Effect of friction stir welding speed on the microstructure and mechanical properties of a duplex stainless steel

Kang

et al. 2015

Metals

Experimental studies in various aspects have to be conducted to maintain stable applications of super duplex stainless steels (SDSS) because the occurrence rate of sigma phase, variable temperature and growth direction of sigma phase can influence mechanical performances of SDSS. Tensile tests of precipitated SDSS were performed under various temperatures to analyze mechanical and morphological behavior.

Section: Introductionmentioning

confidence: 99%

Low-Temperature Mechanical Behavior of Super Duplex Stainless Steel with Sigma Precipitation

Kang

et al. 2015

Metals

“…Some studies have been undertaken using FSW of DSS or SDSS 22,49 , but few data are available concerning root penetration. In this study, consolidated welded joints with full penetration were produced by FSW.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Friction stir welding of duplex and superduplex stainless steels and some aspects of microstructural characterization and mechanical performance

et al. 2016

Friction stir welding was used to produce butt joints on 6 mm thick plates of UNS S32101 lean duplex stainless steel, S32205 duplex stainless steel, and S32750 and S32760 superduplex stainless steels. Fully consolidated joints were achieved, with full penetration, using heat input of 1.37-1.50 kJ/mm. Specimens submitted to tensile testing performed perpendicular to the welding direction showed failure on the base metal, reflecting better mechanical performance of the welded joints. Furthermore, tensile testing along the joints revealed higher yield and tensile strengths in all cases, as well as increased elongation. Microstructural evaluation showed that there was pronounced grain refinement in the welded joints of all the materials studied, achieving grain sizes as small as 1 µm. The differences in the ferrite and austenite grain sizes in the stir zone, such as the degree of grain refinement, could be explained by the combination of dynamic recrystallization of austenite during the welding process and the recrystallization and growth of the ferrite grains, promoted firstly by the severe deformation and secondly by the high temperature inherent to the FSW process. Superduplex stainless steel FSW joints were more able to maintain a balanced microstructure, compared to conventional and lean duplex stainless steels, due to greater homogeneity of recrystallization in the welded joint.

“…Dentre elas, pode-se ressaltar a união no estado sólido excluindo os problemas decorrentes da solidificação. Adicionalmente, a microestrutura favorável tem sido mantida durante o processo de SAPNC e a precipitação de fases deletérias não tem sido observada [26][27][28]. Poucos trabalhos têm estudado processo de soldagem por atrito de aços inoxidáveis duplex com especial atenção à penetração completa.…”

Section: Soldagem De Aços Inoxidáveis Duplexunclassified

“…No estudo realizado por Steel et al [29] a penetração total não foi alcançada e os autores concentraram--se no estudo da metalurgia inerente ao processo. Outros traba-lhos [26,27] não indicaram se a penetração total foi alcançada. A falta de penetração completa deixa uma superfície livre próxima à raiz que faz o papel de um entalhe no material favorecendo o rompimento do mesmo naquela região.…”

Section: Soldagem De Aços Inoxidáveis Duplexunclassified

Desenvolvimento de sistema de apoio com depósito cerâmico para soldagem e processamento por atrito com pino não consumível

Santos

Hermengildo³

et al. 2014

Soldag. insp.

Resumo Palavras-chave: Soldagem e processamento por atrito com pino não consumível; mesa de apoio; penetração total. Abstract:Usually, the workpiece is deformed during the friction stir welding, due to high applied loads. Consequently, fully and consolidated friction stir welded joints as well as tools life time can be affected promoting unscheduled manufacturing stops which favorites decreasing the welding productivity. Furthermore, the workforce is dislocated to not predicted maintenance steps. This work proposes the development of a special ceramic backing to joining and processing material using FSW technologies. Four ceramic deposits were tested over a steel plate , which allowed selecting those with less porosity and, thus, better strength. This backing allowed to obtain full penetration welds for duplex stainless steels, to resist high forces during engage for high strength low alloy steels and to obtain consolidated aluminum-steel dissimilar joints. For the last one, there was not adherence of the soft material in workpiece. In addition, the ceramic backing allowed confine the heat and plasticized metal, as well as developing established welding parameters.