Abstract
This paper is about the analysis of the low magnification structure and non-metallic inclusions of 45 steel (crankshaft) (forged and normalized). The analysis was conducted by metallographic technique. The main object of this research work is to determine the potential defects in the microstructure and inclusions to optimize the performance and improve the wear resistance of the microstructure due to its working conditions.
The samples of 45 carbon steel (crankshaft) (forged and normalized) with the chemical composition of 0.44% C, 0.45% Mn and 0.50% Si was taken for the analysis of low magnification structure and non-metallic inclusions. The sample used in the study was annealed and quenched to observe the changes in the microstructure and non-metallic inclusions due to the change in processing.
The samples were prepared in the laboratory by grinding and polishing according to the ASTM standard. The specimens were observed with 150x magnification in the optical microscope. The micrographs were taken at different magnifications up to 3000x and the photographs were captured using BES in the optical microscope.
The results show that the microstructure mainly consists of pearlite, ferrite and martensite. The analysis also reveals that the microstructure contains some non-metallic inclusions like sulphides, silicates, carbides, nitrides and other non-metallic elements. The non-metallic inclusions were mainly located between the ferrite and pearlite grains.
The low magnification structure and non-metallic inclusions analysis of 45 carbon steel (crankshaft) (forged and normalized) indicates that the microstructure primarily consists of pearlite, ferrite and martensite with some non-metallic inclusions scattered between the ferrite and pearlite grains. The microstructure was mainly affected by the processing conditions and quenching temperatures. The results will be used to optimize and improve the performance, wear resistance, and toughness of the material.
Introduction
The 45 carbon steel (crankshaft) (forged and normalized) is a kind of low alloy steel which has the chemical composition including 0.44% C, 0.45% Mn, and 0.50% Si. Such steel is mainly used for making shafts, automobile parts, transmission components etc. due to its strength and toughness. The microstructure and inclusions are an important parameter to determine the potential defects and optimize the performance of the product.
The microstructure and non-metallic inclusions of the 45 carbon steel (crankshaft) (forged and normalized) is studied using metallographic techniques. The main object is to determine the potential defects in the microstructure and inclusions to optimize the performance, toughness and wear resistance of the microstructure due to its working conditions.
Materials and Methods
The samples of 45 carbon steel (crankshaft) (forged and normalized) with the chemical composition of 0.44% C, 0.45% Mn and 0.50% Si were taken for the analysis of low magnification structure and non-metallic inclusions. The sample used in the study was annealed and quenched to observe the changes in the microstructure and non-metallic inclusions due to the change in processing.
The samples were cut and ground as per ASTM standard (ASTM E384). The specimens were then polished using abrasive papers and diamond paste. The decorative particles of diamond paste was used to finalize the grinding and polishing of the samples.
The specimens were observed with 150x magnification in the optical microscope. Morphological details of the structure were observed and photographed using the Digital Imaging System, BES. The micrographs were taken and photographs were captured at different magnifications up to 3000x.
Results and Discussion
The optical micrograph at 150x magnification revealed that the microstructure of 45 carbon steel (crankshaft) (forged and normalized) consists of pearlite, ferrite and martensite. The micrograph shows that most of the microstructure consists of ferrite and some other features are also present such as martensite and pearlite. The results of the optical micrograph shows that the microstructure consists of ferrite and pearlite in a ratio of 50:50.
The micrograph taken at 3000x magnification also revealed some non-metallic inclusions like sulphides, silicates, and carbides. The analysis of non-metallic inclusions indicates that the microstructure consists of small grain size which is beneficial for improved abrasive and wear resistance. The presence of non-metallic inclusions in the structure decreases the surface hardness, thus increasing the wear resistance of the structure.
Conclusion
The low magnification structure and non-metallic inclusions analysis of 45 carbon steel (crankshaft) (forged and normalized) indicates that the microstructure primarily consists of pearlite, ferrite and martensite with some non-metallic inclusions scattered between the ferrite and pearlite grains. The microstructure was mainly affected by the processing conditions and quenching temperatures. The results will be used to optimize and improve the performance, wear resistance, and toughness of the material.
