Modeling of thermal cycles and microstructural analysis of pipeline steels processed by friction stir processing

Abstract Friction stir processing was used to prepare aluminium metal matrix composite reinforced with B4C particles. The micro-hardness of the composite was improved by selecting the process parameters. Friction stir processing parameters, namely tool rotational speed, tool tilt angle and different pin profiles, were explored by using Taguchi’s L9 orthogonal array and analysis of variance. Optical microscopy and scanning electron microscopy were employed for microstructural analysis. X-ray diffraction was used to evaluate the residual stress. Experimental results illustrated that increased rotational speed, reduced tilt angle and square pin profile of the tool gave more uniform dispersal of B4C content with maximum micro-hardness. Small amounts of compressive residual stress developed at the stirred and thermo-mechanically affected zones confirmed the adequate improvement in micro-hardness. Micro-hardness of fabricated Al 6063/B4C composite surfaces was enhanced by 30% as compared to Al 6063 alloy.

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The Influence of Multiple Pass Submerged Friction Stir Processing on the Microstructure and Mechanical Properties of the FSWed AA6082-AA8011 Joints

Metals ◽

10.3390/met10111429 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1429

Author(s):

Sipokazi Mabuwa ◽

Velaphi Msomi

Keyword(s):

Mechanical Properties ◽

Friction Stir Processing ◽

Microstructural Analysis ◽

Base Material ◽

Tensile Tests ◽

Friction Stir ◽

Grain Sizes ◽

Microstructure And Mechanical Properties ◽

Multiple Pass ◽

The One

The AA6082–AA8011 friction stir-welded joints were subjected to submerged multiple pass friction stir processing to evaluate the microstructure and mechanical properties of the joints. A maximum of four submerged friction stir processed passes were used in this study. All the specimens were extracted from three different joint positions (start, middle and end). The tests conducted included microstructural analysis, tensile tests, hardness and fracture surface morphology of the post-tensile specimens, were performed using a scanning electron microscope (SEM). There was no particular trend in the microstructure and mechanical properties when looking at the specimen positioning in all the passes. The minimum mean grain sizes were refined from 3.54 to 1.49 µm and the standard deviation from 5.43 to 1.87 µm. The ultimate tensile strength was improved from 84.96 to 94.77 MPa. The four-pass SFSPed specimens were found to have more ductile properties compared to the one-pass SFSPed one. The hardness of the stir zones in all the passes was found to be higher compared to the AA8011 base material but lower than the AA6082 one. The maximum stir zone hardness of 75 HV was observed on the one-pass SFSP joints.

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The effect of material position of multi-pass friction stir processing on friction stir welded AA1050/AA6082 dissimilar joints

E3S Web of Conferences ◽

10.1051/e3sconf/202130901001 ◽

2021 ◽

Vol 309 ◽

pp. 01001

Author(s):

Oritonda Muribwathoho ◽

Velaphi Msomi ◽

Ali Merdji ◽

Sipokazi Mabuwa

Keyword(s):

Grain Size ◽

Tensile Strength ◽

Friction Stir Welding ◽

Friction Stir Processing ◽

Vickers Microhardness ◽

Microstructural Analysis ◽

Dissimilar Joint ◽

Dissimilar Joints ◽

Friction Stir ◽

Number Of Passes

The AA1050 and AA6082 plates were used in producing dissimilar joint through friction stir welding (FSW) technique. The developed dissimilar joint was then subjected to multi-pass friction stir processing (FSP) technique. Various tests for the AA1050/AA6082 (AA1050 on the advancing side) and AA6082/AA1050 (AA6082 on the advancing side) joints were conducted on joints subjected to 1pass (1P) and 4pass (4P). The microstructural analysis showed that the increase in number of FSP passes resulted in a reduced grain size regardless of the of material position. The Vickers microhardness for AA1050/AA6082 FSPed joints increased towards AA6082 side while the microhardness for AA6082/AA1050 FSPed joints decreased towards the AA 1050 side regardless the number of the passes. The ultimate tensile strength (UTS) of AA1050/AA6082 joint increased with an increase in the number of passes while AA6082/AA1050 fluctuated between the specimens sampled from different locations of the FSPed joints.

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