Effect of Thermal Cycles on Corrosion Resistance in a Type 304 Stainless Steel (Report 1)

Abstract

To study the corrosion resistance of weld heat-affected zone in a type 304 stainless steel the author used synthetic specimens given thermal cycles with, current heating.
Zero to twenty thermal cycles were given at various peak temperatures. Then the relationship between the corrosion resistance and the behaviour of carbide was investigated on all of the specimens given thermal cycles. The following results were obtained.
(1) In the specimens given thermal cycles at the peak temperatures 650° and 800°C, the susceptibility. for corrosion increased with the number of thermal cycles.
(2) In the specimens given thermal cycles at the peak temperatures 650°and 800°C, the corrosion on grain boundaries was observed as a local etching around the carbide particles.
(3) In the observation of carbon extraction replica of the specimens given thermal cycles at the peak temperatures 650°and 800°C, carbide particles were observed, precipitating on grain boundaries as isolated dendritic particles. In the specimens given thermal cycles at the peak temperatures 500°, 1000°and 1200°C no carbide particles were observed.