Effect of the Atmosphere for Heat Treatment on Carbon Flux in Ultra-Rapid Carburizing

Yamamoto, Ryosuke; Nishimoto, Akio; Toda, Kazutoshi

doi:10.2320/matertrans.mt-h2022001

Cited by 4 publications

(1 citation statement)

References 27 publications

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“…Gas carburizing is mostly used in the heat treatment industry because the carburizing reaction occurs in an equilibrium state, and precise carbon potential control is possible [1,2]. The carburizing source used in gas carburizing uses methane and propane as saturated hydrocarbons, and since it takes a long time to reach the equilibrium phase, soot is easily formed [3][4][5]. On the other hand, the vacuum carburizing process uses acetylene, an unsaturated hydrocarbon, in a low-pressure (1-10 Torr) atmosphere to rapidly decompose iron as a catalyst, causing a fast carburizing reaction in a non-equilibrium state.…”

Section: Introductionmentioning

confidence: 99%

Influence of Alloying Elements on the Carburizing Behavior in Acetylene Atmosphere

Kwon,

Park,

Lee

et al. 2023

Metals

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Three steel types (AISI 1020, AISI 8620, AISI 4120) with similar carbon content and different Cr content were used as test specimens to closely examine the effect of alloying elements for carbon penetration and diffusion on the steel surface during vacuum carburizing. The carbon mass gain according to the carburizing time was measured using a microbalance, and the average carbon flux, which is an indicator of the carbon penetration rate, was calculated using the measured weight as a variable. The outermost surface of the carburized specimen was observed by scanning electron microscopy (SEM) and Raman spectroscopy (RS), and the reason for the change in carburization rate according to the steel type was identified in relation to the equilibrium carbon contents calculated from Thermo-Calc. The overall carbon distribution and distribution of alloy elements on the outermost surface were quantitatively analyzed using an electron probe microanalyzer (EPMA). On the surfaces of the AISI 1020 and AISI 4120 carburized specimens, graphite layers and grain boundary carbide were formed during the carburizing process, which hindered the carburization rate, while no abnormal layer was observed on the surface of the AISI 8620 carburized specimens, so the overall carburization results were excellent.

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