scholarly journals Evaluation of Additive Friction Stir Deposition of AISI 316L For Repairing Surface Material Loss in AISI 4340

Author(s):  
Louis Peter Martin ◽  
Allen Luccitti ◽  
Mark Walluk

Abstract Additive technologies provide a means for repair of various failure modes associated with material degradation occurring during use in aggressive environments. Possible repair strategies for AISI 4340 steel using AISI 316L deposited by additive friction stir deposition (AFSD) were evaluated under this research by metallography, microhardness, and wear and mechanical testing. Two repair geometries were investigated: groove-filling and surface cladding. The former represents repair of localized grinding to eliminate cracks, while the latter represents material replacement over a larger area, for example to repair general corrosion or wear. The 316L deposited by AFSD exhibited a refined microstructure with decreased grain size and plastic strain, lower strength, and lower hardness than the as-received feedstock. Wear testing by both two-body abrasion and erosion by particle impingement indicated that the wear resistance of the 316L cladding was as good as, or better than, the substrate 4340 material; however, there was some evidence that the resistance to intergranular corrosion was compromised due to the formation of carbides or sigma phase. In both repair geometries, the microstructure of the substrate beneath the deposited material exhibited heat affected zones that appeared to have austenized during the deposition process, and transformed to martensite or bainite during cooling. This report constitutes an initial evaluation of a novel approach to the repair of structural steel components damaged by microcracking, wear or corrosion.

2011 ◽  
Vol 528 (6) ◽  
pp. 3003-3006 ◽  
Author(s):  
Mohsen Barmouz ◽  
Javad Seyfi ◽  
Mohammad Kazem Besharati Givi ◽  
Iman Hejazi ◽  
Seyed Mohammad Davachi

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
A. R. Sufizadeh ◽  
S. A. A. Akbari Mousavi

Dissimilar electron beam welding of 316L austenitic stainless steel and AISI 4340 low alloy high strength steel has been studied. Studies are focused on effect of beam current on weld geometry, optical and scanning electron microscopy, X-ray diffraction of the weld microstructures, and heat affected zone. The results showed that the increase of beam current led to increasing depths and widths of the welds. The optimum beam current was 2.8 mA which shows full penetration with minimum width. The cooling rates were calculated for optimum sample by measuring secondary dendrite arm space and the results show that high cooling rates lead to austenitic microstructure. Moreover, the metallography result shows the columnar and equiaxed austenitic microstructures in weld zone. A comparison of HAZ widths depicts the wider HAZ in the 316L side. The tensile tests results showed that the optimum sample fractured from base metal in AISI 316L side with the UTS values is much greater than the other samples. Moreover, the fractography study presents the weld cross sections with dimples resembling ductile fracture. The hardness results showed that the increase of the beam current led to the formation of a wide softening zone as HAZ in AISI 4340 side.


Author(s):  
Zhe Gao ◽  
Haris Khan ◽  
Jingjing Li ◽  
Weihong Guo

Abstract This research focused on developing a hybrid quality monitoring model through combining the data driven and key engineering parameters to predict the friction stir blind riveting (FSBR) joint quality. The hybrid model was formulated through utilizing the in-situ processing and joint property data. The in-situ data involved sensor fusion (force and torque signals) and key processing parameters (spindle speed, feed rate and stacking sequence) for data-driven modeling. The quality of the FSBR joints was defined by the tensile strength. Further, the joint cross-sectional analysis and failure modes in lap-shear tests were employed to confirm the efficacy of the proposed model and development of the process-structure-property relationship.


CORROSION ◽  
10.5006/2755 ◽  
2018 ◽  
Vol 74 (11) ◽  
pp. 1259-1271 ◽  
Author(s):  
Jalal Kangazian ◽  
Morteza Shamanian ◽  
Ali Ashrafi

Surface features of a dissimilar friction stir weld between Incoloy 825 Ni-based alloy and SAF 2507 super duplex stainless steel were investigated using scanning electron microscopy, microhardness test, cyclic potentiodynamic polarization, and electrochemical impedance spectroscopy. The surface of the weldment showed lower general corrosion resistance in comparison to the base metals. Areas under the weld shoulder exhibited weak pitting resistance because of the deformed structure and/or chromium nitride precipitates. Incoloy 825 located under the shoulder also displayed the highest susceptibility to pit growth because of the austenite matrix containing titanium nitride phases. Overall, the obtained results demonstrated that the friction stir welding method could significantly deteriorate the surface corrosion behavior of the processed regions.


