Relationship between manufacturing defects and fatigue properties of additive manufactured austenitic stainless steel

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:765

Article

Smith, Thale R.^1,2  Sugar, Joshua D.¹  Schoenung, Julie M.³  San Marchi, Chris¹ 

[1] Sandia Natl Labs, Livermore, CA 94550 USA

[2] Univ Calif Davis, Davis, CA 95616 USA

[3] Univ Calif Irvine, Irvine, CA 92697 USA

关键词: Additive manufacturing (AM);    Manufacturing defects;    Fatigue;    Austenitic stainless steel;   

DOI  :  10.1016/j.msea.2019.138268

来源: Elsevier

【 摘 要 】

Tensile properties, fatigue crack initiation, fatigue crack growth rate, and fatigue life are evaluated in 304L austenitic stainless steel fabricated by directed energy deposition (DED). Large lack of fusion (LoF) defects (often > 1 mm in length) significantly reduce ultimate tensile strength and ductility, as well as accelerate fatigue crack initiation and reduce fatigue life. In comparison, small spherical defects (< 100 mu m in diameter) have less effect on tensile and fatigue properties. Fatigue crack growth rate is less severely affected by defects than other properties, showing only local acceleration in the proximity of LoF defects. Therefore, shorter fatigue life is attributed to the role of LoF defects on facilitating fatigue crack initiation and to a lesser extent fatigue crack propagation. Additionally, the fatigue life can be normalized for defects by considering their effect on ultimate tensile strength, suggesting that in the limit of low defect population, the fatigue strength of additively manufactured stainless steel is similar to conventional wrought materials.

【 授权许可】

Free