{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:19:10Z","timestamp":1760239150360,"version":"build-2065373602"},"reference-count":39,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2020,9,23]],"date-time":"2020-09-23T00:00:00Z","timestamp":1600819200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>The energy evolution, fatigue life and failure behaviour of dissimilar Al\/steel keyhole-free Friction stir spot welding (FSSW) joints were studied under different fatigue loads. The absorption energy of fatigue fracture, the fracture mechanism and the sensitivity of the fatigue limits to the fatigue load parameters were analysed. It was found that the stress ratio R determines the fatigue limit Ff, while the fatigue limit Ff is not sensitive to the loading frequency. The high-frequency fatigue load will increase the displacement deformation \u03bc and fatigue fracture absorption energy Ea of the spot-welded joint, which are larger under asymmetric fatigue loading than those under symmetrical fatigue loading. At the same time, the symmetrical fatigue load can form the steady-state hysteresis loop, while asymmetric fatigue loading cannot, but asymmetric fatigue loading exhibits the displacement increment of fatigue softening. The fracture failure of spot-welded joints is a multiple crack source and the mixed-mode of ductile and brittle fracture mechanism, which exhibits typical fatigue striations in the fatigue fractures.<\/jats:p>","DOI":"10.3390\/ma13194247","type":"journal-article","created":{"date-parts":[[2020,9,24]],"date-time":"2020-09-24T02:56:43Z","timestamp":1600916203000},"page":"4247","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Effect of Loading Methods on the Fatigue Properties of Dissimilar Al\/Steel Keyhole-Free FSSW Joints"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4703-2790","authenticated-orcid":false,"given":"Zhongke","family":"Zhang","sequence":"first","affiliation":[{"name":"School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yang","family":"Yu","sequence":"additional","affiliation":[{"name":"School of Materials Science and Engineering, Tongji University, Shanghai 201804, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huaxia","family":"Zhao","sequence":"additional","affiliation":[{"name":"Aeronautical Key Laboratory for Welding and Joining Technologies, AVIC Manufacturing Technology Institute AECC, Beijing 100024, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hui","family":"Tong","sequence":"additional","affiliation":[{"name":"SAIC MOTOR Commercial Vehicle Technical Center, Body Department, Shanghai 200090, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,9,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"520","DOI":"10.1016\/j.ijfatigue.2019.04.026","article-title":"Experimental investigation and numerical modeling of the fatigue crack growth in friction stir spot welding of lap-shear specimen","volume":"125","author":"Shahani","year":"2019","journal-title":"Int. J. Fatigue"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1007\/s11665-013-0768-8","article-title":"Effect of Tool Rotation Rate on Microstructure and Mechanical Behavior of Friction Stir Spot-Welded Al\/Cu Composite","volume":"23","author":"Shiraly","year":"2014","journal-title":"J. Mater. Eng. Perform."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"6","DOI":"10.5781\/JWJ.2016.34.3.6","article-title":"Effect of Circumferential Tool Path Control on Friction Stir Spot Welding of Al\/Fe Dissimilar Metal Joint","volume":"34","author":"Yoon","year":"2016","journal-title":"J. Weld. Join."},{"key":"ref_4","first-page":"1063","article-title":"Connection mechanism research on friction stir spot welding without keyhole between magnesium and steel dissimilar alloys","volume":"18","author":"Wang","year":"2014","journal-title":"Mater. Res. Innov."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Zhang, Z., Yu, Y., Zhao, H., and Wang, X. (2019). Interface Behavior and Impact Properties of Dissimilar Al\/Steel Keyhole-Free FSSW Joints. Metals, 9.","DOI":"10.3390\/met9060691"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1016\/j.matdes.2016.01.066","article-title":"Refilled friction stir spotwelding of aluminum alloy to galvanized steel sheets","volume":"94","author":"Dong","year":"2016","journal-title":"Mater. Des."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2850","DOI":"10.1007\/s11661-011-0677-0","article-title":"Friction Stir Brazing: A Novel Process for Fabricating Al\/Steel Layered Composite and for Dissimilar Joining of Al to Steel","volume":"42A","author":"Zhang","year":"2011","journal-title":"Met. Mater. Trans. A"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"350","DOI":"10.1016\/j.matdes.2012.12.007","article-title":"Microstructure and mechanical properties of dissimilar Al alloy\/steel joints prepared by a flat spot friction stir welding technique","volume":"47","author":"Sun","year":"2013","journal-title":"Mater. Des."