Effect of Boronizing and WC Coating on the High Temperature Mechanical Behavior of AISI 321 Stainless Steel

In the current paper, the effect of two different coating techniques of boronizing and tungsten carbide (WC) coating on the room and high temperature tensile behavior of the AISI 321 stainless steel were investigated. Consequently, the fracture morphology observations were conducted via scanning electron microscopy (SEM) to inspect the variation of fracture mechanisms after implementing different coating methods. The results of tensile tests at room temperature revealed that despite boronizing reduced the yield strength of the sample due to the softening and grain growth at high coating temperature, the dispersion of boron particles improved the work hardening and ductility of boronized AISI 321. 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 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.