Stabilization of austenite in low carbon Cr–Mo steel by high speed deformation during friction stir welding.
- Resource Type
- Article
- Authors
- Miura, Takuya; Ueji, Rintaro; Fujii, Hidetoshi; Komine, Hisanao; Yanagimoto, Jun
- Source
- Materials & Design. Jan2016, Vol. 90, p915-921. 7p.
- Subject
- *FRICTION stir welding
*AUSTENITE
*HEAT resistant steel
*MARTENSITE
*MARTENSITIC stainless steel
- Language
- ISSN
- 0264-1275
Friction stir welding (FSW) was applied to a low carbon alloyed steel in order to stabilize the austenite phase which can effectively maintain a preferable toughness. A Cr–Mo steel sheet (0.20 wt.%C–1.07%Cr–0.16%Mo–0.24%Si–0.61%Mn–bal. Fe) with a ferrite pearlite structure was friction stir welded under the conditions in which the sample was reheated above the A 3 temperature at the maximum. The microstructure observations in the stir zone clarified martensite with several area fractions of retained austenite and elongated ferrite. The retained austenite provides a high ductility with a high strength in the stir zone. In order to clarify the formation mechanism of the austenite, compression tests were conducted at various strain rates up to 10/s using an ultrahigh-speed compression testing machine. When the sample was compressed at the high strain rate, the elongated ferrite grains and retained austenite were formed. This microstructure was similar to the microstructure in the FSW stir zone, suggesting that the efficient accumulation of plastic strain in the austenite during the FSW plays an important role in obtaining the retained austenite. [ABSTRACT FROM AUTHOR]