API 571 Certification (Corrosion & Materials) Practice Test

What type of stainless steel is noted for its embrittlement at high temperatures?

1. 300 series Stainless Steel

2. 400 series Stainless Steel

3. Duplex Stainless Steel

4. Cast Iron

The correct answer is: 300 series Stainless Steel

The 300 series stainless steel is austenitic and is well-known for its susceptibility to embrittlement at elevated temperatures, particularly when exposed to prolonged heating in the range of 1000°F to 1500°F (538°C to 815°C). This embrittlement occurs due to the precipitation of carbides at grain boundaries, leading to a reduction in ductility and toughness. Specifically, the formation of chromium carbides can occur, which consumes chromium from the surrounding matrix and can lead to decreased corrosion resistance in addition to embrittlement. This type of embrittlement, particularly sensitization, is a critical consideration in applications such as heat exchangers and piping systems where high temperatures may be encountered. The 300 series is widely used in various industries due to its excellent corrosion resistance, but awareness of its potential for embrittlement at high temperatures is essential during material selection and processing to avoid failures. In contrast, while the 400 series stainless steel is ferritic and has some high-temperature properties, it does not exhibit the same level of sensitization issues as the 300 series. Duplex stainless steels exhibit a combination of austenitic and ferritic structures and have better resistance to embrittlement compared to the 300 series. Cast iron