Beta Alloys

Abstract

In contrast to α+β alloys, β alloys do not transform martensitically upon quenching to room temperature, resulting in a metastable β phase. The α phase can be precipitated from the metastable β phase as very fine, undeformable particles (platelets) with a high volume fraction, see Sect. 2.8.2. Therefore, the main characteristic of β alloys is that they can be hardened to much higher yield stress levels than α+β alloys. Another advantage of β alloys is that they can be processed at lower temperatures than α+β alloys, and some heavily stabilized β alloys are even cold deformable. Further, the corrosion resistance of β alloys is equal to or better than that of α+β alloys. The β alloys are especially good in environments where hydrogen pickup is possible because the β phase has a higher hydrogen tolerance than the α phase. It is not surprising that the usage of β alloys has been slowly but steadily increasing over the recent years.