• Journal of Welding and Joining
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• 제18권3호
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• pp.97-105
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• 2000

The stress corrosion cracking(SCC) and hydrogen embrittlement cracking(HEC) characteristics of a weathering steel weldment were investigated in aerated acid-chloride solution. The electrochemical properties of weldment were investigated by polarization test and galvanic corrosion test. Weathering steel did not show passive behavior in the acid-chloride solution. Galvanic corrosion between the weld metal and the base metal was not observed because the base metal was anodic to the weld metal. The slow-strain-rate tests(SSRT0 were conducted at a constant strain rate o 7.87×{TEX}$10^{-7}${/TEX}/s at corrosion potential, and at potentiostatically controlled anodic and cathodic potentials. The weldment of weathering steel was susceptible to both anodic dissolution SCC and hydrogen evolution HEC.

• 소성∙가공
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• 제33권3호
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• pp.185-192
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• 2024

This study examined how varying tempering temperatures affect the susceptibility of Cr-Mo low alloy steels to hydrogen embrittlement. A slow strain-rate test (SSRT) was carried out on the steels electrochemically pre-charged with hydrogen in order to examine the hydrogen embrittlement behavior. The results showed that the hydrogen embrittlement resistance of the Cr-Mo low alloy steels improved with increasing tempering temperature. Thermal desorption analysis (TDA) revealed that diffusible hydrogen content decreased with increasing tempering temperature, accompanied by a slight increase in the peak temperature. This decrease in hydrogen content was likely due to a reduction in dislocation density which served as reversible hydrogen trap sites. These findings underline the significant role of tempering temperature in enhancing the hydrogen embrittlement resistance of Cr-Mo low alloy steels.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.154-159
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• 1998

In order to assess the susceptibility of the environmentally assisted cracking(EAC) on SA508 Cl.3 steel in primary water condition, potential step test and slow strain rate test(SSRT) were conducted in a simulated crack tip condition. In this test, anodic dissolution was dominant in the crack tip environments. Proposed simple dissolution model is a modification of Hishida's anodic dissolution model at the plastic zone. One can predict actual crack growth rate with the smooth specimen through this model.

• 한국표면공학회지
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• 제27권4호
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• pp.215-222
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• 1994

The role dispersoids has been studied in a number of researches as a key point for the high strength application of dispersion strengthened aluminum alloy. The mechanical alloying(MA) process with high mechanical properties of dispersion strengthened MA Al-8Ti-1B alloys were invested in order to evaluate their stress corrosion cracking(SCC) application. SCC properties of the mechanically alloyed Al-8Ti-1B were studied using slow strain rate test(SSRT). In this study Al-8Ti-1B alloy were more susceptible to SCC in solutions of pH=2.01 and 13.2 than pH=6.81 solution. In this study Al-8Ti-1B alloys by MA had more SCC resistance than Al-8Ti alloys or Al 7075-T73 alloys. So Al-8Ti-1B alloys by MA had more resistance in SSRT SCC susceptinility test than any other above alloying metals.

• Corrosion Science and Technology
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• 제18권6호
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• pp.267-276
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• 2019

The purpose of this study was to examine the influence of conditions for quenching and/or tempering on the corrosion and hydrogen diffusion behavior of ultra-strong automotive steel in terms of the localized plastic strain related to the dislocation density, and the precipitation of iron carbide. In this study, a range of analytical and experimental methods were deployed, such as field emission-scanning electron microscopy, electron back scatter diffraction, electrochemical permeation technique, slow-strain rate test (SSRT), and electrochemical polarization test. The results showed that the hydrogen diffusion parameters involving the diffusion kinetics and hydrogen solubility, obtained from the permeation experiment, could not be directly indicative of the resistance to hydrogen embrittlement (HE) occurring under the condition with low hydrogen concentration. The SSRT results showed that the partitioning process, leading to decrease in localized plastic strain and dislocation density in the sample, results in a high resistance to HE-induced by aqueous corrosion. Conversely, coarse iron carbide, precipitated during heat treatment, weakened the long-term corrosion resistance. This can also be a controlling factor for the development of ultra-strong steel with superior corrosion and HE resistance.

• Corrosion Science and Technology
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• 제15권5호
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• pp.237-244
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• 2016

2205 duplex stainless steels have been used for the construction of the marine environment, because of their excellent corrosion resistance and high strength. However, the resistance to hydrogen embrittlement (HE) may be less than that of 316L austenitic stainless steel. The reason why 316L stainless steels have better resistance to HE is associated with crystal structure (FCC, face centered cubic) and the higher stacking faults energy than 2205 duplex stainless steels. Furthermore 2205 stainless steels with or without tungsten were also examined in terms of HE. 2205 stainless steels containing tungsten is less resistible to HE. It is because dislocation tangle was formed in 2205 duplex stainless steels. Slow strain-rate tensile test (SSRT) was conducted to measure the resistance to HE under the cathodic applied potential. Hydrogen embrittlement index (HEI) was used to evaluate HE resistance through the quantitative calculation.

