A Crack Arrest Test Using a Toughness Gradient Steel Plate

1995 ◽  
Vol 117 (4) ◽  
pp. 330-334 ◽  
Author(s):  
H. Okamura ◽  
G. Yagawa ◽  
T. Hidaka ◽  
Y. Urabe ◽  
M. Satoh ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Steel Plate ◽  
Crack Arrest ◽  
Steel Plates ◽  
Brittle Crack ◽  
Four Point Bending ◽  
Heavy Section ◽  
Bending Load ◽  
Plate Specimen ◽  
Arrest Toughness

A crack arrest test was carried out using a toughness gradient steel plate with three layers to study the concept of crack arrest toughness. Four-point bending load with thermal shock was applied to the large flat plate specimen with a surface crack. Five crack initiations and arrests were observed during the test and the propagated crack bifurcated. Finally, cracks were arrested at the boundary of the first and the second layer, except for a small segment of the crack. The first crack initiation took place slightly higher than the lower bound of KIc data obtained by ITCT specimens. That is, the KIC concept for brittle crack initiation was verified for heavy section steel plates. The first crack arrest took place within the scatter band of KIa and KId data for the first layer. That is, the KIa concept appears applicable for crack arrest of a short crack jump.

Brittle Crack Propagation/Arrest Behavior in T-Joint Structure of Heavy Gauge Steel Plates

2012 ◽  
Vol 706-709 ◽  
pp. 914-919 ◽  
Author(s):  
Tsunehisa Handa ◽  
Kimihiro Nishimura ◽  
Hiroshi Shiomi ◽  
Seishi Tsuyama
Keyword(s):  
Crack Propagation ◽  
Steel Plate ◽  
Crack Arrest ◽  
Steel Plates ◽  
Brittle Crack ◽  
K Value ◽  
Joint Structure ◽  
Large Heat ◽  
Large Container ◽  
Arrest Toughness

Brittle crack arrestability is extremely important in welded joints of heavy gauge steel plates used in large container ships. Recently, much attention has been focused on potential crack propagation along welds using large heat input. This paper examines the application of a T-joint to the strength deck structure of container ships to enhance crack arrestability. The crack arrest toughness, Kca, for crack arrest was varied. The ESSO test of T-joint components showed that brittle crack was arrested at the T-joint if the steel plate used for the flange had a high Kca value in the range from 4900 to 7300N/mm3/2. FE-analysis of the stress intensity factor K indicated that brittle crack propagation was arrested under the condition that the K-value at the running crack tip was less than the Kca of the material. In the T-joint, it was noted that the K-value around the area of the deepest point of the crack decreased and was finally less than the Kca of the flange plate when the brittle crack penetrated suddenly into the flange plate to a 10mm depth. This phenomenon shows the advantage of using a T-joint for brittle crack arrest in the flange plates of strength deck structures.

Study on Unstable Brittle Crack Arrest Toughness of Extremely-Low Carbon Bainitic Steel Plates

Materials ◽  
2004 ◽  
Author(s):  
Tsunehisa Handa ◽  
Takahiro Kubo ◽  
Keniti Amano ◽  
Mitsuhiro Okatsu ◽  
Kazunori Miyamoto ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Cross Section ◽  
Test Piece ◽  
Main Crack ◽  
Crack Arrest ◽  
Steel Plates ◽  
Bainitic Steel ◽  
Low Carbon ◽  
Brittle Crack ◽  
Arrest Toughness

