scholarly journals Characterization of a Surface Hydrogen Charging Product Affecting the Mechanical Properties in 2205 Duplex Stainless Steel

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1682 ◽  
Author(s):  
Bo Kan ◽  
Zixuan Yang ◽  
Jinxu Li

When 2205 duplex stainless steel (DSS) is immersed in simulated seawater under high hydrostatic pressure, or in an electrochemically hydrogen charged state, a spindle-shaped product is found in the ferrite phase that seriously deteriorates the mechanical properties of 2205 DSS. This paper systematically studied the composition, structure, and properties of the hydrogen charging product. The results of a slow strain rate tensile test show that the hydrogen charging product evidently reduces the elongation of 2205 DSS, and microcracks mainly initiate at the interface between the hydrogen charging product and the ferrite matrix at either a low or a high strain rate. However, the elongation recovers to that of the hydrogen free sample after heating the sample at 300 °C for 0.5 h. The nano-hardness and reduced modules of the product are higher than those of the ferrite and austenite phases. An element analysis by energy dispersive spectroscopy (EDS) and secondary ion mass spectrometry (SIMS) indicates that the Ni and H contents in the hydrogen charging product are higher than in the normal ferrite area, and X-ray diffraction shows the characteristic peak of iron hydride at 40.07°. Moreover, a differential scanning calorimeter (DSC) test demonstrated that the phase decomposition temperature of the product is 268 °C, which coincides with the fact that it dissolves at a high temperature caused by the focused electron beam during transmission electron microscopy (TEM) analysis. All experimental results indicate that the hydrogen charging product is a hydride of FeH or (Fe, Ni)H.

2020 ◽  
Vol 34 (25) ◽  
pp. 2050269
Author(s):  
Yuqi Mao ◽  
Yuehong Zheng ◽  
Yu Shi ◽  
Min Zhu ◽  
Saitejin ◽  
...  

In order to further expand the application scope of 2205 duplex stainless steel (DSS), its microstructure and mechanical properties require as much attention as its corrosion properties. In this study, 2205DSSs were prepared by aluminothermic reaction and the microstructures and mechanical behavior of the rolled alloys were analyzed. The micro-nanocrystals composite structure appears in the alloys after rough rolling with deformation of 40% at [Formula: see text]C followed by finishing rolling with deformation of 30%, 50% and 70% at [Formula: see text]C. With the increase of rolling deformation, the two-phase structure is gradually elongated, the average size of the two-phase grains is gradually increased, and some [Formula: see text] phase will change to [Formula: see text] phase, the volume fraction of [Formula: see text] phase is gradually increased, and the distribution of nanocrystals is gradually uniform. Meanwhile, the fracture mode of alloy is gradually changed from ductile fracture to brittle fracture. The strength and hardness of the alloy increase gradually.


2015 ◽  
Vol 62 (3) ◽  
pp. 163-171 ◽  
Author(s):  
Yinhui Yang ◽  
Biao Yan

Purpose – The aim of this paper was to investigate the effect of strain rate on microstructure and corrosion behavior of 2205 duplex stainless steel, after high-temperature compression tests. Design/methodology/approach – The specimens were prepared using a Gleeble3800 thermo-simulation machine over a range of temperatures from 850 to 1,250°C and strain rates from 0.005 to 5 s−1, and the corresponding flow curves and deformation microstructure obtained were further analyzed. To evaluate the effect of strain rate on corrosion behavior, potentiodynamic polarization tests and double-loop electrochemical potentiodynamic reactivation (DL-EPR) were used to characterize the electrochemical performance. Findings – Compared with strain rate of 0.5 s−1, the worst corrosion resistance behavior from the potentiodynamic polarization test results after deformation at 0.005 s−1 was attributed to more austenite (γ) and ferrite (δ) grain boundaries or δ/γ phase interface formation due to the better effect of γ dynamic recrystallization (DRX) or δ dynamic recovery (DRV). Increasing strain rate to 5 s−1 lowered the corrosion resistance, due to the increase in dislocation density. At the low strain rate of 0.005 s−1, the susceptibility to intergranular corrosion (IGC) was comparatively high after deformation at 1050 and 1150°C with more γ/γ grains and δ/γ phase boundary formation, which was lowered with the strain rate increase to 0.5 s−1, due to suppressing effect of γ DRX. Originality/value – The paper provides the scientific basis for the practical application of hot working of 2205 duplex stainless steel.


2012 ◽  
Vol 503-504 ◽  
pp. 463-468 ◽  
Author(s):  
Xiao Liu ◽  
Long Mei Wang

The effects of rare earth metals on the inclusions and the mechanical properties of 2205 duplex stainless steel were studied by metallographic examination, scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of non-metallic inclusions in 2205 duplex stainless steel are changed, and rare earth metals played a very good role of modifying inclusions. The fracture mode of 2205 duplex stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding RE into the steel, and the spherical inclusions of rare earth oxysulfide in the dimple are the main factors for this transformation. The transverse impact toughness of 2205 duplex stainless steel is improved obviously by RE. In comparison with 2205 duplex stainless steel without RE, the transverse impact toughness of 2205 duplex stainless steel with RE is increased 20.49% at -40°C, and the room temperature strength are improved, the elongation and reduction of area have been improved 11.67%, 24.55% respectively.


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