Factors affecting impact toughness in stabilized intermediate purity 21Cr ferritic stainless steels and their simulated heat-affected zones
|Author:||Anttila, Severi1; Alatarvas, Tuomas2; Porter, David A.1|
1Materials and Production Engineering, University of Oulu, Oulu, Finland, 358
2Process Metallurgy, University of Oulu, Oulu, Finland, 358
|Online Access:||PDF Full Text (PDF, 6.4 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2019112243755
|Publish Date:|| 2019-11-22
The correlation between simulated weld heat-affected zone microstructures and toughness parameters has been investigated in four intermediate purity 21Cr ferritic stainless steels stabilized with titanium and niobium either separately or in combination. Extensive Charpy V impact toughness testing was carried out followed by metallography including particle analysis using electron microscopy. The results confirmed that the grain size and the number density of particle clusters rich in titanium nitride and carbide with an equivalent circular diameter of 2 µm or more are statistically the most critical factors influencing the ductile-to-brittle transition temperature. Other inclusions and particle clusters, as well as grain boundary precipitates, are shown to be relatively harmless. Stabilization with niobium avoids large titanium-rich inclusions and also suppresses excessive grain growth in the heat-affected zone when reasonable heat inputs are used. Thus, in order to maximize the limited heat-affected zone impact toughness of 21Cr ferritic stainless steels containing 380 to 450 mass ppm of interstitials, the stabilization should be either titanium free or the levels of titanium and nitrogen should be moderated.
Metallurgical and materials transactions. A, Physical metallurgy and materials science
|Pages:||5879 - 5889|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
216 Materials engineering
214 Mechanical engineering
This research work was carried out as part of the Breakthrough Steels and Applications (BSA) program of the Digital, Internet, Materials & Engineering Co-Creation (DIMECC). The work of S.A. was partly funded by the University of Oulu Graduate School of Advanced Materials Doctoral Programme (ADMA-DP). The authors are grateful to the Finnish Funding Agency for Technology and Innovation (TEKES) and Outokumpu Stainless Oy for financial support.
© The Minerals, Metals & Materials Society and ASM International 2017.