Effect of Solution Annealing on Fatigue Crack Propagation in the AISI 304L TRIP Steel

0544866 - ÚFM 2022 RIV CH eng J - Journal Article
Jambor, Michal - Vojtek, Tomáš - Pokorný, Pavel - Šmíd, Miroslav
Effect of Solution Annealing on Fatigue Crack Propagation in the AISI 304L TRIP Steel.
Materials. Roč. 14, č. 6 (2021), č. článku 1331. E-ISSN 1996-1944
R&D Projects: GA MŠMT(CZ) LQ1601; GA ČR(CZ) GJ19-25591Y
Institutional support: RVO:68081723
Keywords : solution annealing * fatigue crack propagation * martensitic transformation * crack closure * 304L steel * effective threshold * load shedding
OECD category: Materials engineering
Impact factor: 3.748, year: 2021
Method of publishing: Open access
https://www.mdpi.com/1996-1944/14/6/1331

Fatigue crack propagation in near-threshold regime was studied in the 304L austenitic stainless steel in two microstructural states: as-received (AR) with finer microstructure and low susceptibility to the transformation-induced plasticity (TRIP) effect, and solution-annealed (SA) with coarser microstructure and higher susceptibility to TRIP. At the load ratio R = 0.1 the threshold was higher in the SA state than in the AR state due to coarser grains and possibly the TRIP effect. In order to clarify the role of crack closure, experiments at R = 0.7 were done. The threshold in the SA state was still higher by 1 MPa center dot m(0.5). This effect was identified as crack tip shielding induced by phase transformation, an example of a non-closure shielding effect. Higher resistance to crack growth in the SA state was attributed to promoted martensitic transformation in non-favorable oriented grain families rather than thicker martensite layers in the crack path area. The conclusions were verified by experiments at R = 0.7 and temperature 150 degrees C > M-s which did not reveal any notable difference in thresholds. However, the threshold values were affected by the load-shedding gradient C =d Delta K/da, which had to be equalized in both experimental setups inside and outside the furnace.
Permanent Link: http://hdl.handle.net/11104/0321664