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"854","DOI":"10.1007\/s11661-013-2036-9","article-title":"Friction Stir Welding of Stainless Steel to Al Alloy: Effect of Thermal Condition on Weld Nugget Microstructure","volume":"45A","author":"Ghosh","year":"2014","journal-title":"Met. Mater. Trans. A"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4505","DOI":"10.1016\/j.msea.2010.03.097","article-title":"Intermetallic compounds in Al 6016\/IF-steel friction stir spot welds","volume":"527","author":"Bozzi","year":"2010","journal-title":"Mat. Sci. Eng. A-Struct"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.1007\/s00170-019-04716-9","article-title":"Hook formation and joint strength in friction stir spot welding of Al alloy and Al-Si-coated hot-press forming steel","volume":"106","author":"Kang","year":"2020","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1016\/j.matdes.2017.04.084","article-title":"Strength and failure analysis of similar and dissimilar friction stir spot welds: Influence of different tools and pin geometries","volume":"127","author":"Garg","year":"2017","journal-title":"Mater. Des."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"443","DOI":"10.1179\/136217109X427494","article-title":"Effect of reduced or zero pin length and anvil insulation on friction stir spot welding thin gauge 6111 automotive sheet","volume":"14","author":"Bakavos","year":"2009","journal-title":"Sci. Technol. Weld. Join."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1007\/s11665-012-0244-x","article-title":"Microstructure and Mechanical Performance of Friction Stir Spot-Welded Aluminum-5754 Sheets","volume":"22","author":"Pathak","year":"2013","journal-title":"J. Mater. Eng. Perform."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"466","DOI":"10.1080\/13621718.2015.1125407","article-title":"Dissimilar Al\/steel friction stir spot welding: To penetrate into the lower steel sheet or not?","volume":"21","author":"Fereiduni","year":"2016","journal-title":"Sci. Technol. Weld. Join."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"R13","DOI":"10.1007\/BF03266697","article-title":"Friction stir spot welds between aluminium and steel automotive sheets: Influence of welding parameters on mechanical properties and microstructure","volume":"53","author":"Figner","year":"2009","journal-title":"Weld. World"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.msea.2006.06.126","article-title":"Structure-properties relations in spot friction welded (also known as friction stir spot welded) 6111 aluminum","volume":"441","author":"Mitlin","year":"2006","journal-title":"Mat. Sci. Eng. A-Struct."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1007\/s40194-015-0268-6","article-title":"Experimental failure study of friction stir spot welded similar and dissimilar aluminum alloys","volume":"60","author":"Sajed","year":"2016","journal-title":"Weld. World"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1187","DOI":"10.1016\/j.scriptamat.2005.07.016","article-title":"Fatigue properties of friction stir welds in Al 5083 alloy","volume":"53","author":"Zhou","year":"2005","journal-title":"Scr. Mater."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1956","DOI":"10.1016\/j.ijfatigue.2008.01.006","article-title":"Effect of re-filling probe hole on tensile failure and fatigue behaviour of friction stir spot welded joints in Al-Mg-Si alloy","volume":"30","author":"Uematsu","year":"2008","journal-title":"Int. J. Fatigue"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1179\/136217108X338908","article-title":"Comparison of fatigue behaviour between resistance spot and friction stir spot welded aluminium alloy sheets","volume":"14","author":"Uematsu","year":"2009","journal-title":"Sci. Technol. Weld. Join."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1823","DOI":"10.1016\/j.proeng.2010.03.196","article-title":"Evaluation of dynamic defect detection in FSSW welded joints under fatigue tests","volume":"2","author":"Malafaia","year":"2010","journal-title":"Procedia Eng."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2494","DOI":"10.1007\/s11665-015-1534-x","article-title":"Fatigue Damage Evaluation of Friction Stir Spot Welded Cross-Tension Joints Under Repeated Two-Step Force Amplitudes","volume":"24","author":"Ogawa","year":"2015","journal-title":"J. Mater. Eng. Perform."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"855","DOI":"10.1007\/s11665-010-9725-y","article-title":"Statistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321","volume":"20","author":"Grujicic","year":"2011","journal-title":"J. Mater. Eng. Perform."