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2 Archives of Metallurgy and Materials

2 2019

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Friction and Wear Behavior of Direct Metal Deposition on SUH3

Choi Byungjoo, Cho In-Sik, Jung Do-Hyun, Lee Moon G., Jeon Yongho

Archives of Metallurgy and Materials

2019

Vol. 64, iss. 3

841--844

Poppet valves made from high-frequency heat-treated SUH3 steel have insufficient durability, and scratches appear on the valve face in prolonged use. It is necessary to develop surface treatment technology with excellent durability to prevent the deterioration of engine performance. Therefore, a surface treatment technology with higher abrasion resistance than existing processes was developed by direct metal deposition to the face where the cylinder and valve are closed. In this study, heat pretreatment and deposition tests were performed on three materials to find suitable powders. In the performance evaluation, the hardness, friction coefficient, and wear rate were measured. Direct metal deposition using Inconel 738 and Stellite 6 powders without heat pretreatment were experimentally verified to have excellent durability.

Analysis and Verification of Physical Properties of an AISI 4140 Steel by Vickers Indentation Analysis According to the Presence of Residual Stresses

Jung Changho, Lee Moon G., Jeon Yongho

Archives of Metallurgy and Materials

2019

Vol. 64, iss. 3

823--827

Residual stress has a great influence on the metal, but it is difficult to measure at small area using a general method. Residual stress calculations using the Vickers indentation can solve this problem. In this paper, a numerical simulation has been made for the residual stress measurement method of metal material deformed by high-speed impact. Then, the stress-strain curve at the high-speed deformation was confirmed through actual experiments, and the residual stresses generated thereafter were calculated by the Vickers indenter method. A Vickers indentation analysis under the same conditions was performed at the position where a residual stress of about 169.39 MPa was generated. Experiments were carried out and high speed impact was applied to the specimen to generate residual stress. The obtained results indicate that it is possible to identify residual stresses in various metals with various shapes through Vickers indentation measurements, and to use them for process and quality control.