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Wpływ wodoru na pękanie spoin w stalach bainitycznych i mikrostopowych

Tasak E., Ziewiec A., Adamiec J.

Hutnik, Wiadomości Hutnicze

2008

Vol. 75, nr 4

170-176

W pracy przeprowadzono analizę charakteru pękania spoin w stalach mikroskopowych oraz stalach bainitycznych niskostopowych. Ustalono, że wodór wywołuje również powstawanie pęknięć gorących w procesie krzepnięcia spoin. Przeprowadzone badania pozwoliły opracować mechanizm pękania spoin na gorąco oraz dalszego ich rozwoju jako pęknięć zimnych zwłocznych. Zweryfikowano również opisywany w literaturze mechanizm powstawania pęknięć typu "chewron" wykazując, że początkiem pęknięć zimnych "chewron" są pęknięcia gorące.

The present work shows analysis of the cracking characteristics in the microalloyed steels and the bainitic low alloyed steels. It was established that hydrogen causes also hot cracks during solidification of the welded joints. The studies allowed elaboration of the mechanism of hot cracking for the welded joints and the mechanism of their further development as delayed cold cracks. The paper verifies the mechanism of "chewron " cracks starting developed in the reference showing that the beginning of the "chewron " cracks are hot cracks.

Evaluation of susceptibility of high-strength steels to hydrogen delayed cracking

Świeczko-Żurek B., Sobieszczyk S., Ćwiek J., Zieliński A.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 18, nr 1-2

243--246

Purpose: Purpose of this paper is evaluation of susceptibility of high-strength structural steels to hydrogen delayed cracking. Design/methodology/approach: Susceptibility to hydrogen delayed cracking of high-strength alloy steels have been made under constant load in hydrogen generating environments. Test were carried out using round notched specimens subjected to axial tensile load being equivalence to 75-96% of maximum force obtained from a tensile tests in air. Two constructional middle carbon steel - grades 26H2MF and 34HNM were tested in used (worn out) mineral engine oil at temperature of 80°C. One low carbon weldable steel grade - 14HNMBCu was investigated in sea-water under cathodic polarization at room temperature. Presence or lack of cracking within 200 hours was chosen as a measure of susceptibility to hydrogen delayed cracking. Fracture modes of failed samples were examined with the use of scanning electron microscope. Findings: All tested steels reveal high resistance to hydrogen degradation under constant load. Hydrogen delayed cracking does not occur until the load level is as high as flow stress (yield strength). Research limitations/implications: Further research should be taken to reveal the exact mechanism of crack initiation. Practical implications: Tested steels could be safely utilized within elastic range of stress in hydrogen generating environments. Originality/value: Under the critical load and hydrogen concentration notched samples premature failed and hydrogen-enhanced localised plasticity (HELP) model is a viable degradation mechanism.

Hydrogen delayed cracking of high-strength weldable steels

Ćwiek J.

Advances in Materials Science

2005

Vol. 5, nr 1-3

5-13

Hydrogen degradation of high-strength steel and their welded joints was evaluated under constant load mode in sea-water. Tests were carried out using round notched specimens in sea-water at open circuit potential and under cathodic polarization. 14HNMBCu steel grade with minimum yield strength of 690 MPa, and their submerged arc welded (SAW) and shielded metal arc welded (SMAW) joints were examined. Presence or lack of delayed failure of samples was chosen as measures of hydrogen degradation. Fracture modes were investigated with the use of a scanning electron microscope (SEM).