Abstract

In this research work, low-temperature carburizing of AISI 420 martensitic stainless steel was conducted at 460 °C for different amounts of time using an acetone source. The microstructure and phase structure of the carburized layers were characterized by optical microscope and X-ray diffraction. The properties of the carburized layers were tested with a microhardness tester and an electrochemical workstation. The results indicate uniform layers are formed on martensitic stainless steel surfaces, and the carburized layers are mainly composed of carbon “expanded” α (αC) and Fe3C phases. The property tests indicated that after plasma–carburizing, the hardness of the stainless steel surface can reach up to 850 HV0.1. However, the corrosion resistance of stainless steel decreased slightly, and the corrosion characteristic of stainless steel was altered from pitting to general corrosion. The semiconductor characteristic of the passivation film on stainless steel was transformed from the p-type for untreated specimens to the n-type for carburized specimens.

Highlights

  • Stainless steel is widely used for its inherent corrosion resistance

  • There are various surface modification methods that have been utilized to improve the properties of stainless steel, of which thermo-chemical diffusion treatment strategies have drawn significant consideration for their simple process, low cost, and other advantages [5]

  • Since the corrosion resistance of the carburized layer is one of the important concerns for stainless steel, the present investigation primarily focused on the corrosion behaviors of the carburized layer

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Summary

Introduction

Stainless steel is widely used for its inherent corrosion resistance. unmodified stainless steel can be problematic when it is used in moving parts in some harsh environments, such as aerospace, electric power stations, ships, and ocean engineering [1]. Low-temperature nitriding, carburizing, and nitrocarburizing treatments are the commonly used processes that can improve the hardness and wear–resistance of stainless steels without reducing their corrosion resistance [6,7]. These treatments have received extensive research attention [7,8,9]. Regarding the low-temperature carburization of stainless steel, most research is focused on studying the microstructure and mechanical properties of the modified layers [10,11,12,13,14]. Since the corrosion resistance of the carburized layer is one of the important concerns for stainless steel, the present investigation primarily focused on the corrosion behaviors of the carburized layer

Materials and Experimental Methods
Phase Structure of the Carburized Layer
Microstructure and Hardness
Corrosion Behavior of the Carburized Layer
Nyquist
Conclusions

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