Effect of welding heat input on the microstructure and mechanical properties of abs grade a steel at coarse grain heat affected zone (CGHAZ)
The fabrication and construction of structures used in the offshore and marine industries shall be made according to the international code and standard requirements to ensure the quality and to extend the life span. Proper material selection needs to be carried out to achieve proper function and to...
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| Format: | Thesis |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/7499/ http://eprints.uthm.edu.my/7499/1/wan_shaiful_hasrizam_wan_muda.pdf |
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| Summary: | The fabrication and construction of structures used in the offshore and marine industries
shall be made according to the international code and standard requirements to ensure
the quality and to extend the life span. Proper material selection needs to be carried out
to achieve proper function and to reduce the cost. The ABS Grade A steel is one of the
huge materials used in the marine industries. The study has been carried out to scrutinize
the effect of welding heat input to the distribution of microstructure formation and its
mechanical properties at CGHAZ of the ABS Grade A steel. Three heat input
combinations designated as low heat (0.99 kJ/rnm), medium heat (1.22 Wrnrn) and high
heat (2.25 kJ/mm) have been used to the weld specimen by using flux cored arc welding
(FCAW) process. The microstructure formation at CGHAZ consists of grain boundary
ferrite (GBF), Widmanstatten ferrite (WF) and pearlite (P). Significant grain coarsening
was observed at the coarse grain heat affected zone (CGHAZ) of all the joints and it was
found that the extent of grain coarsening at CGHAZ increased with the increase in the
heat input. The results of the mechanical investigation indicate that the joints made
using low heat input exhibit higher hardness and impact toughness value than those
welded with medium and high heat input. It can be concluded that the higher the heat
input, the higher the grain size of microstructure but will lead to lower hardness and
impact toughness value. |
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