Effect of thermal aging on the fatigue crack growth behavior of cast duplex stainless steels

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2015-11, Vol.22 (11), p.1163-1170
• Main Authors: Lü, Xu-ming, Li, Shi-lei, Zhang, Hai-long, Wang, Yan-li, Wang, Xi-tao
• Format: Article
• Language: English
• Subjects: Aging; Aging (metallurgy); Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Crack closure; Crack propagation; Duplex stainless steels; Fatigue cracks; Fatigue failure; Ferrite; Fracture mechanics; Fracture surfaces; Glass; Hardness; Materials Science; Metallic Materials; Natural Materials; Plastic deformation; Spinodal decomposition; Surfaces and Interfaces; Thin Films; Tribology; 双相不锈钢; 塑性变形能力; 扩展行为; 热时效; 疲劳裂纹扩展; 表面粗糙度; 裂纹扩展路径; 铸造
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-015-1181-0

The effect of thermal aging on the fatigue crack growth（FCG） behavior of Z3CN20？09M cast duplex stainless steel with low ferrite content was investigated in this study. The crack surfaces and crack growth paths were analyzed to clarify the FCG mechanisms. The microstructure and micromechanical properties before and after thermal aging were also studied. Spinodal decomposition in the aged ferrite phase led to an increase in the hardness and a decrease in the plastic deformation capacity, whereas the hardness and plastic deformation capacity of the austenite phase were almost unchanged after thermal aging. The aged material exhibited a better FCG resistance than the unaged material in the near-threshold regime because of the increased roughness-induced crack closure associated with the tortuous crack path and rougher fracture surface; however, the tendency was reversed in the Paris regime because of the cleavage fracture in the aged ferrite phases.