formation of shear bands. The proposed criteria is validated by tracking changes in orientation distribution function (texture) as a function of shear band formation. The propensity of shear banding and its relation with operative rate controlling deformation mechanism is additionally discussed.

Metallurgical and Materials Transactions, Apr 26, 2018

Deformation behavior of an Al-Cu-Li alloy in different temper conditions (solutionized and T8) is... more Deformation behavior of an Al-Cu-Li alloy in different temper conditions (solutionized and T8) is investigated using stress relaxation tests. Fundamental parameters such as the apparent and physical activation volume, strain rate sensitivity, effective stress, and exhaustion rate of mobile dislocation density are determined from single and multiple relaxation tests. It was found that dislocation-dislocation interaction controls the kinetics of plastic deformation in the solutionized sample, whereas dislocation-precipitate interaction is the overriding factor in the presence of T 1 precipitates. The apparent activation volume was found to be significantly lower in the presence of T 1 precipitates compared with solutionized samples. Strain rate sensitivity and effective stress were found to be higher in the presence of T 1 precipitates. In addition, multiple relaxation tests showed that irrespective of microstructural features (solutes, semi-coherent precipitates), the mobile dislocation density reduces during the relaxation period. Further evidence regarding reduction in mobile dislocation density is obtained from uniaxial tensile tests carried out after stress relaxation tests, where both solutionized and T8 samples show an increase in strength. Additional discussion on relaxation strain is included to provide a complete overview regarding the time-dependent deformation behavior of the Al-Cu-Li alloy in different temper conditions.

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Jun 1, 2018

To reveal rate sensitive behavior of different obstacles observed in age hardenable aluminum allo... more To reveal rate sensitive behavior of different obstacles observed in age hardenable aluminum alloys, activation volume was measured as a function of flow stress. It was observed that solutes and precipitates are more rate sensitive compared to dislocations. Shearable precipitates were observed to be more rate sensitive amongst all obstacles.

Metallurgical and Materials Transactions, Jun 12, 2019

Materials Science and Technology, Aug 20, 2018

In the present work, a systematic investigation of crystallographic texture evolution and strain ... more In the present work, a systematic investigation of crystallographic texture evolution and strain hardening behaviour was undertaken to comprehend the deformation behaviour in the presence of T 1 (Al 2 CuLi) precipitates. Characteristic texture components symbolising multiple slip condition such as Copper and S were observed upon rolling which is in contrast with other Al alloys containing shearable precipitates. Strain hardening ability was also observed to be remarkably high in the presence of T 1 precipitates. The texture and strain hardening results are compared with another age hardenable Al alloy (Al-Mg-Si alloy) containing shearable precipitates to clearly bring out the difference in the nature of T 1 precipitates.

Metallurgical and Materials Transactions, Jan 29, 2020

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Jun 1, 2022

Social Science Research Network, 2022

Material flow and microstructure evolution are the two important aspects of the Friction stir wel... more Material flow and microstructure evolution are the two important aspects of the Friction stir welding (FSW) technique, which control the properties and performance of the friction stir welds. The present work investigates these two aspects of the FSW with main emphasis on the friction stir lap joints (FSLJs) on the AA6111 sheets. Due to the characteristic material flow during FSW, the faying surfaces in FSLPs are deposited in and around the weld nugget and create unavoidable defects. These defects reduce the load carrying thickness of the joints by providing an easy path for the weld failure. Therefore, to control the faying surface defects, a clear understanding of the material flow in FSW and its effect on the FSLJs is needed. With this objective, a comprehensive study of the material flow during FSLJs and the effects of various process parameters on the faying surface defects were conducted. This study not only revealed the mechanism of the formation of the faying surface defects but also explained the detailed material flow in the FSW. This investigation was further extended to study the role of FSW tool features on the material flow and the tool features to control the faying surface defects were proposed. The microstructure evolution during the FSW of AA6111 was investigated by differential scanning calorimetry (DSC), microhardness and transmission electron microscopy (TEM) techniques. This study showed that the increase in the heat input during FSW resulted in better aging response of the joints. The microhardness and strength variation across the FSW weld were explained from the DSC and TEM observations --Abstract, page iv

Social Science Research Network, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Materials Chemistry and Physics, May 1, 2019

Abstract In the present work, development of rolling texture in the presence of shearable precipi... more Abstract In the present work, development of rolling texture in the presence of shearable precipitates is analyzed using age hardenable aluminum magnesium silicon alloy (AA 6061) and aluminum-copper-lithium alloy (AA 2195). A characteristic Brass type texture evolves upon rolling of AA 6061 alloy containing β’’ (Mg5Si6) precipitates, whereas an unexpected Copper type texture develops upon rolling of AA 2195 alloy containing T1 (Al2CuLi) precipitates. The present work highlights that rolling texture evolution in the presence of shearable precipitates cannot be generalized and depends strongly upon the shearing propensity of these precipitates.

Modelling and Simulation in Materials Science and Engineering, Jun 14, 2018

Journal of Materials Engineering and Performance, Aug 19, 2021

Social Science Research Network, 2022