| Summary: | Technological developments especially in the field of construction and
manufacture is growing so fast and wide. This is due to the advances of
manufacturing process, especially technology of metal joints in particular metal
welding techniques. Continued development of welding technology researched
and developed to meet the needs of technical requirements and achieve a desirable
characteristic of joint. One type of welding technique is constantly being
developed is Friction Stir Welding (FSW). This study aimed to examine the effect
of T6 heat treatment on mechanical and fatigue properties of welded joints FSW
Al 6061 T6.
The materials used in the research were wrought aluminium alloy 6061 T6.
Materials were welded at 900 rpm rotation, feeding rate 30 mm/min and 2 ° slope
of tool. After the welding process, welded joints were conducted T6 heat
treatment process. Heat treatment process consisted of 2 parts: solution heat
treatment in which the welds were heated at a temperature of 550 ° and
subsequent cooling using water quenchant, followed by precipitation hardening
process at a temperature of 185 ° with a various of the holding time 2, 4 and 8
hours. A sequences of experiment were carried out including microstructure,
micro hardness, tensile strength, and fatigue crack propagation test.
Results of this investigation show that an increase in holding time leads to
coarse precipitates accompanied an increase in tensile strength and hardness.
However, fatigue crack growth rate (da/dN) of FSW joint tends to reduce
compared to unheat-treated FSW joint.
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