Micromechanical characterisation of weld metal susceptibility to hydrogen-assisted cold cracking using instrumented indentation
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- 作者：Rahim Kurji ; Olivier Lavigne ; Reza Ghomashchi
- 刊名：Welding in the World
- 出版年：2016
- 出版时间：September 2016
- 年：2016
- 卷：60
- 期：5
- 页码：883-897
- 全文大小：5,290 KB
- 刊物主题：Metallic Materials; Continuum Mechanics and Mechanics of Materials; Theoretical and Applied Mechanics;
- 出版者：Springer Berlin Heidelberg
- ISSN：1878-6669
- 卷排序：60
文摘
Hydrogen-assisted cold cracking is generally accepted to be the consequence of a critical concentration of hydrogen trapped within a susceptible microstructure and subjected to a threshold level of stress. Traditionally, hardness has been used as a proxy for establishing the critical limits above which the risk of a hydrogen crack propagating is considered significant. However, developments in the steel-making process, in particular thermomechanically controlled processing, has brought into question the suitability of empirical hardness limits developed using older generation steels. In this paper, a safe welding boundary was established for single-pass root runs for API 5 L X70 steel welded with E6010 electrodes. Across this boundary, it was shown that hydrogen cracks were present in welds with hardness’s well below the traditionally accepted threshold of 350 HV. This paper explores the use of nanoindentation as means of quantifying the susceptibility of welds deposited on high-strength low-alloy steels, using shielded metal arc welding, to hydrogen-assisted cold cracking. It is suggested that the use of the hardness/elastic modulus (H/E) ratio, which is directly related to the yield strength of a material, is a more suitable parameter to predict weld metal hydrogen-assisted cold cracking (HACC) susceptibility than is the hardness alone.Keywords (IIW Thesaurus)Pipeline steelsMMA weldingCold crackingHardnessElasticity