PSI - Issue 17

Available online at www.sciencedirect.com Structural Int grity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 17 (2019) 331–338

ICSI 2019 The 3rd International Conference on Structural Integrity The most frequent failure causes in super ferritic stainless steels: are they really super? C. R F. Azevedo a , A. F. Padilha a, * a Department of Metallurgical and Materials Engineering, Escola Politécnica, Universidade de São Paulo, Av. Professor Mello Moraes, 2463, São Paulo, 05508-030, Brazil. Ferritic stainless steels (FSSs) are classified according to their “generation”, where the 4 th generation was commercially branded as super ferritic stainless steels (SFSSs). SFSSs contain C content below 0.02% C, Cr above 25%, Ni and Mo between 2 and 4% and eventual additions of Nb or Ti. The combination of good mechanical properties and top corrosion resistance makes the SFSSs candidates for applications in chemical, petrochemical and desalination plants. However, SFSS components might be subjected to mechanical embrittlement and environmentally induced failures, especially when these components are exposed to temperatures above 300°C, which promotes the precipitation of stable and deleterious phases, such as sigma, chi and Laves phases, and α’ clusters. The main properties of the SFSSs will be compared other generations of FSSs to provide a broader outlook of the boundary conditions for their selection. Finally, the main phase transformations of the SFSSs will be concisely presented along with their typical microstructures, microfractographies and crack propagation paths in order to depict the role of these stable and deleterious phases on the processing and service life of SFSS components. ICSI 2019 The 3rd International Conference on Structural Integrity The most frequent failure causes in super ferritic stainless steels: are they really super? C. R F. Azevedo a , A. F. Padilha a, * a Department of Metallurgical and aterials Engineering, Escola Politécnica, Universidade de São Paulo, Av. Professor Mello Moraes, 2463, São Paulo, 05508-030, Brazil. Abstract Ferritic stainless steels (FSSs) are classified according to their “gen ration”, where the 4 th generation was commercially branded s super ferritic stainless steels (SFSSs). SFSSs contain C content below 0.02% C, Cr ab ve 25%, Ni and Mo betwe n 2 and 4% and eventual additions f Nb or Ti. The combination of good mechanical properties and top corrosion resistance makes the SFSSs candidates for applications i chemical, petrochemical and desalination plants. However, SFSS components might be subj cted to mechanical embrittlement and environmentally induced failures, especially when these components are exposed to temperatures abov 300°C, which romotes t e precipitation of stabl and del terious phases, such as sigma, chi and Laves phases, a α’ lusters. The main prop rties of the SFSSs will be compared other generations of FSSs to provide a broader outlook of the boundary conditions f r their selection. Finally, the main ph se transformations of the SFSSs will be concisely presented along with their typical microstructures, microfractographies and crack propagation paths in order to depict the role of these stable and deleterious phases on the processing and service life of SFSS components. Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

Keywords: Super ferritic stainless steels; Failures causes; Stable and deleterious phases; Limitations. Keywords: Super ferritic stainless steels; Failures causes; Stable and deleterious phases; Limitations.

1. Introduction The discovery of martensitic (MSSs), austenitic (ASSs) and ferritic stainless steels (FSSs) occurred almost simultaneously. Brearley discovered the 12%Cr-0.2%C MSSs in 1912 in Sheffield, while the ASSs were developed in Essen, Krupp. In 1911, Dantsizen initiated his experiments with ferritic alloys containing from 14 to 16% Cr and 1. Introduction The discovery of martensitic (MSSs), austenitic (ASSs) and ferritic stainless steels (FSSs) occurred almost simultaneously. Brearley discovered the 12%Cr-0.2%C MSSs in 1912 in Sheffield, while the ASSs were developed in Essen, Krupp. In 1911, Dantsizen initiated his experiments with ferritic alloys containing from 14 to 16% Cr and

* Corresponding author. Tel.: +55-11-3091-5239; fax: +55-11-3091-5243. E-mail address: padilha@usp.br * Correspon ing author. Tel.: +55-11-3091-5239; fax: +55-11-3091-5243. E-mail address: padilha@usp.br

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.044