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"369","DOI":"10.1016\/j.msea.2012.11.076","article-title":"Influence of structural integrity on fatigue behavior of friction stir spot welded AZ31 Mg alloy","volume":"564","author":"Rao","year":"2013","journal-title":"Mat. Sci. Eng. A-Struct."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"959","DOI":"10.1007\/s12666-015-0533-9","article-title":"High Cycle Fatigue Behaviour of Friction Stir Lap Welded 6061 Aluminium Alloy to Coated Steel Sheet Joint","volume":"68","author":"Das","year":"2015","journal-title":"Trans. Indian Inst. Met."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.ijfatigue.2013.10.004","article-title":"Non-uniform deformation in a friction stir welded Mg-Al-Zn joint during stress fatigue","volume":"59","author":"Yang","year":"2014","journal-title":"Int. J. Fatigue"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/j.ijfatigue.2013.11.021","article-title":"Fatigue analyses for swept friction stir spot welds in lap-shear specimens of alclad 2024-T3 aluminum sheets","volume":"61","author":"Su","year":"2014","journal-title":"Int. J. Fatigue"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/j.msea.2012.11.039","article-title":"Lap shear strength and fatigue behavior of friction stir spot welded dissimilar magnesium-to-aluminum joints with adhesive","volume":"562","author":"Chowdhury","year":"2013","journal-title":"Mat. Sci. Eng. A-Struct."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1016\/j.ijfatigue.2013.12.009","article-title":"Failure modes and fatigue behavior of conventional and refilled friction stir spot welds in AA 6061-T6 sheets","volume":"61","author":"Venukumar","year":"2014","journal-title":"Int. J. Fatigue"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1761","DOI":"10.1007\/s40194-019-00773-6","article-title":"Welding parameter selection and short fatigue crack growth of dissimilar aluminum alloy friction stir welded joint","volume":"63","author":"Sun","year":"2019","journal-title":"Weld. World"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1949","DOI":"10.1016\/S1003-6326(13)62682-5","article-title":"Fatigue behavior of friction stir spot welded AZ31 Mg alloy sheet joints","volume":"23","author":"Luo","year":"2013","journal-title":"Trans. Nonferrous Met. Soc. China"},{"key":"ref_33","unstructured":"Kakiuchi, T., Uematsu, Y., and Suzuki, K. (2016, January 20\u201324). Evaluation of fatigue crack propagation in dissimilar Al\/steel friction stir welds. Proceedings of the 21st European Conference on Fracture, ECF 21, Catania, Italy."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"105556","DOI":"10.1016\/j.ijfatigue.2020.105556","article-title":"Microstructure, mechanical properties and fatigue crack growth behavior of friction stir welded joint of 6061-T6 aluminum alloy","volume":"135","author":"Zhang","year":"2020","journal-title":"Int. J. Fatigue"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"962","DOI":"10.1016\/j.matdes.2013.07.098","article-title":"A novel method for improving fatigue life of friction stir spot welded joints using localized plasticity","volume":"53","author":"Hassanifard","year":"2014","journal-title":"Mater. Des."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1016\/j.matdes.2015.04.012","article-title":"Numerical modeling for the effect of pin profiles on thermal and material flow characteristics in friction stir welding","volume":"77","author":"Su","year":"2015","journal-title":"Mater. Des."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"452","DOI":"10.1016\/j.jmatprotec.2017.06.039","article-title":"Keyhole refilled friction stir spot welding of aluminum alloy to advanced high strength steel","volume":"249","author":"Chen","year":"2017","journal-title":"J. Mater. Proc. Technol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.matdes.2017.03.063","article-title":"Effect of a Zn interlayer on dissimilar FSSW of Al and Cu","volume":"124","author":"Boucherit","year":"2017","journal-title":"Mater. Des."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1016\/j.matdes.2016.01.047","article-title":"Interfacial microstructure and properties of aluminum\u2013magnesium AZ31B multi-pass friction stir processed composite plate","volume":"94","author":"Zhao","year":"2016","journal-title":"Mater. Des."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/13\/19\/4247\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:13:02Z","timestamp":1760177582000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/13\/19\/4247"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,9,23]]},"references-count":39,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2020,10]]}},"alternative-id":["ma13194247"],"URL":"https:\/\/doi.org\/10.3390\/ma13194247","relation":{},"ISSN":["1996-1944"],"issn-type":[{"type":"electronic","value":"1996-1944"}],"subject":[],"published":{"date-parts":[[2020,9,23]]}}}