The present paper reports the experimental results onmartensitic stainless steel low-temperature plasma assisted
carburizing kinetics. The treatments were carried out using a gas mixture of 99.5% (80% H2+20% Ar)+0.5% CH4
at temperatures of 623, 673, 723 and 773 K and for times of 4, 8, 12 and 16 h. The peak voltage and the pulse period
of the pulsed DC power supply were kept constant at 700 V and 240 μs, respectively. Temperature was controlled
by adjusting the duty cycle. The treated samples were characterized by confocal laser scanning microscopy, X-ray
diffractometry and microhardness measurements. Results indicate that low-temperature plasma carburizing is a
diffusion controlled process. The calculated activation energy for outer and diffusion layer growth was 29 and
85 kJ mol
−1
, respectively. An apparently precipitation-free layer can be produced only when the processing tem-
perature is sufficiently low (≤723 K) and time sufficiently short (≤12 h).