Caustic Embrittlement

Abstract

The paper contains the results of experimental work on caustic embrittlement. The type of apparatus chosen was based on one used in recent American work carried out by Straub and Bradbury (1938). In this, the solution to be tested is contained in a hollow sealed tubular specimen, heated to any desired temperature in the steam boiler range, and subjected to a tensile load by means of a spring. It has not been possible to reproduce the results claimed by Straub, but a number of examples of intergranular cracking have been produced. Some of these have been obtained when using dilute solutions containing amounts of NaOH and silicate such as would be found in boiler waters. There is evidence that embrittlement occurs more readily in poor-quality steel and under conditions of non-uniform stress distribution, but it has not been possible to reproduce results with any degree of certainty. A few experiments with an entirely different type of specimen have been carried out; and in these, intergranular failures have also been produced. The paper also contains a survey of the more important literature on caustic embrittlement published between 1935 and 1941.