Aging effects on the mechanical properties of alumina-forming austenitic stainless steels

作者：Bei H^*; Yamamoto Y; Brady M P; Santella M L

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2010, 527(7-8): 2079-2086.

DOI：10.1016/j.msea.2009.11.052

• Mechanical characterization
• Aging
• Intermetallics
• Steel
• Fracture

Isothermal aging and tensile evaluation were conducted for recently developed alumina-forming austenitic stainless steels (AFAs). Microstructural observation reveals that NiAl-type B2 and F(e)2(Mo,Nb)type Laves phase precipitates form as dominant second phases in the austenitic matrix during aging at 750 degrees C. At room temperature these precipitates increase the strength but decrease the ductility of the AFA alloys. However, when tested at 750 degrees C, the AFA alloys did not show strong precipitation hardening by these phases, moreover, the elongation to fracture was not affected by aging. Fracture surface and cross-sectional microstructure analysis after tensile testing suggests that the difference of mechanical behaviors between room temperature and 750 degrees C results from the ductile-brittle transition of the B2 precipitates. At room temperature, B2 precipitates are strong but brittle, whereas they become weak but ductile above the ductile-brittle transition temperature (DBTT).

• 出版日期2010-3-25