• 한국주조공학회지
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• 제40권5호
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• pp.129-133
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• 2020

The outcomes of solution annealing and stress corrosion cracking in cold-worked 316L austenitic stainless steel have been studied using x-ray diffraction (XRD) and the slow strain rate test (SSRT) technique. The good compatibility with a high-temperature water environment allows 316L austenitic stainless steel to be widely adopted as an internal structural material in light water reactors. However, stress corrosion cracking (SCC) has recently been highlighted in the stainless steels used in commercial pressurized water reactor (PWR) plants. In this paper, SCC and inter granular cracking (IGC) are discussed on the basis of solution annealing in a chloride environment. It was found that the martensitic contents of cold-worked 316L stainless steel decreased as the solution annealing time was increased at a high temperature. Moreover, mode of SCC was closely related to use of a chloride environment. The results here provide evidence of the vital role of a chloride environment during the SCC of cold-worked 316L.

• 한국재료학회지
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• 제32권11호
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• pp.466-473
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• 2022

The effect of Cr and Mo contents on the hydrogen embrittlement of tempered martensitic steels was investigated in this study. After the steels with different Cr and Mo contents were austenitized at 820 ℃ for 90 min, they were tempered at 630 ℃ for 120 min. The steels were composed of fully tempered martensite with a lath-type microstructure, but the characteristics of the carbides were dependent on the Cr and Mo contents. As the Cr and Mo contents increased, the volume fraction of film-like cementite and prior austenite grain size decreased. After hydrogen was introduced into tensile specimens by electrochemical charging, a slow strain-rate test (SSRT) was conducted to investigate hydrogen embrittlement behavior. The SSRT results revealed that the steel with lower Cr or lower Mo content showed relatively poor hydrogen embrittlement resistance. The hydrogen embrittlement resistance of the tempered martensitic steels increased with increasing Mo content, because the reduction in the film-like cementite and prior austenite grain size plays an important role in improving hydrogen embrittlement resistance. The results indicate that controlling the Cr and Mo contents is essential to achieving a tempered martensitic steel with a combination of high strength and excellent hydrogen embrittlement resistance.

• Journal of Welding and Joining
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• 제19권1호
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• pp.65-74
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• 2001

A study on the corrosion behavior in case of As-welded and PWHT temperature 55$0^{\circ}C$ of welding part of RE36 steel for marine structure was investigated with parameters such as micro-Vickers hardness, corrosion potential measurement of weld metal(WM), base metal(BM) and heat affected zone(HAZ), both Al anode generating current and Al anode weight loss quantity under sacrificial anode cathodic protection conditions. And also we carried out slow strain rate test(SSRT) in order to research both limiting cathodic polarization potential for hydrogen embrittlement and optimum cathodic protection potential as well as mechanical properties by post-weld heat treatment(PWHT) effect. Hardness of HAZ was the highest among three parts(WM, BM and HAZ) and the highest galvanic corrosion susceptibility was HAZ. And the optimum cathodic polarization potential showing the best mechanical properties by SSRT method was from -770mV to -875mV(SCE). In analysis of SEM fractography, applied cathodic potential from -770mV to -875mV(SCE) it appeared dimple pattern with ductile fracture while it showed transgranular pattern (Q. C : quasicleavage) under -900mV(SCE). However it is suggested that limiting cathodic polarization potential indicating hydrogen embrittlement was under -900mV(SCE).

• 한국표면공학회지
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• 제40권6호
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• pp.262-270
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• 2007

Recently, there has been a new appreciation of aluminum alloys as materials that are capable of reducing the environment load. This is because aluminum alloys are lightweight, easy to recycle, permit miniaturization, and have environmental friendly properties. In this study, we investigated the mechanical and electrochemical properties of 5083F aluminum alloys using slow strain rate test(SSRT) and potentiostatic tests under various potential conditions. In the potentiostatic tests, the current density in the potential range from -0.7 to -1.4V after 1,200 s was low. After considering the results of the potentiostatic tests, maximum tensile strength, yield strength, elongation, time-to-fracture, observation of fractured specimen and fractography analysis, the optimum protection potential range was between -1.3 and -0.7V(Ag/AgCl).