Post-heat treatment of electrochemically carburized low-carbon steel

Journal of Electrochemical Science and Engineering

article

Chan On Sow¹  Wong Min Jin Karen¹  Saffuan Awg Bahrin²  Bih Lii Chua¹  Gan Jet Hong Melvin³  Nancy Julius Siambun³ 

[1] Faculty of Engineering, Universiti Malaysia Sabah;Mechanical Engineering Department;Centre of Research in Energy and Advanced Materials, Faculty of Engineering, Universiti Malaysia Sabah

关键词: Steel;    electrochemical carburization;    molten salt;    quenching;    tempering;    annealing;   

DOI  :  10.5599/jese.1638

学科分类：内科医学

来源: International Association of Physical Chemists (IAPC)

【 摘 要 】

Limited studies are available on post-heat treatment (tempering/annealing) of electro­chemically carburized low-carbon steel, which can relieve internal stresses induced by the quenching process. In this study, the electrochemical carburization was carried out using the electrolyte mixture of sodium carbonate (Na2CO3) and sodium chloride (NaCl) under a CO2 gas environment and 800 °C. The samples were then quenched in either water or oil. The peak hardness of the water-quenched sample (WQ) was higher than the oil-quenched sample (OQ). Comparatively, post-heat treated (tempered and annealed) samples showed lower peak hardness compared to quenched samples. An optical microscope was used to observe microstructural changes, while X-ray diffraction (XRD) was used to examine metal phases within all samples. The full width at half maximum (FWHM) of the martensite peak supported the stress relief in both tempered and annealed samples. Scanning electron microscope (SEM) with energy dispersive X-ray (EDX) was applied to determine the elemental composition of as received and electrochemically carburized and quenched low-carbon steel samples. The carbon content of the WQ sample was relatively higher than the OQ sample, whereas the tempered samples showed higher carbon content compared to the annealed samples, but both were lower than for quenched samples. Electrochemical carburization increased the carbon content and improved the hardness, while the tempering or annealing process relieved internal stresses that resulted in the hardness reduction.

【 授权许可】

CC BY