Definition - What does Huey Test mean?
The Huey test is a form of corrosion testing that makes use of nitric solution nitric acid. This test is primarily utilized to identify the susceptibility of stainless steel to corrosion, specifically the intergranular type.
Corrosionpedia explains Huey Test
In the Huey test, samples are subjected to boiling for five consecutive periods over a period of 48 hours each time. The solution that is used in this form of testing is 65% reflux nitric acid. In this test, the weight of lost metal is measured as loss in inches per month (ipm) or inches per year (ipy). This test can also be used to measure optimal attack depth. However, it is not included in a typical assessment.
In the Huey test, the environment is highly oxidized and serves as a way to see whether the sample has undergone correct heating. Thus, this test can be utilized to perform a comparison involving various steels to other objects' corrosion resistance in less oxidizing setups. It is recommended for detecting areas depleted of chromium and precipitations that exist among metals such as sigma phase. It is mainly used for objects that come in contact with highly oxidizing elements such as nitric acid.
This test is specifically designed to help the material undergo sensitization and locate grain boundary precipitation and segregation. The usual treatment for sensitization is at 650° to 700°C or 1200° to 1290° F. This should be performed over a period of 30 to 120 minutes, along with air cooling.
Under the mentioned temperature series, carbide grain or secondary phase precipitation is hastened. This leads to depletion involving the adjoining area, which may be chromium or molybdenum in the case of phase precipitation of molybdenum. Due to the depletion, the area of grain boundary is prone to attack while most of the sample is immune.