scholarly journals Analysis of Stress Corrosion Cracking Propagation of SS304 Stainless Steel Using Crack Shape and Etch Pits

2020 ◽  
Vol 58 (9) ◽  
pp. 583-589
Author(s):  
Byung Hak Choe ◽  
Sang Woo Lee ◽  
Jong Kee Ahn ◽  
Jinhee Lee
Keyword(s):  
Stainless Steel ◽  
Phase Transformation ◽  
Hydrogen Embrittlement ◽  
Crack Propagation ◽  
Stress Corrosion ◽  
High Hardness ◽  
Face Centered Cubic ◽  
High Concentration ◽  
Etch Pits ◽  
Tem Analysis

Austenitic stainless steel SS304 is vulnerable to Cl atmosphere SCC (stress corrosion crack). In this study, SCC phenomena related to stress and corrosion composition were analyzed to identify the mechanism for SCC initiation and propagation in SS304. The microstructure and mechanical properties resulting from crack propagation were analyzed by OM, SEM/EDS and micro Vickers hardness tests. The abnormal phase transformation induced by the SCC was analyzed by TEM and diffraction. As a result of these analyses, the shape of SCC was observed to form a branched type crack, which was related to etch pit patterns on the etched surface due to the austenitic fcc (face centered cubic) lattice slip. In addition, the high concentration accumulation of Cl and S components at the SCC site, observed by SEM/EDS, indicated that the SCC was affected by the corrosive atmosphere. The SCC crack propagation was accompanied by hardening, which is believed to be associated with the mechanism of hydrogen embrittlement. High resolution TEM analysis found abnormal satellite diffraction points in the SCC high hardness region. This means that a superlattice phase with high hardness values is formed near the SCC region. And the HIC (hydrogen induced crack) effect, a kind of hydrogen embrittlement, was also influenced by the hardened superlattice phase. It is assumed that the SCC and HIC are similar phenomena produced in the same stress and corrosive atmosphere by superlattice phase transformation.

Stress corrosion property of 304 stainless steel and Q345 steel laser-MAG hybrid welded joints

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040057
Author(s):  
Hang Lv ◽  
Guoqing Gou ◽  
Zhenghong Fu ◽  
Wei Gao
Keyword(s):  
Stainless Steel ◽  
Crack Propagation ◽  
Stress Corrosion ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Corrosion Property ◽  
304 Stainless Steel ◽  
Propagation Path ◽  
Crack Propagation Path ◽  
Immersion Testing

The stress corrosion cracking (SCC) property of laser-MAG hybrid welded 304 stainless steel and Q345 steel was evaluated through cycle-immersion testing in 3.5 wt.% NaCl solution. The average SCC crack propagation rate of different zones under different initial stress intensity factors was calculated, and the SCC fracture and crack propagation path were observed. The microstructure and mechanical properties of the weld joint have also been examined. The result indicates that the fusion zone (FZ) is extremely prone to SCC. The average SCC crack propagation rate in FZ is [Formula: see text] mm/h, while no obvious SCC was found in the base metal (BM) and heat-affected zone (HAZ). The steel BM and HAZ may also suffer SCC, but not as fast as in FZ. Grooves caused by SCC were found on the fracture surface with a large amount of corrosion products accumulated close to the interface between the pre-crack section and SCC section. Crystallized-sugar-shaped pattern was found on the SCC zone of FZ. Crack jumping, deflection and crack closure occurred in the crack propagation path. Martensite on the FZ was considered to be the major reason that the FZ has a higher SCC propagation rate.

Experimental Study on Crack Growth Behavior for Austenitic Stainless Steel in High Temperature Pure Water

1986 ◽  
Vol 108 (2) ◽  
pp. 226-233 ◽  
Author(s):  
M. Hishida ◽  
M. Saito ◽  
K. Hasegawa ◽  
K. Enomoto ◽  
Y. Matsuo
Keyword(s):  
Stainless Steel ◽  
Crack Propagation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Surface Crack ◽  
Stress Ratio ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Surface Crack Growth

Crack growth behavior of Type 304 stainless steel in a simulated BWR water environment was investigated for the quantitative characterization of subcritical flaw growth in BWR piping systems. Crack propagation rates under corrosion fatigue and stress corrosion cracking were generated using compact specimens. The effects of several parameters on the rates were discussed. Furthermore, surface crack growth behavior was examined under different modes of cyclic loading, and results were discussed in comparison with compact specimen data. The corrosion fatigue crack propagation rates strongly depended on the frequency and the stress ratio. The rates became higher as the frequency lowered and the stress ratio increased. No effect from dissolved oxygen concentration and heat treatment of the steel was observed in tests, where transgranular cracking mainly took place. Stress corrosion cracking rate data indicated KISCC was above 15 MPa•m1/2. On the other hand, surface crack growth behavior included scattered crack propagation rates. However, the relationship between da/dN and ΔK was basically similar to that obtained in the compact specimens, except under given test conditions, where the acceleration for the crack growth rate at a crack tip on the panel surface was different from that at the deepest point.

Stress Corrosion and Hydrogen Cracking off 17-7 Stainless Steel

CORROSION ◽  
1966 ◽  
Vol 22 (1) ◽  
pp. 23-27 ◽  
Author(s):  
I. MATSUSHIMA ◽  
D. DEEGAN ◽  
H. H. UHLIG
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Face Centered Cubic ◽  
Hydrogen Cracking ◽  
Pure Phase ◽  
Face Centered ◽  
As Stress ◽  
Mgcl2 Solution

Abstract Whether a stainless steel fails by stress corrosion cracking or by hydrogen cracking depends on its structure. A pure ferritic 18–8, body-centered cubic as quenched, fails by hydrogen cracking when cathodically polarized in dilute sulfuric acid containing arsenic trioxide. However, it is resistant to stress corrosion cracking in MgCl2 solution boiling at 154 C (310 F). A similar composition austenitic 18–8, face-centered cubic as quenched and tested similarly is resistant to hydrogen cracking but fails by stress corrosion cracking. Type 301 austenitic 17–7 stainless steel, which transforms in part to ferrite on cold rolling, is resistant, therefore, to hydrogen cracking as annealed-quenched or slightly cold reduced. It fails within 10–30 minutes when cold reduced more than 20 percent even though it transforms only partially to ferrite. In MgCl2 solution, both the annealed-quenched and the cold-reduced alloy fail, cracking times being prolonged by cathodic polarization, characterizing the failures as stress corrosion cracking. Contrary to reactions observed in pure phase alloys, stainless steels containing mixtures of austenite and ferrite may fail either by hydrogen cracking or by stress corrosion cracking, depending on the environment.

Using Radioactive Tracers to Study Chloride Stress Corrosion Cracking of Stainless Steels

CORROSION ◽  
1966 ◽  
Vol 22 (2) ◽  
pp. 48-52 ◽  
Author(s):  
R. F. OVERMAN
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Radioactive Tracer ◽  
Corrosion Cracking ◽  
Radioactive Tracers ◽  
Surface Cracks ◽  
High Concentration ◽  
Chloride Stress Corrosion Cracking

Abstract A combination of radioactive tracer and metallurgical techniques has made it possible to study some of the conditions necessary to produce chloride stress corrosion cracks in stainless steel The existence of charged areas on the surface of steel was demonstrated by autoradiography of samples exposed to solutions containing radioactive tracers. Charged areas on the surface may be created by a high concentration of small sulfide inclusions; the cracks that appeared were initiated within these charged areas. Seven nanograms of chloride on one charged area was sufficient to start corrosion and subsequent surface cracks in a surface of steel stressed by grinding.

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