Ultrasonic imaging in coarse-grained stainless steels by total focusing method

2016 ◽  
Author(s):  
E. Lopez Villaverde ◽  
S. Robert ◽  
C. Prada
Keyword(s):  
Stainless Steels ◽  
Ultrasonic Imaging ◽  
Coarse Grained

Ultrasonic imaging of defects in coarse-grained steels with the decomposition of the time reversal operator

2016 ◽  
Vol 140 (1) ◽  
pp. 541-550 ◽  
Author(s):  
Eduardo Lopez Villaverde ◽  
Sébastien Robert ◽  
Claire Prada
Keyword(s):  
Time Reversal ◽  
Ultrasonic Imaging ◽  
Coarse Grained

Hydrogen Embrittlement of Ultrafine-Grained Austenitic Stainless Steels

2018 ◽  
Vol 54 (1) ◽  
pp. 25-45 ◽  
Author(s):  
E. G. Astafurova ◽  
S. V. Astafurov ◽  
G. G. Maier ◽  
V. A. Moskvina ◽  
E. V. Melnikov ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Hydrogen Embrittlement ◽  
Stainless Steels ◽  
Subgrain Size ◽  
Austenitic Stainless Steels ◽  
Mechanical Twinning ◽  
Coarse Grained ◽  
Flow Strength ◽  
Hydrogen Charging ◽  
Ultrafine Grained

Abstract The effect of electrochemical hydrogen-charging on tensile properties, mechanisms of plastic deformation and fracture micromechanisms was studied using two ultrafine-grained (UFG) Cr-Ni austenitic stainless steels. UFG austenitic structures with an average subgrain size of 200 nm for CrNiMo (316L-type) and 520 nm for CrNiTi (321-type) steel were produced using hot-to-warm ABC-pressing. Hydrogen-charging up to 100 hours weakly influences stages of plastic flow, strength properties and elongation of the UFG steels. TEM analysis testifies to hydrogen-assisted partial annihilation and rearrangement of dislocations into dislocation tangles, and to hydrogen-induced variation in ratio of low- and high-angle misorientations in UFG structure of both steels. Hydrogen-alloying promotes mechanical twinning and deformation-induced γ ® e martensitic transformation in the UFG steels under tension. Ultrafine-grained CrNiTi steel with lower stacking fault energy (SFE) is more susceptible to mechanical twinning and deformation-induced γ ® e martensitic transformation in comparison with CrNiMo steel with higher SFE. The micromechanism of the fracture in hydrogen-assisted surface layers of the steels is compositional, grain-size and hydrogen content dependent characteristic. The present results demonstrate that the steels with UFG structure possess higher resistance to hydrogen embrittlement compared to coarse-grained analogues.

Fatigue damage in coarse-grained lean duplex stainless steels

2016 ◽  
Vol 659 ◽  
pp. 47-54 ◽  
Author(s):  
R. Strubbia ◽  
S. Hereñú ◽  
M.C. Marinelli ◽  
I. Alvarez-Armas
Keyword(s):  
Fatigue Damage ◽  
Stainless Steels ◽  
Duplex Stainless Steels ◽  
Coarse Grained

scholarly journals Formation of residual stresses in austenitic stainless steels by infeed and recess rotary swaging

2020 ◽  
Author(s):  
Holger Hoche ◽  
Fabian Jaeger ◽  
Alessandro Franceschi ◽  
Matthias Oechsner ◽  
Peter Groche
Keyword(s):  
Residual Stresses ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Phase Changes ◽  
Austenitic Steels ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Forming Process ◽  
Cold Forming ◽  
Rotary Swaging

The austenitic stainless steels 1.4307 and 1.4404 significantly benefit from cold forming, due to their high work hardening capability. Great potential to improve the component's fatigue properties is expected by optimizing the forming process chain such that specific residual stresses are induced in critical component areas. In this work, an analysis of the formation of residual stresses during rotary swaging is carried out. Through this incremental forming process, high strain hardening and a complex material flow history are induced in the workpieces. Therefore, measuring strategies for the residual stress measurement of cold de-formed austenitic steels by X-Ray diffraction, using the sin2Ψ-method, were developed. Here, especially the 1.4307 is a challenging material due to cold forming induced martensite formation. Despite phase changes, both cold formed materials exhibit anisotropic microstructures as well as coarse grained areas. Moreover, particular notched geometries are produced on the workpieces by rotary swaging. The measuring techniques are further developed for these complex geometries and the residual stresses are investigated.

Fatigue behavior of ultrafine-grained and coarse-grained Cr–Ni austenitic stainless steels

2011 ◽  
Vol 528 (10-11) ◽  
pp. 3890-3896 ◽  
Author(s):  
A.S. Hamada ◽  
L.P. Karjalainen ◽  
P.K.C. Venkata Surya ◽  
R.D.K. Misra
Keyword(s):  
Stainless Steels ◽  
Fatigue Behavior ◽  
Austenitic Stainless Steels ◽  
Coarse Grained ◽  
Ultrafine Grained
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