Performance of TMCP steel with respect to mechanical properties after cold forming and post-forming heat treatment

David Porter (Corresponding Author), Anssi Laukkanen, Pekka Nevasmaa, Klaus Rahka, Kim Wallin

Research output: Contribution to journalArticleScientificpeer-review

19 Citations (Scopus)

Abstract

The paper describes the results of work done in the Finnish part of the ECOPRESS project on the mechanical properties of pressure vessels made from the TMCP steel grade P420ML2. Dished end (DE)-cylinder assemblies with diameters of 2500 mm and thicknesses of 15 and 30 mm have been examined using DE in both the cold-formed (CF) and CF and post-forming heat treated conditions. The blanks for the DEs contained welds to enable the effect of cold forming on weld metal to be evaluated.

Cold forming increases both the transition temperature and the strength of the DEs. Nevertheless, toughness against brittle fracture in the CF state is good for all parts of the DEs and girth weld with T27J<−50 °C in the absence of blank welds and <−20 °C when blank welds are present. For PFHT DEs T27J<−50 °C even for the blank welds. T27J was found to correlate with the fracture toughness reference temperature T0 which can be used to determine the minimum operating temperature. The impact toughness of the CF DE can be determined by compressing plate specimens 15% and ageing 30 min at 250 °C. Such a procedure can form the basis for an additional requirement on PxxxM/ML grades when high cold forming strains are involved in vessel manufacture. Ductile fracture is not of concern, as upper shelf toughness remains high in all parts of the DE.

The yield and tensile strengths of a CF DE are much greater than those of the cylinder, whereas the membrane stresses on the cylinder are greater than those on the DE. Consequently, design can be safely based on the properties of the nominally unformed cylinder. Furthermore, tensile instability will be first reached in the cylinder before it is reached in the DE, even though Y/T is at its lowest in the cylinder. Secondary bending stresses are greatest at the DE knuckle, but the CF DE has more than sufficient ductility in bending to accommodate the bending strain. The high Y/T of CF DE is combined with high material ductility and is therefore fully acceptable.

Original languageEnglish
Pages (from-to)867 - 877
Number of pages11
JournalInternational Journal of Pressure Vessels and Piping
Volume81
Issue number10-11
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

Fingerprint

Steel
Welds
Heat treatment
Mechanical properties
Toughness
Ductility
Fracture toughness
Ductile fracture
Brittle fracture
Pressure vessels
Superconducting transition temperature
Yield stress
Tensile strength
Aging of materials
Metals
Membranes
Temperature

Keywords

  • dished ends
  • cold forming
  • heat treatment
  • ProperTune

Cite this

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title = "Performance of TMCP steel with respect to mechanical properties after cold forming and post-forming heat treatment",
abstract = "The paper describes the results of work done in the Finnish part of the ECOPRESS project on the mechanical properties of pressure vessels made from the TMCP steel grade P420ML2. Dished end (DE)-cylinder assemblies with diameters of 2500 mm and thicknesses of 15 and 30 mm have been examined using DE in both the cold-formed (CF) and CF and post-forming heat treated conditions. The blanks for the DEs contained welds to enable the effect of cold forming on weld metal to be evaluated.Cold forming increases both the transition temperature and the strength of the DEs. Nevertheless, toughness against brittle fracture in the CF state is good for all parts of the DEs and girth weld with T27J<−50 °C in the absence of blank welds and <−20 °C when blank welds are present. For PFHT DEs T27J<−50 °C even for the blank welds. T27J was found to correlate with the fracture toughness reference temperature T0 which can be used to determine the minimum operating temperature. The impact toughness of the CF DE can be determined by compressing plate specimens 15{\%} and ageing 30 min at 250 °C. Such a procedure can form the basis for an additional requirement on PxxxM/ML grades when high cold forming strains are involved in vessel manufacture. Ductile fracture is not of concern, as upper shelf toughness remains high in all parts of the DE.The yield and tensile strengths of a CF DE are much greater than those of the cylinder, whereas the membrane stresses on the cylinder are greater than those on the DE. Consequently, design can be safely based on the properties of the nominally unformed cylinder. Furthermore, tensile instability will be first reached in the cylinder before it is reached in the DE, even though Y/T is at its lowest in the cylinder. Secondary bending stresses are greatest at the DE knuckle, but the CF DE has more than sufficient ductility in bending to accommodate the bending strain. The high Y/T of CF DE is combined with high material ductility and is therefore fully acceptable.",
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Performance of TMCP steel with respect to mechanical properties after cold forming and post-forming heat treatment. / Porter, David (Corresponding Author); Laukkanen, Anssi; Nevasmaa, Pekka; Rahka, Klaus; Wallin, Kim.

