The Effect of Nitriding and Oxidation Treatment On the Resistance of Steel to Erosion in Liquid Aluminum
Date Issued
2009
Date
2009
Author(s)
Lee, Chien-Wei
Abstract
Tool steels, such as SKD61, SKH51, SKD11 and SUS420J2, after nitriding, oxidation, or nitride-oxidation compound treatment are dipped in liquid aluminum at 720℃ for erosion tests. Effects of above surface modification treatments on the resistance of steels to erosion in liquid aluminum are evaluated by weight loss per unit surface area. Furthermore, erosion mechanism of steels in liquid aluminum is investigated through microstructure observation, chemical composition analysis and X-ray diffraction test. The experimental results show that the resistance of steels to erosion in liquid aluminum can be significantly increased either by nitriding or oxidation treatment. Moreover, the effect of resisting erosion for nitride-oxidation compound treatment in especially excellent. The weight loss of steel sample after the compound treatment is smaller than one tenth of the plain steel at the same erosion test conditions. The dominant process of erosion mechanism in that the iron atom of steels diffuses to liquid aluminum and formed Fe-Al-Si intermetallic compounds with the element of aluminum and silicon in the liquid. Either the nitrided layer or oxidation layer of steels is a barrier for iron atom to diffuse to liquid aluminum that results in the reduction of erosion rate of steels.
Subjects
Tool steel
Nitriding
Oxidation
Erosion
Fe-Al-Si inermetallic compound
Type
thesis
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