The extremely-low carbon bainitic steel (ELCB steel) is a high strength steel with about 0.02 mass% or less carbon. In this research, unstable brittle crack arrest toughness of ELCB steel plates was investigated by temperature-gradient ESSO tests, compared with that of conventional TMCP steel plates. Both of ELCB and TMCP steel plates without pre-straining had sufficient crack-arrest toughness at 0°C. After 10% prestraining, the TMCP steel plate had not sufficient crack-arrest toughness at 0 °C . The ELCB steel plates, however, maintained high crack arrest toughness at 0°C. even after 10% pre-straining. ELCB steel were also different from TMCP steels in the correlation between transition temperature of crack arrest toughness and fracture appearance transition temperature (vTrs) obtained by Charpy impact test. When the vTrs of an ELCB steel and that of a TMCP steel were the same value, crack arrest toughness of an ELCB steel was higher than that of a TMCP steel. In the cross section of the ESSO test piece of the ELCB steels, many sub-cracks and micro-crack branching were observed. However, in the cross section of the ESSO test piece of the conventional TMCP steels, there were few subcracks and branching. Initiation of sub-cracks and branching around the main crack tip reduces the stress intensity factor of the main crack. It was considered that the above features of the ELCB steel were caused by initiation of sub-cracks and branching at the tip of the main brittle crack.

scholarly journals Unstable Brittle Crack-Arrest Toughness of Newly Developed Steel Plate with Surface Layers having Ultra Fine Grain Microstructure (2)

1995 ◽  
Vol 1995 (178) ◽  
pp. 555-563 ◽  
Author(s):  
Tadashi Ishikawa ◽  
Takehiro Inoue ◽  
Yukito Hagiwara ◽  
Shigeru Ohshita ◽  
Takao Kuroiwa ◽  
...  
Keyword(s):  
Steel Plate ◽  
Crack Arrest ◽  
Brittle Crack ◽  
Surface Layers ◽  
Fine Grain ◽  
Arrest Toughness

scholarly journals Simplified Evaluation Method for Brittle Crack Arrest Toughness of Steel Plates Exploiting Charpy Impact Test

2018 ◽  
Vol 104 (3) ◽  
pp. 155-165 ◽  
Author(s):  
Hiroyuki Shirahata ◽  
Teppei Okawa ◽  
Takehiro Inoue ◽  
Kohsaku Ushioda
Keyword(s):  
Evaluation Method ◽  
Impact Test ◽  
Charpy Impact ◽  
Crack Arrest ◽  
Charpy Impact Test ◽  
Steel Plates ◽  
Brittle Crack ◽  
Arrest Toughness

Fracture Toughness of Thick Steel Plates for Shipbuilding

2008 ◽  
Vol 580-582 ◽  
pp. 89-92
Author(s):  
Joon Sik Park ◽  
B.Y. Jung ◽  
Hiroshi Yajima ◽  
Jong Bong Lee
Keyword(s):  
Fracture Toughness ◽  
Crack Initiation ◽  
Large Scale ◽  
Steel Plate ◽  
Plate Thickness ◽  
Steel Plates ◽  
Initiation And Propagation ◽  
Thick Steel ◽  
Test Result ◽  
Grade Steel

In this study, the effect of thickness on the fracture toughness of the steel plate with the thickness of 80mm has been investigated by the wide plate tensile test and ESSO test. The fracture toughness for crack initiation and propagation was evaluated quantitatively for the full thickness specimen. It was found that EH-36 grade steel with the thickness of 80mmt showed the KIC value of 164kgf/mm1.5 at -145°C. Also, large-scale ESSO test result showed that the steel with the thickness of 80mm had 520kgf/mm1.5 at -10°C. Although it was known that the fracture toughness decreases with the increase of the plate thickness, EH-36 grade steel with the thickness of 80mm had enough values of fracture toughness to prevent the crack initiation and arrest the brittle crack propagation.

Simplified Evaluation of Brittle Crack Arrest Toughness in Heavy-thick Plate by Combined Small-scale Tests

2017 ◽  
Vol 27 (2) ◽  
pp. 210-215 ◽  
Author(s):  
Teppei Okawa ◽  
Hiroyuki Shirahata ◽  
Kiyotaka Nakashima ◽  
Kazuhisa Yanagita ◽  
Takehiro Inoue
Keyword(s):  
Thick Plate ◽  
Crack Arrest ◽  
Small Scale ◽  
Brittle Crack ◽  
Arrest Toughness

