Exploring Stress Corrosion Cracking in Magnesium-Based Alloys Exposed to Potassium Chromate in Automotive Applications

Abstract

<div class="section abstract"><div class="htmlview paragraph">Magnesium alloys possess a unique combination of benefits stemming from their exceptional strength-to-weight ratio and reduced density. The aforementioned attributes render them notably attractive for utilization in automotive and aeronautical sectors. Furthermore, these alloys are gaining significant interest from the industry because of their outstanding dimensional stability, excellent ability to dampen vibrations, high recyclability, and good castability. They also exhibit superior stiffness, among other attributes. Nonetheless, magnesium and its alloys face several noteworthy challenges that limit their industrial utilization. These include low resistance to deformation over time, limited stability at high temperatures, restricted malleability, poor ductility, and inadequate resistance to corrosion. This study aims to investigate the phenomenon of stress corrosion cracking in magnesium alloy when exposed to potassium chromate. Addition of Ca showed better mechanical properties. A proof ring test was conducted NaCl-K2CrO4 solution at 60% YS value of base material, shows that the AZ91+4%Ca is having the least stress corrosion resistance. Threshold stress for AZ91 with 1%, 2%, 3% wt% Ca is found to be higher than the applied stress value in both the corrosion environment, so that the material has not failed even after the test duration of 720h. The observed stress corrosion resistance in AZ91+4% Ca is unsatisfactory due to the brittle nature of the large Al2Ca phase. In contrast, AZ91 alloys containing 1%, 2%, or 3% Ca, which have a lower proportion of Al2Ca phase, exhibit improved mechanical properties and enhanced resistance to stress corrosion cracking (SCC).</div></div>