Now showing 1 - 6 of 6
  • Publication
    Effect of FSW parameters on temperature profile and grain size of AA6061-T6 and S275JR mild steel FSW joint
    Friction stir welding (FSW) is a solid-state welding technique used to join materials such as aluminum alloy, magnesium alloy, steel and titanium. The process involves relatively low process temperatures compared to other conventional welding techniques. Welded material undergoes severe plastic deformation driven by the rotating FSW tool, which causes dynamic recrystallization of grains. In this study, the temperature during the welding of AA6061-T6 aluminum alloy and S275JR mild steel was recorded using K-type thermocouple. Grains in the stir zone (SZ) of joints were observed in order to measure the grain size. Samples were etched with Keller's reagent to reveal its microstructure. It was seen that the highest temperature was recorded when welding with a high tool plunge depth. Decreasing tool travel speed was seen to increase temperature readings. The lowest temperature was recorded when using a high tool tilt angle due to a reduced contact area between tool shoulder and weld piece. Largest observed grain size was measured in the SZ of the joint welded with a high tool plunge depth, due to the high process temperature experienced by the joint during welding.
  • Publication
    Influence of dissimilar plate thickness on temperature during friction stir welding between aluminium alloy and steel
    ( 2024-03-07) ;
    Afendi M.
    ;
    Syafiqah W.N.
    Joining aluminium alloy and steel together is hard due to different thermomechanical properties of two materials. FSW was introduced to join two different materials in a safer way. The observation of influence of plate thickness difference between AA6061-T6 aluminium alloy and S235JR mild steel plates, plate positioning and plunge depth during FSW on temperature profile has been conducted to address the increasing interest in FSW to join dissimilar plate thicknesses in applications such as tailor welded blanks. Varying plate thickness, plate position and plunge depth from the top of the thickest plate will be used as the study parameters. By using eleven (11) welded samples with different parameters as guide, the experiment was conducted by using conventional milling machine with specialised tool for FSW. Temperature profile results were expressed in line graphs. As in conclusion, higher plate thickness ratio which is obtained when thicker plate divided by thinner plate can lead to lower peak temperature result, thus first objective is achieved. The second objective achieved as results show that joints with backers tend to have higher peak temperature and the last objective achieved when results of deeper plunge depth gave higher peak temperature as the tool shoulder came in contact with thermocouple during the process.
  • Publication
    Influence of friction stir welding parameters on joint defects, temperature and hardness of AA6061-T6 and S27JR mild steel FSW joint
    The influence of welding parameters such as tool plunge depth, tool travel speed and tool tilt angle on welding temperature during friction stir welding of AA6061-T6 and S275JR mild steel was the focus of this research. Thermocouple placed in the aluminum alloy plate prior to welding was used to measure the temperature during the welding of joints under different set of parameter values. Joint appearance as well as defects occurring on the surface or within the joint was observed. Microhardness profiles were also taken by measuring microhardness values across the cross section of joints. Excessive flash, tunnel defects and insufficient welding were the type of weld defects observed on different joints with different parameters. Defects were attributed to the varied parameter values affecting the heat generation as well as the flow of the plasticized material. Highest temperature was recorded by the joint fabricated using the largest tool plunge depth, owing to the increased downwards pressure. Microhardness profiles were seen to be similar for all the welded joints. A “plateau” of low microhardness value was observed for all joints associated with the thermomechanically affected zone (TMAZ) and heat affected zone (HAZ). A wider plateau was observed for joints welded with higher tool plunge depth due to higher temperature.
  • Publication
    Effect of quenching on the mechanical properties of carbon steel for hammer mill
    ( 2021-10-25)
    Marthini V.
    ;
    Alhelali I.A.A.
    ;
    Afendi M.
    ;
    Majid M.
    ;
    This paper covers the effect of quenching on the mechanical properties of high carbon steel for hammer mill. The main objective of this study is to investigate the mechanical properties and microstructure of high carbon steel before and after heat treatment (i.e., quenching). In this study, the specimens were heated at different level temperature which are 750 °C,800 °C and 900 °C prior to quenching process in water with soaking time of 5 minutes. After the heat treatment of quenching process completed, Rockwell hardness test and tensile test were performed, and the results were collected for both untreated and heat-treated specimens. The fractured surfaces of the specimens were also examined by using metallurgical microscope. It was observed that different level of quenching temperature and untreated specimens gave different mechanical properties. The specimen undergone water quenching recorded the highest hardness and tensile strength as 67.9 HRA and 426.11 MPa, respectively. Besides, the microstructure obtained from untreated specimen provided a good combination of ferrite and pearlite, meanwhile in quenched specimens formation of martensite was observed.
