Farklı yüzey işlemlerinin ınconel 625 süper alaşım ve aısı 321 paslanmaz çelik için çekme ve aşınma davranışlarına etkisi

AISI 321 stainless steel and Inconel 625 superalloy are utilized in an extensive range of applications such as aircraft engines, nuclear powerplants and industrial furnaces due to their excellent mechanical properties at high temperatures. The surface treatment of these materials is necessary due to the extreme working environments. Boronizing and WC coating is the most important surface hardening processes. In the current work, the effect of boronizing and WC coating on the wear performance and tensile behavior of AISI 321 and Inconel 625 at room and high temperature were investigated. Furthermore, damage mechanisms and fracture morphologies were observed using Scanning Electron Microscopy (SEM) and optical profilometry. According to room temperature tensile test results, yield strength (YS) and ultimate tensile strength (UTS) of the samples are reduced after the boronizing process. This strength reduction may be attributed to the softening of the material throughout the boronizing process at high temperature of 1100°C. On the other hand, ductility of the Inconel 625 samples has been decreased due to dynamic strain aging at 600°C. The yield strength of the boronized samples was significantly reduced because of the decomposition of boron particles throughout tensile test at elevated temperatures. Consequently, the fracture morphology observations revealed that the main fracture mechanism of both coated and uncoated conditions at high temperature was a ductile fracture represented by deep dimples. However, the boronized sample was drastically affected by grain growth during boronizing process and decomposition of dispersed particles. In contrast, the strain to failure of the WC coated sample was decreased due to the fast fracture of the ceramic WC layer at both room and high temperature tensile tests. Furthermore, results of SEM revealed that particle decomposition occured on the fracture surface of the boronized 321 stainless steel represented by dispersed boron particles on the edges of the dimples after failure at high temperature. Due to the high hardness and heat resistance of WC coated layer, the friction coefficient of the sample was higher than that of boronized and uncoated conditions at room tempearature. It was seen that the wear rates of boronized and WC coated AISI 321 were extremely lower than that of uncoated sample. On the other hand, at 600°C, WC coated wear rate was still lower but uncoated and boronized samples' values were similar to the room temperature results. Inspection of room temperature the wear test results revealed that the wear rates of Inconel 625 uncoated and coated samples were similar to the results of AISI 321. WC coated samples' wear rate was tremendously lower than the others. At high temperature, the boronized Inconel 625 had higher friction coefficient than the WC coated sample. A fluctuation was also noticed, which is linked to boron particle aggregation on the surface at high temperatures.