Abstract
This research was carried out to study the effect of time on the compound layer of AISI 4140 steel in salt bath nitriding. The nitriding process were implemented on AISI 4140 steel in salt bath component for different times (from 1 h to 10 h) at 580 °C. Samples of AISI 4140 steel were treated and characterized (at surface and core of samples) through the following technique: optical microscopy, scanning electron microscopy, X-ray diffraction (XRD) and microhardness tester. Shows that thick compound layers are formed during continuous salt bath nitriding. The thickness of the compound layer and surface hardness increases with increasing time.
Highlights
Thermochemical nitriding treatments are used heavily in many kinds of steel because frequent use of steels in all ranges of industry [1, 2]
2 Experimental procedure 2.1 Material and methods The material used for the investigation was AISI 4140 steel with the following chemical compositions: 0.47 C, 0.93 Cr, 0.2 Mo, 0.79 Mn, 0.13 Ni, 0.25 Si, 0.015 P, 0.037 S and balance Fe, and the steel has the microstructure of martensitic (Fig. 1) with an average hardness of 348 HV
It can be clearly seen that a compound layer is formed on the sample surface during salt bath nitriding
Summary
Thermochemical nitriding treatments are used heavily in many kinds of steel because frequent use of steels in all ranges of industry [1, 2]. Nitriding is a surface thermochemical treatment technique used to introduce and install nitrogen atoms into metallic materials, surface to improve their surface hardness, mechanical properties, as well as wear [3, 4] and corrosion resistance [5, 6], as well as fatigue life [7, 8, 9]. The primary aim of the process of salt bath nitriding (SBN) [12] is to obtain high surface hardness, improve mechanical properties and increase wear resistance, fatigue life, dimensional stability and corrosion resistance as a result of the presence of compounds formed at the surface, in addition to a zone of diffused nitrogen in solid solution with the base material, subjacent to the compound layer [13, 14, 15]. Nitriding is one type of the most widely used thermo-chemical treatments in the industry, which produces strong and shallow case with high compressive residual stresses on the surface of steel components such as gears, crankshafts, dies and tools [16, 17, 18, 19]. Salt bath nitriding is commonly used as an alternative to high temperature conventional heat
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