  • Publication
    Parametric investigation for single sided and double sided friction stir welding of aluminium alloy 6061-t6 and s275jr mild steel butt joint
    Friction stir welding (FSW) is a solid-state joining technique capable of joining aluminum and steel together, which is beneficial to multiple industries such as the automotive, aerospace and chemical industry is attributed by the combined high strength and toughness of steel as well as the corrosion resistance and low density of aluminum alloys. However, joining these two materials together has proven to be a difficult undertaking due to a strong tendency to form large amounts of brittle and hard intermetallic compounds (IMC) at the interface as a result of mutual diffusion during welding. While the growth of IMC layer is minimized in FSW due to the low process temperature, investigation on the influence of welding parameters on IMC layer formation as well as other joint properties such as tensile strength and hardness is required. The appearance of FSW-related joint defects such as tunnel defects, insufficient welding and root defects are also of interest due to its negative effect on joint strength. The influence of double sided FSW (DS-FSW) on joint properties of aluminum-to-steel joints as well as its ability to fix root defects also require evaluation. Several welding parameters were studied and their effects on joint properties investigated: tool offset, tool rotation direction, tool plunge depth, tool travel speed and tool tilt angle. Joints were evaluated based on their microstructural characterizations such as weld zones, IMC layer thickness, grain size in the stir zone and properties such as hardness and tensile strength. Defects formed on the joint such as excessive material flash, insufficient bonding, tunnel defect and root defect were scrutinized. The thickness of IMC layer at the top and middle region of the joint were measured for all joints. Tool plunge depth was seen to substantially influence heat generation and downwards pressure, evidenced by the appearance of tunnel defects at 0.1 mm and thick IMC layers at 0.3 mm and 0.5 mm tool plunge depth. At very low (30 mm/min) and very high (110 mm/min) tool travel speed, tunnel defects were formed. At 1° low tool tilt angle, welding was successfully performed. IMC layer formed in the joint was thinner than ones in a joint produced at 3° tool tilt angle, however at the topmost region of the joint it was thicker. Root defect was observed in all the welded joints. Removing the root defect from tensile specimens of several joints by machining was found to substantially increase the joint strength as fractures no longer initiate at the root defect. However, several joints without root defect still fractured at the interface, which was determined to be caused by thick IMC layer at the crown. Double sided FSW (DS-FSW) was investigated as a possible method to eliminate root defects without material removal by machining. It was found that using DS-FSW with a 4.5 mm and 4.0 mm tool pin length was successful in removing the root defect, however joints still fractured at the interface. It was found that thick IMC layers were formed at the 1st side crown of the joint. By performing DS-FSW using shorter tool pins of 3.5 mm and 3.0 mm, root defects were successfully removed and the joint fractured away from the interface, signifying satisfactory bonding. The IMC layer thickness along the depth of joints were measured to investigate DS-FSW’s effects. It was observed that longer tool pins resulted in thicker IMC layer and vice versa.
  • Publication
    Influence of dissimilar plate thickness on temperature during friction stir welding between AA5083 and AA6061 aluminium alloy grades
    This paper investigates the influence of dissimilar plate thickness on the temperature profile of AA5083 and AA6061 aluminium alloy. Plates of dissimilar aluminium alloy grades are welded in a butt joint configuration by using a milling machine and a custom FSW tool made of H13 tool. Datalogger and type K thermocouples embedded in the workpieces at different distances from the weld line are used to collect the temperature data during the experiment. One thermocouple is placed at each side of the advancing side and retreating side at equally distance from the center line except for Joint 1, 2 and 3. The results show the range of temperature measurement during the experiment is between 300°C and 600°C. FSW process between similar plate thickness produces the highest value of peak temperature and better surface appearance than dissimilar plate thickness. The thermocouples located near the weld line contributed the higher temperature since the heat source comes from the rotating tool. Besides, higher temperatures were recorded at 5 mm thickness of AA6061 aluminium alloy plate located on the advancing side than the retreating side.