Author(s):  
Debtanay Das ◽  
Swarup Bag ◽  
Sukhomay Pal ◽  
M. Ruhul Amin

Abstract Friction stir welding (FSW) is widely recognized green manufacturing process capable of producing good quality welded joints at temperature lower than the melting point. However, most of the works is focused on to the establishment of the process parameters for a defect-free joint. There is a lack to understand the formation of defects from physical basis and visualization of the same, which is otherwise difficult to predict by means of simple experiments. The conventional models do not predict chip formation and surface morphology by accounting the material loss during the process. Hence, a 3D finite element based thermo-mechanical model is developed following Coupled Eulerian-Lagrangian (CEL) approach to understand surface morphology by triggering material flow associated with tool-material interaction. In the present quasi-static analysis, the mass scaling factor is explored to make the model computationally feasible by varying the FSW parameter of plunge depth. The simulated results are validated with experimentally measured temperature and surface morphology. In CEL approach, the material flow out of the workpiece enables the visualization of the chip formation, whereas small deformation predict the surface quality of the joint.


Author(s):  
Amirreza Shahani ◽  
Ali Farrahi

The effect of five different stirring times of friction stir spot welding on lap-shear specimens of Al 6061-T6 alloy has been experimentally analyzed. The welding condition with 2 s of stirring shows the optimum mechanical behavior in comparison to the others. The static strength and fatigue behavior of the joint are justified using the microhardness profiles. The static results prove that the increase of stirring time beyond the 2 s case has little effect on improving the static strength. The fatigue results reveal two different failure modes, which are shear fracture at high load levels and transverse crack growth at low load levels. At medium load levels, although the final failure is similar to high load levels, the transverse growth of the crack outside the welding zone, just like low load levels, is also observed.


Author(s):  
Raul B. Rebak ◽  
Xiaoyuan Lou

Abstract Making light water reactor (LWR) components using additive manufacturing (AM) provides a high degree of design freedom to create complex near net shape geometries, with significant reduction in the deployment time. Since most of the current AM research focus on the refining of the fabrication variables, little information exists on the actual corrosion behavior (including general corrosion, localized corrosion and environmentally assisted cracking - EAC) of AM components. The most frequent operational material failure modes in LWR is EAC and debris fretting of fuel rods, therefore the objective of this work was to evaluate the environmental performance of AM type 316L SS in relation to the traditionally melted and forged wrought material. Stress corrosion cracking results show similar behavior between AM and wrought 316L SS in high temperature water. Ambient temperature electrochemical testing showed that the AM 316L SS was slightly more resistant to localized corrosion than the traditional wrought material and that AM material did not suffer sensitization during fabrication or heat treatment processes.


Author(s):  
G Girish ◽  
V Anandakrishnan

In this work, the dry sliding wear behaviour of recursively friction stir processed AA7075 was investigated using a pin-on-disc wear testing apparatus. The microstructure of the processed specimen was probed using optical microscopy, transmission electron microscopy and atomic force microscopy. Experiments were conducted using Taguchi experimental design by varying three different parameters like load, sliding velocity and sliding distance, and the analysis of variance was performed to identify the influence of the parameters over the wear rate. From the main effect plot, the combination of 9.81 N of load, 2 m/s of sliding velocity and a sliding distance of 2000 m was identified as the optimum levels that minimize the wear rate. The regression model was developed to calculate the wear rate, and the validation test was performed with the optimum parameter combination and compared with the experimental results. Wear tracks were examined using field-emission scanning electron microscopy to identify the type of wear mechanism.


2018 ◽  
Vol 6 (3) ◽  
pp. 036528 ◽  
Author(s):  
M Azizieh ◽  
M A G Dezfuli ◽  
Z Balak ◽  
H S Kim

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