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フェライト系

These steels are, in principle, ferritic at all temperatures. This is achieved by a low content of austenite forming elements, mainly nickel, and a high content of ferrite forming elements, mainly chromium.

Ferritic types, such as 4003 and 4016, are mainly used for household utensils, catering equipment and other purposes where corrosion conditions are not particularly demanding.

Steels with high chromium content, such as 4762 with 24% chromium, are used at high temperatures where their resistance to sulphurous flue gages is an advantage. However, the risk of 475 °C embrittlement and precipitation of brittle sigma phase in high-chromium steels must always be taken into consideration.

Ferritic steels, such as 4521 with extremely low carbon and nitrogen contents, find greatest use where there is a risk of stress-corrosion cracking.

Ferritic steels have slightly higher yield strength (Rp 0.2) than austenitic steels, but they have less elongation at fracture. Another characteristic that distinguishes ferritic steel from austenitic material is that ferritic steels have much lower strain hardening.