A stress field parameter for weld hydrogen cracking

Dissertation

Risto Karppi

Research output: ThesisDissertationMonograph

Abstract

Hydrogen-induced cracking in the heat affected zone of steel weldments is studied with special reference to mechanical aspects.The stress field in the vicinity of the root of the root run butt weld and the notch of the Implant specimen is examined.A new parameter £1, analogical to the stress intensity factor, is defined and proposed as a stress controlling factor for weld hydrogen cracking.The effects of various geometric factors on ~ are analysed by defining a specimen severity parameter Fl and determining its values by finite element analysis.An approximate method is established for determining the value of the Fl parameter for real joints of three groove geometries: (i) single bevel, (ii) double Vee and (iii) Oblique y groove.The Fl parameter is applied to correlate various Implant test and Restraint test results.There two further parameters were employed: (i) remaining diffusible hydrogen content of weld metal at l OO° C, HK 100, and (ii) HAZ hardness (HV 1) .These were used to eliminate the difference between the tests in hydrogen level and microstructure, respectively.The results show the high potentiality of the three parameters: ~1, HRIOO and HV 1.Further, the results do strongly imply that the Implant test results can be applied to real structures in assessing the hydrogen cracking risk.The deep notch Implant specimen was found to have many advantages over the shallow and helical notch specimens in this respect.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Helsinki University of Technology
Publisher
Print ISBNs951-38-1536-6
Publication statusPublished - 1982
MoE publication typeG4 Doctoral dissertation (monograph)

Fingerprint

Welds
Hydrogen
Heat affected zone
Stress intensity factors
Hardness
Finite element method
Microstructure
Geometry
Steel
Metals

Cite this

Karppi, R. (1982). A stress field parameter for weld hydrogen cracking: Dissertation. VTT Technical Research Centre of Finland.
Karppi, Risto. / A stress field parameter for weld hydrogen cracking : Dissertation. VTT Technical Research Centre of Finland, 1982. 122 p.
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title = "A stress field parameter for weld hydrogen cracking: Dissertation",
abstract = "Hydrogen-induced cracking in the heat affected zone of steel weldments is studied with special reference to mechanical aspects.The stress field in the vicinity of the root of the root run butt weld and the notch of the Implant specimen is examined.A new parameter £1, analogical to the stress intensity factor, is defined and proposed as a stress controlling factor for weld hydrogen cracking.The effects of various geometric factors on ~ are analysed by defining a specimen severity parameter Fl and determining its values by finite element analysis.An approximate method is established for determining the value of the Fl parameter for real joints of three groove geometries: (i) single bevel, (ii) double Vee and (iii) Oblique y groove.The Fl parameter is applied to correlate various Implant test and Restraint test results.There two further parameters were employed: (i) remaining diffusible hydrogen content of weld metal at l OO° C, HK 100, and (ii) HAZ hardness (HV 1) .These were used to eliminate the difference between the tests in hydrogen level and microstructure, respectively.The results show the high potentiality of the three parameters: ~1, HRIOO and HV 1.Further, the results do strongly imply that the Implant test results can be applied to real structures in assessing the hydrogen cracking risk.The deep notch Implant specimen was found to have many advantages over the shallow and helical notch specimens in this respect.",
author = "Risto Karppi",
year = "1982",
language = "English",
isbn = "951-38-1536-6",
series = "Publications / Technical Research Centre of Finland",
publisher = "VTT Technical Research Centre of Finland",
number = "9",
address = "Finland",
school = "Helsinki University of Technology",

}

Karppi, R 1982, 'A stress field parameter for weld hydrogen cracking: Dissertation', Doctor Degree, Helsinki University of Technology.

A stress field parameter for weld hydrogen cracking : Dissertation. / Karppi, Risto.

VTT Technical Research Centre of Finland, 1982. 122 p.

Research output: ThesisDissertationMonograph

TY - THES

T1 - A stress field parameter for weld hydrogen cracking

T2 - Dissertation

AU - Karppi, Risto

PY - 1982

Y1 - 1982

N2 - Hydrogen-induced cracking in the heat affected zone of steel weldments is studied with special reference to mechanical aspects.The stress field in the vicinity of the root of the root run butt weld and the notch of the Implant specimen is examined.A new parameter £1, analogical to the stress intensity factor, is defined and proposed as a stress controlling factor for weld hydrogen cracking.The effects of various geometric factors on ~ are analysed by defining a specimen severity parameter Fl and determining its values by finite element analysis.An approximate method is established for determining the value of the Fl parameter for real joints of three groove geometries: (i) single bevel, (ii) double Vee and (iii) Oblique y groove.The Fl parameter is applied to correlate various Implant test and Restraint test results.There two further parameters were employed: (i) remaining diffusible hydrogen content of weld metal at l OO° C, HK 100, and (ii) HAZ hardness (HV 1) .These were used to eliminate the difference between the tests in hydrogen level and microstructure, respectively.The results show the high potentiality of the three parameters: ~1, HRIOO and HV 1.Further, the results do strongly imply that the Implant test results can be applied to real structures in assessing the hydrogen cracking risk.The deep notch Implant specimen was found to have many advantages over the shallow and helical notch specimens in this respect.

AB - Hydrogen-induced cracking in the heat affected zone of steel weldments is studied with special reference to mechanical aspects.The stress field in the vicinity of the root of the root run butt weld and the notch of the Implant specimen is examined.A new parameter £1, analogical to the stress intensity factor, is defined and proposed as a stress controlling factor for weld hydrogen cracking.The effects of various geometric factors on ~ are analysed by defining a specimen severity parameter Fl and determining its values by finite element analysis.An approximate method is established for determining the value of the Fl parameter for real joints of three groove geometries: (i) single bevel, (ii) double Vee and (iii) Oblique y groove.The Fl parameter is applied to correlate various Implant test and Restraint test results.There two further parameters were employed: (i) remaining diffusible hydrogen content of weld metal at l OO° C, HK 100, and (ii) HAZ hardness (HV 1) .These were used to eliminate the difference between the tests in hydrogen level and microstructure, respectively.The results show the high potentiality of the three parameters: ~1, HRIOO and HV 1.Further, the results do strongly imply that the Implant test results can be applied to real structures in assessing the hydrogen cracking risk.The deep notch Implant specimen was found to have many advantages over the shallow and helical notch specimens in this respect.

M3 - Dissertation

SN - 951-38-1536-6

T3 - Publications / Technical Research Centre of Finland

PB - VTT Technical Research Centre of Finland

ER -

Karppi R. A stress field parameter for weld hydrogen cracking: Dissertation. VTT Technical Research Centre of Finland, 1982. 122 p.