The Effect of Some Electrolytes on the Stress Corrosion Cracking of AISI 4340 Steel

CORROSION ◽  
1972 ◽  
Vol 28 (9) ◽  
pp. 340-344 ◽  
Author(s):  
H. R. BAKER ◽  
C. R. SINGLETERRY

Abstract The effects of solutions of 16 different electrolytes on the stress corrosion cracking (SCC) of AISI 4340 steel U-bend specimens have been studied at various concentrations and at 25, 65, and 100 C (77, 149, and 212 F). Stresses were near the yield point of the alloy. In unbuffered solutions of neutral salts, there was poor correlation between time to failure and the initial or final pH of the solution. In strongly buffered solutions, there was a strong pH dependence; the time to failure in 10% NaCl increased about 100 fold between pH 4–5 and pH 7. Susceptibility to cracking increased moderately with the concentration of KNO3 solutions, but decreased with rising concentration of NaCl solutions. The cracking rate increased by 50% per 10 C for NaCl solutions. The rate increased 85% per 10 C for KNO3 solutions. KNO2 or NaNO2, dicyclohexylammonium nitrate, some K2CrO4 solutions and all alkaline solutions with a strong reserve of base inhibited SCC by factors of 10 to 100 times as compared with cracking in distilled H2O.

CORROSION ◽  
1969 ◽  
Vol 25 (8) ◽  
pp. 342-344 ◽  
Author(s):  
A. TIRMAN ◽  
E. G. HANEY ◽  
PAUL FUGASSI

Abstract The resistance to stress corrosion cracking of AISI 4340 steel foil in 0.6M aqueous sodium chloride, acidified to pH 1.5 with hydrochloric acid, is greatly decreased by prior treatment of the specimens for short periods of time with aqueous and nonaqueous solutions of sulfur, organic and inorganic sulfides, sulfur dioxides, and the inorganic salts of sulfurousand sulfuric acids. It is suggested that this prior treatment produces sulfided areas which are inhibitors of the combination of atomic hydrogen into molecular hydrogen. The decreased resistance to stress corrosion cracking is thus attributed to hydrogen embrittlement. If the stress corrosion cracking test is made in 0.6M aqueous sodium chloride, adjusted to an initial pH of 8, the effect of a prior sulfiding treatment is small. The formation of such sulfided areas in practice result from the exposure of 4340 steels to industrial atmospheres which may contain hydrogen sulfide, sulfur dioxide, and elemental sulfur.


1991 ◽  
Vol 113 (1) ◽  
pp. 125-129 ◽  
Author(s):  
P. S. Pao ◽  
R. A. Bayles ◽  
G. R. Yoder

The presence of small ripple loading can, under certain circumstances, significantly reduce time-to-failure and threshold stress intensity for stress-corrosion cracking (SCC) of steels. A predictive framework for such ripple-loading effects (RLE) is developed from concepts and descriptors used in SCC and corrosion fatigue characterization. The proposed framework is capable of defining critical conditions required for the occurrence of RLE and predicting the time-to-failure curves. The agreement between the predicted and laboratory data is excellent.


Author(s):  
R Rajasekaran ◽  
AK Lakshminarayanan

The stress corrosion cracking (SCC) resistance of the laser beam welded (LBW) AISI 316LN austenitic stainless steel (SS) was assessed and compared to the base metal (BM). The weld joint was produced using a 2.5 kW laser power source at 1500 mm/min welding speed. Microstructural characterization of the base metal and weld joint were done by the following techniques: (i) Optical Microscopy (OM), (ii) Scanning Electron Microscopy (SEM) and (iii) Transmission Electron Microscopy (TEM). The primary mechanical properties such as strength, toughness and hardness of the welded joint were evaluated and compared with the base metal. Stress Corrosion Cracking (SCC) assessment was done in boiling 45 wt% MgCl2 solution at constant load condition as per American Society for Testing and Materials (ASTM) standard G36-94. From the SCC experiment data, steady-state elongation rate ([Formula: see text]), transition time ([Formula: see text]) and time to failure ([Formula: see text]) were found and generalized equations to predict the time to failure of the base metal and LBW joint were successfully derived. The passive film rupture mechanism majorly influenced the SCC failure for 316LN and welded joint. The formation of the discontinuous δ-ferrite network, residual stress and nitrogen pore nucleation at the fusion zone of the LBW joint deteriorated the SCC resistance. The metallographic and fractographic studies revealed brittle transgranular SCC failure of the base metal as well as the LBW joint in all the stress conditions.


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