Issue 78

N. Mohan et alii, Frattura ed Integrità Strutturale, 78 (2026) 129-145; DOI: 10.3221/IGF-ESIS.78.08

AISI 316L steel via powder-pack boriding. Tribocorrosion tests conducted in Hank’s solution using a ball-on-flat setup and a three-electrode cell, with material loss estimated as per ASTM G119, showed a 1.5-fold improvement in tribocorrosion resistance compared to untreated steel, attributed to wear–corrosion interactions [11]. Aichholz et al. examined boronized AISI 4140 steel and reported the formation of a single-phase Fe ₂ B layer, which resulted in significantly lower wear rates and coefficients of friction under tribocorrosion conditions, although the trend reversed in dry sliding [12]. García-León et al. studied borided AISI 316L steel in Hank’s solution and observed a threefold reduction in wear rate compared to non-borided steel under wet sliding conditions. XPS analysis indicated the formation of a passive layer containing B ₂ S ₃ , Cr ₂ O ₃ , and Fe ₂ O ₃ , which reduced wear by minimizing mechanical contact and promoting tribofilms formation [13]. Furthermore, Arteaga-Hernandez et al. evaluated the effect of boriding on the tribological behavior of AISI 316L stainless steel, highlighting its potential to enhance material performance for biomedical applications [14]. Results indicated that all borided samples exhibited reduced wear rate compared to untreated samples, with specific parameters showing optimal performance. The boriding treatment also enhanced corrosion resistance by acting as a barrier against pitting corrosion. From the above literature, it can be observed that boronizing can significantly improve the tribocorrosion resistance of stainless steels. However, it is important to note that electrochemical media plays a significant role. It is seen that when NaCl is used as the electrochemical media, less corrosion resistance is observed as compared to the increased corrosion resistance observed in biological solutions. Also, the studies focus on boronized austenitic grades of stainless steels while no research on the tribocorrosion behavior of boronized 13Cr4Ni and 16Cr5Ni MSS is reported. These materials, with their unique compositions and additional surface treatment, offer potential for even greater improvements in tribocorrosion resistance. This research aims to fill the gap by studying the effects of boronizing on 13Cr4Ni and 16Cr5Ni martensite stainless steels, focusing on their tribocorrosion behavior in NaCl media. The study involves separate corrosion tests, wear tests, and combined tribocorrosion tests to comprehensively understand the interactions between mechanical wear and chemical corrosion. By comparing the results of tribocorrosion tests with wear and corrosion tests individually, the influence of corrosion and wear can be elucidated, providing valuable insights into material performance. Potentiodynamic polarization tests in both static and dynamic conditions, dry sliding wear tests in both the presence and absence of electrochemical media were performed. Optical profilometer, SEM and EDS techniques were used to quantify the wear rate and understand the wear mechanism.

E XPERIMENTAL PROCEDURE

Materials and methods HEL in Haridwar, India, provided the as-cast 13Cr4Ni and 16Cr5Ni SMSS materials. Wavelength-dispersive X ray fluorescence spectroscopy was used to evaluate their chemical makeup (Tab. 1). Samples with a diameter of 30 mm were made and polished with silica abrasive paper up to 2000 grit. After that, a mixture of silicon carbide (90 wt. %), potassium tetrafluoroborate (5 wt. %), and boron carbide (5 wt. %) was used for pack boronizing at 950°C and 1000°C for six hours. This was followed by two hours of tempering at 600°C. B

Elements

C

Si

Mn

P

S

Cr

Ni

Cu

Mo

Fe

13Cr4Ni SMSS

0.022

0.83

0.98

0.006

0.002

13.1

3.7

0.56

0.59

Balance

16Cr5Ni SMSS

0.022

1.44

1.04

0.007

0.002

15.7

4.6

0.49

0.98

Balance

Table 1: Chemical composition (in wt %) of 13Cr4Ni and 16Cr5Ni SMSS.

Corrosion test Boronized samples were subject to potentiodynamic polarization tests in the tribocorrosion setup instead of standard electrochemical cell, connected to Gamry 1000 potentiostat. The test setup is as shown in Fig. 1. The tests were carried out in 0.6 M NaCl solution at ambient temperature. SCE, graphite rod and boronized steel sample were used as reference, counter and the working electrode respectively. Potentiodynamic polarization tests were conducted after an initial delay of 900 s using a scan rate of 1mV/s (both forward and backward). The tribometer was not switched on for the entire duration of the test.

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