Abstract

Mechanical properties of DP (Dual Phase) steels are greatly influenced by the microstructural features such as grain size, morphology and martensite volume fraction (V m %). These microstructural features can be altered by changing the soaking time and temperature within intercritical zone. Present study aims to study the effect of intercritical annealing temperature and soaking time on V m % and its effects on mechanical properties of plain low carbon steel grade (AISI 1020) steel having ferrite-martensitemicrostructure. Nine DP steel specimens with various amount of martensite were produced via intercritical heat treatment. Mechanical properties including TS (Tensile Strength), hardness and toughness were characterized and co-related with martensite volume fraction. It was found that increasing the intercritical annealing temperature and soaking time increases the V m %. The optimum TS and hardness were found at 64V m % and then decrease with further increase in V m %. The toughness was found to have linear relationship with V m %.

Highlights

  • DP steels are kind of advanced strength steel mostly used by automobile industry due to their special mechanical properties such as continuous yielding, high TS, high work hardening rate as well as good ductility [1-4]

  • The automotive industry is continuously exploring methods of enhancing their ductility and strength simultaneously to develop superior grades of such steels [2]. These properties are result of special microstructure designed to produce in DP steel which consists of soft matrix of ferrite in which islands of hard martensite are embedded [3,4]

  • Movahed et al [1] and Ebrahimian and Ghasemi, [10] have reported a linear variation of yield strength with martensite volume fraction characterize the microstructure- property relationship of micro alloyed low carbon DP steels, literature pertaining to formation of ferrite-martensite DP microstructure and its effect on mechanical properties of plain low carbon steels has not been well studied

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Summary

INTRODUCTION

DP steels are kind of advanced strength steel mostly used by automobile industry due to their special mechanical properties such as continuous yielding, high TS, high work hardening rate as well as good ductility [1-4]. The automotive industry is continuously exploring methods of enhancing their ductility and strength simultaneously to develop superior grades of such steels [2] These properties are result of special microstructure designed to produce in DP steel which consists of soft matrix of ferrite in which islands of hard martensite are embedded [3,4]. Movahed et al [1] and Ebrahimian and Ghasemi, [10] have reported a linear variation of yield strength with martensite volume fraction characterize the microstructure- property relationship of micro alloyed low carbon DP steels, literature pertaining to formation of ferrite-martensite DP microstructure and its effect on mechanical properties of plain low carbon steels has not been well studied. Aims to investigate the effect of intercritical annealing temperature and soaking time on martensite volume fraction and mechanical properties of AISI 1020 plain carbon steel.

Microstructure
Tensile Strength
Hardness
Toughness
CONCLUSION
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