Influence of tempering conditions on the microstructure and mechanical properties of nodular cast iron

ABSTRACT

In the present work, nodular cast iron (NCI) was austenitised at 1173 K (900°C) for 2 h followed by quenching and subsequently tempered at a temperature ranged from 523 K (250°C) to 923 K (650°C) in 100 K (100°C) increments for 1 h, 1.5 h and 2 h, respectively, to investigate the microstructure and mechanical properties of the material. These heat treatments control the rate of austenite to pearlite transformation and the size of second-phase particles that greatly influenced the mechanical properties of the material. The study of tensile properties reveals that with varying tempering temperature from 523 K (250°C) to 923 K (650°C), ultimate tensile strength (UTS) value initially increases, reaches to maximum and then decreases. At particular tempering temperature with increase in tempering time, the UTS, hardness and impact strength decrease. The optimum mechanical properties (UTS~1040 MPa, El~2%, Impact Toughness~9 J) were obtained at the tempering temperature of 723 K (450°C) with the tempering time of 1.5 h. Fractured surfaces observed using a scanning electron microscopy indicate the significant influence of different tempering conditions on the mode of the failure of NCI.

KEYWORDS:

• Tempering
• cast iron
• casting
• heat treatment
• mechanical properties
• failure analysis

Acknowledgments

The authors would like to express their most sincere gratitude and appreciation to Mr. Balwinder Singh, G.S. Auto International Ltd. Ludhiana, who has taken great pleasure in conducting experiments at various stages.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data sharing is not applicable to this article as no new data were created or analysed in this study.

Additional information

Notes on contributors

Avtar Singh

Dr. Avtar Singh completed his Ph.D. on the topic of “Chemo-mechanical modeling of fracture in heterogeneous cathode for lithium-ion batteries” from the Indian Institute of Technology Roorkee. He completed his Master's from Motilal Nehru National Institute of Technology on ”Effect of ferritization on the microstructure and mechanical properties of nodular cast iron”. His research areas are Multiphysics, Mechanics of Materials, Fracture Mechanics, Phase transformation, and Material Characterization.

Mayank Agarwal

Dr. Mayank Agarwal is Associate Professor of Mechanical Engineering at Institute of Engineering and Technology Dr. RML Avadh University Ayodhya, India. He completed his Ph.D. from Motilal Nehru National Institute of Technolgy Allahabad. His research contributions are in the field of Semi-solid Casting, Material Characterization and Bio-composite. He is currently working on powder metallurgy and coating & cladding process.