MICROSTRUCTURE, MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF AISI 316L STAINLESS STEEL DURING SALT BATH NITRIDING

The aim of the current work was to analyse the impact of salt bath nitriding on the behavior of the tribological characteristics and surface microstructures of AISI 316L stainless steels. Nitriding was carried out at 580°C for 10 h. The tribological, structural behavior of the AISI 316L before and after salt bath nitriding was compared. The surface microstructures, tribological characteristics, as well as its surface hardness, were investigated using optical microscopy (OM), X-ray diffractometer (XRD), surface profilometer, pin-on-disk wear tester and microhardness tester. In the current work the experimental results showed that a great surface hardness could be achievable through salt bath nitriding technique because of the formation of the so-called expanded Austenite (S-phase), the nitrogen diffusion region. The surface hardness of AISI 316 stainless steel after nitriding process reached 1100 HV0.025 which was six times the untreated sample hardness. The S-phase is additionally expected to the improvement of wear resistance and decrease the friction coefficient.

Assessment of Wear Behavior on Treated AISI 630 Stainless Steel by Salt Bath Nitriding Process under Dry Sliding Conditions

Grade 630 martensitic precipitation hardening stainless steel has a combination of high hardness and strength after suitable heat treatment. The great advantage of this grade is that they are usually supplied in the condition treated with the solution and then aged to achieve a sufficient high strength. Chosen for this research work, AISI 630 stainless steel samples were subjected to salt bath nitriding process. Three samples were chosen in the shape of tapered cylindrical shapes with diameter of 10 mm and length of 40 mm. The specimens were subjected to 60 Minutes, 120 Minutes, 180 Minutes and named as SBN1, SBN2, SBN3 respectively. One untreated specimen is kept aside for the comparison purpose with the treated specimens. After the heat treatment process wear test were conducted by pin on disc wear test machine. Then the hardness test is carried out using the Rockwell hardness test. The microscopic images were taken using Scanning electron microscope. The results were compared and the best wear resistant material is chosen for the required application.

EFFECT OF SALT BATH NITRIDING TIME ON THE PERFORMANCES OF 304 STAINLESS STEEL

In this study, salt bath nitriding was carried out at 565℃ for various times for 304 stainless steel (304SS). The effect of salt bath nitriding time on the microstructure, micro-hardness and wear resistance was investigated systematically. The results showed a nitriding layer was formed during salt bath nitriding, and the thickness of effective hardening layer is duration dependant. The maximum microhardness value of 1200HV0.01 was obtained at optimal duration of 150min, which was five times higher than that of the untreated sample. And the wear resistance could be significantly improved by salt bath nitriding, the lowest weight loss after wear resistance was obtained while nitriding for 150min, which was one tenth of that of untreated sample.

ANALISIS PENGARUH WAKTU TAHAN SALT BATH NITRIDING TERHADAP KETEBALAN NITRIDE LAYER DAN KEKERASAN PERMUKAAN PADA MATERIAL SUH35 (JIS: SUH35)

Time is a parameter that is very influential on the productivity and product quality from the nitriding process. This study aims to find out how much effect of the holding time in salt bath nitriding process to the nitride layer thickness and surface hardness of SUH35 material. This salt bath nitriding process used chemical salt with cyanide content (CNˉ) 1.5% - 4.5%, and cyanate content (CNOˉ) 28% - 32%. The workpiece used in this study is a cylindrical SUH35 material with diameter 5 mm. Temperature that used for salt bath nitriding process is 580 ° C with a variation of the holding time is 20 minutes, 25 minutes and 35 minutes. From this study, results of the data obtained are, with a holding time 20 minutes the average thickness of the nitride layer SUH35 material is 12.74 µm and the average surface hardness is 556.96 Hv. With a holding time 25 minutes the average thickness of the nitride layer SUH35 material is 16.07 µm and the average surface hardness is 792.18 Hv. With a holding time 35 minutes the average thickness of the nitride layer SUH35 material is 20.17 µm and the average surface hardness is 989.94 Hv.