Study on Stress Corrosion Cracking of Austenitie Stainless Steel and its Welded Joint under Pulsating Load

Propagation Time of Base Metal under Pulsating Trapezoid Load

Abstract

In the first stage of the research on stress corrosion cracking under dynamic load, we tried to study the phenomenon under pulsating trapezoid load (Fig.4).
The tested material is AISI 304 stainless steel and the corrosion medium is a boiling solution of 42 percent MgCl₂ (B.P.: 154°C). The apparatus used in this report is a constant tensile loading type and we can change the load time and the no-load time, arbitrarily.
The results obtained from this experiment are summarized as follows:
1) The damage due to stress corrosion cracking under pulsating trapezoid load is not equal to the accumulated value of static damage. This damage is not only influenced by the dynamic effect due to the pulsating load but also by the length of no-load time.
2) We can presume the propagation time under the following assumption: the total sum of the damages due to 1) load time, 2) no-load time and 3) dynamic effect is equal to the damage under static load.
3) In the case of the ratio of load time to no-load time being constant, the crack propagation time is prolonged by the prolongation of the loading period.