Diffusion kinetics of borided AISI 52100 and AISI 440C steels

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• 作者：Yusuf Kayali^a ; ^{ykayali@aku.edu.tr} ; 陌brahim G&uuml ; ne艧^a ; Sinan Ulu^b
• 关键词：Boride layer ; Micro-hardness ; Diffusion kinetics ; Activation energy
• 刊名：Vacuum
• 出版年：2012
• 期刊代码：83_0042207x
• 类别：ph
• 出版时间：27 April, 2012
• 卷：86
• 期：10
• 页码：1428-1434
• 文件大小：2221 K

摘要

In this study, the case properties and diffusion kinetics of AISI 440C and AISI 52100 steels borided in Ekabor-II powder were investigated by conducting a series of experiments at temperatures of 1123, 1173 and 1223聽K for 2, 4 and 8聽h.The boride layer was characterized by optical microscopy, X-ray diffraction technique and micro-Vickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe₂B and CrB compounds.

The thickness of boride layer increases by increasing boriding time and temperature for all steels. The hardness of the boride compounds formed on the surface of steels AISI 52100 and AISI 440C ranged from 1530 to 2170聽HV_0.05 and 1620 to 1989聽HV_0.05, respectively whereas Vickers hardness values of untreated steels AISI 440C and AISI 52100 were 400聽HV_0.05 and 311聽HV_0.05, respectively. The activation energies (m>Qm>) of borided steels were 340.426聽kJ/mol for AISI 440C and 269.638聽kJ/mol for AISI 52100. The growth kinetics of the boride layers forming on the AISI 440C and AISI 52100 steels and thickness of boride layers were also investigated.