Low-temperature plasma carburizing of AISI 420 martensitic stainless steel: Influence of gas mixture and gas flow rate

► Carbides and expanded martensite are the main phases on the modified surface. ► Gas mixture composition significantly influences low temperature plasma carburizing. ► Equal or more than 1% CH4 contents in the gas mixture lead to soot formation. ► The total gas flow rate has minor influence on low temperature plasma carburizing. ► Optical emission spectroscopy cannot be applied to control the process.