Crack Arrest Toughness of a Heat-Affected Zone Containing Local Brittle Zones

1996 ◽  
Vol 118 (4) ◽  
pp. 292-299 ◽  
Author(s):  
L. Malik ◽  
L. N. Pussegoda ◽  
B. A. Graville ◽  
W. R. Tyson
Keyword(s):  
Crack Initiation ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Weld Zone ◽  
Crack Arrest ◽  
Attractive Alternative ◽  
Initiation Toughness ◽  
Fusion Boundary ◽  
Arrest Toughness ◽  
Fast Fracture

The awareness of the presence of local brittle zones (LBZs) in the heat-affected zone (HAZ) of welds has led to the requirements for minimum initiation (CTOD) toughness for the HAZ for critical applications (API RP 2Z, CSA S473). Such an approach, however, is expensive to implement and limits the number of potential steel suppliers. A fracture control philosophy that is proposed to be an attractive alternative for heat-affected zones containing LBZs is the prevention of crack propagation rather than of crack initiation. Such an approach would be viable if it could be demonstrated that cracks initiated in the LBZs will be arrested without causing catastrophic failure, notwithstanding the low initiation (CTOD) toughness resulting from the presence of LBZs. Unstable propagation of a crack initiating from an LBZ requires the rupture of tougher microstructural regions surrounding the LBZ in HAZ, and therefore the CTOD value reflecting the presence of LBZ is unlikely to provide a true indication of the potential for fast fracture along the heat-affected zone. Base metal specifications (CSA S473) usually ensure that small unstable cracks propagating from the weld zone into the base metal would be arrested. Past work has also shown that unstable crack initiation resulting from interaction of surface semi-elliptical cracks parallel to the fusion boundary with the local brittle zones can get arrested once the crack has popped through the depth of the LBZ. However, the potential for arrest when a through-thickness HAZ crack runs parallel to the fusion boundary, and thus parallel to the LBZs, has not been examined previously. To investigate the likelihood of fast fracture within the HAZ, a test program has been carried out that involved performing compact plane strain (ASTM E1221) and plane stress crack arrest tests on a heataffected zone that contained LBZs, and thus exhibited unacceptable low CTOD toughness for resistance to brittle fracture initiation. The results indicated that in contrast to the initiation toughness (CTOD toughness), the crack arrest toughness was little influenced by the presence of local brittle zones. Instead, the superior toughness of the larger proportion of finer-grain HAZ surrounding the LBZ present along the crack path has a greater influence on the crack arrest toughness. It further seems that there may be potential to estimate the HAZ crack arrest toughness from more conventional smaller-scale laboratory tests, such as conventional or precracked instrumented Charpy impact tests.

Safety of Mega Container Ship Focusing on Brittle Crack Initiation and Arrest Behavior of Heavy Thickness Plate

2008 ◽  
Author(s):  
Masanobu Toyoda ◽  
Noboru Kiji ◽  
Yoshiyuki Nakajima ◽  
Tetsuo Okada ◽  
Yasumasa Nakanishi ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Crack Initiation ◽  
Yield Strength ◽  
Base Metal ◽  
Steel Plate ◽  
Brittle Crack ◽  
Hull Structure ◽  
Structural Details ◽  
Weld Structure ◽  
Welding Joints

The enlargement of containership requires the higher tensile strength steel and thicker plate around the hatch coaming more than the prescribed classification rules. These call the concerns about the safety of brittle crack initiation and arrestability of hull structure. It is known that increasing of stress and thickness of plates will reduce the toughness of base metal and welding joints. Therefore, the authors conducted to assure the toughness of base metal and welding joint for new higher tensile strength steel of 460MPa yield strength (YP460) and 60mm thickness. It has been considered that weld assembled steel plate structure has some arrestability at intersections of plates, though there are no prescription on the rules. And it was reported that very thicker mother plate has not enough toughness to arrest brittle crack recently. The authors investigated the structural arrestability by model testing and FE analysis and established it. Furthermore, structural details for intersections were also established. Both preventing the brittle crack initiation and arresting the brittle crack of weld structure were described, focusing on developing higher yield strength and heavier thickness of YP460 for containership in this paper.

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