In: International Journal of Pressure Vessels and Piping, Vol. 81, No. 10-11, 2004, p. 867 - 877.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Performance of TMCP steel with respect to mechanical properties after cold forming and post-forming heat treatment

AU - Porter, David

AU - Laukkanen, Anssi

AU - Nevasmaa, Pekka

AU - Rahka, Klaus

AU - Wallin, Kim

PY - 2004

Y1 - 2004

N2 - The paper describes the results of work done in the Finnish part of the ECOPRESS project on the mechanical properties of pressure vessels made from the TMCP steel grade P420ML2. Dished end (DE)-cylinder assemblies with diameters of 2500 mm and thicknesses of 15 and 30 mm have been examined using DE in both the cold-formed (CF) and CF and post-forming heat treated conditions. The blanks for the DEs contained welds to enable the effect of cold forming on weld metal to be evaluated.Cold forming increases both the transition temperature and the strength of the DEs. Nevertheless, toughness against brittle fracture in the CF state is good for all parts of the DEs and girth weld with T27J<−50 °C in the absence of blank welds and <−20 °C when blank welds are present. For PFHT DEs T27J<−50 °C even for the blank welds. T27J was found to correlate with the fracture toughness reference temperature T0 which can be used to determine the minimum operating temperature. The impact toughness of the CF DE can be determined by compressing plate specimens 15% and ageing 30 min at 250 °C. Such a procedure can form the basis for an additional requirement on PxxxM/ML grades when high cold forming strains are involved in vessel manufacture. Ductile fracture is not of concern, as upper shelf toughness remains high in all parts of the DE.The yield and tensile strengths of a CF DE are much greater than those of the cylinder, whereas the membrane stresses on the cylinder are greater than those on the DE. Consequently, design can be safely based on the properties of the nominally unformed cylinder. Furthermore, tensile instability will be first reached in the cylinder before it is reached in the DE, even though Y/T is at its lowest in the cylinder. Secondary bending stresses are greatest at the DE knuckle, but the CF DE has more than sufficient ductility in bending to accommodate the bending strain. The high Y/T of CF DE is combined with high material ductility and is therefore fully acceptable.

AB - The paper describes the results of work done in the Finnish part of the ECOPRESS project on the mechanical properties of pressure vessels made from the TMCP steel grade P420ML2. Dished end (DE)-cylinder assemblies with diameters of 2500 mm and thicknesses of 15 and 30 mm have been examined using DE in both the cold-formed (CF) and CF and post-forming heat treated conditions. The blanks for the DEs contained welds to enable the effect of cold forming on weld metal to be evaluated.Cold forming increases both the transition temperature and the strength of the DEs. Nevertheless, toughness against brittle fracture in the CF state is good for all parts of the DEs and girth weld with T27J<−50 °C in the absence of blank welds and <−20 °C when blank welds are present. For PFHT DEs T27J<−50 °C even for the blank welds. T27J was found to correlate with the fracture toughness reference temperature T0 which can be used to determine the minimum operating temperature. The impact toughness of the CF DE can be determined by compressing plate specimens 15% and ageing 30 min at 250 °C. Such a procedure can form the basis for an additional requirement on PxxxM/ML grades when high cold forming strains are involved in vessel manufacture. Ductile fracture is not of concern, as upper shelf toughness remains high in all parts of the DE.The yield and tensile strengths of a CF DE are much greater than those of the cylinder, whereas the membrane stresses on the cylinder are greater than those on the DE. Consequently, design can be safely based on the properties of the nominally unformed cylinder. Furthermore, tensile instability will be first reached in the cylinder before it is reached in the DE, even though Y/T is at its lowest in the cylinder. Secondary bending stresses are greatest at the DE knuckle, but the CF DE has more than sufficient ductility in bending to accommodate the bending strain. The high Y/T of CF DE is combined with high material ductility and is therefore fully acceptable.

KW - dished ends

KW - cold forming

KW - heat treatment

KW - ProperTune

U2 - 10.1016/j.ijpvp.2004.07.006

DO - 10.1016/j.ijpvp.2004.07.006

M3 - Article

VL - 81

SP - 867

EP - 877

JO - International Journal of Pressure Vessels and Piping

JF - International Journal of Pressure Vessels and Piping

SN - 0308-0161

IS - 10-11

ER -