An assessment of a CrMoV cast steel weld joint for dynamic fracture behaviour
TL;DR: In this article, a composite weld joint with crack front enveloping all the three zones simultaneously is found to be an appropriate configuration for conservative fracture mechanics based design analysis, and the crack tolerance capacities for each of the weld configurations investigated are illustrated.
About: This article is published in Engineering Fracture Mechanics.The article was published on 1988-01-01. It has received 8 citations till now. The article focuses on the topics: Fracture mechanics & Charpy impact test.
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15 Aug 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the authors investigated the dynamic mechanical behavior of a welded joint of high-strength, low alloy (HSLA) 100 steel by both quasistatic and high strain rate (103 s � 1 ) tension loadings at ambient and low temperatures.
Abstract: The dynamic mechanical behavior of a welded joint of high-strength, low alloy (HSLA) 100 steel was investigated by both quasistatic (103 s � 1 ) and high strain rate (103 s � 1 ) tension loadings at ambient and low temperatures. The constitutive responses for the microstructurally different weld and base steels, along with the interface, which included the heat-affected zone (HAZ), were analyzed and compared. This response is successfully modeled by the mechanical threshold stress (MTS) constitutive equation for different regions of the welded joint, which shows qualitatively different behavior. The necking and failure occurred uniformly within the weld metal but not in the HAZ. The main mechanism for the failure of the welded joints is void growth. Microstructural characterization revealed that the nucleation of voids occurred mainly at the interface between the base and the weld metal, and initiated at inclusions. Measurements of damage distributions across HAZ were made to evaluate the contribution of porosity variation to the constitutive response. In both the quasi-static and dynamic tests, the deformation localization in the form of necking first appeared in the weld metal. Fractographic observation demonstrates that void evolution is a dominant factor in the macroscopic mechanical response. The Gurson � /Tvergaard model was included in the modeling effort to incorporate the effect of void opening on the mechanical response as well as tensile instability. The MTS constitutive model was successfully implemented to the tensile regime of loading. # 2003 Elsevier Science B.V. All rights reserved.
43 citations
TL;DR: Instrumented Charpy impact testing has been used for evaluating the dynamic fracture behavior of mis-matched Q&T steel weldments as discussed by the authors, and the effect of strength mis-match on the Dynamic fracture toughness (JId) and dynamic crack resistance curves (Jd-R) of HAZ and weld metals specimens are discussed.
30 citations
TL;DR: In this paper, an attempt was made to study dynamic fracture toughness of the armour grade quenched and tempered steel and their welds fabricated using low hydrogen ferritic steel (LHF) consumables.
Abstract: The armour grade quenched and tempered steel joints fabricated using low hydrogen ferritic steel (LHF) filler exhibited superior joint efficiency owing to preferential ferrite microstructure in the welds and also they offered required resistance to HIC. However, the combat vehicles used in military operations will be required to operate under a wide range of road conditions ranging from first class to cross country. Structural components in combat vehicles are subjected to dynamic loading with high strain rates during operation. Stress loadings within the vehicle hull of these vehicles are expected to fluctuate considerably and structural cracking especially in welds during the service life of these vehicles can lead to catastrophic failures. Under these conditions, fracture behaviour of high strain rate sensitive structural steels can be better understood by dynamic fracture toughness (K1d). Hence, an attempt was made to study dynamic fracture toughness of the armour grade quenched and tempered steel and their welds fabricated using LHF consumables. The experimental results indicate that the K1d values of the joints fabricated by shielded metal arc welding (SMAW) are higher than those of the joints fabricated using flux cored arc welding (FCAW) process.
19 citations
TL;DR: In this paper, a center-cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behavior of welded joints, utilizing a servo-hydraulic-controlled fatigue testing machine at constant amplitude loading (R=0).
Abstract: Welding of high-strength low-alloy (HSLA) steels involves the use of low-strength, equal-strength, and high-strength filler materials (electrodes) compared with the parent material, depending on the application of the welded structures and the availability of filler material. In the present investigation, the fatigue crack growth behavior of weld metal (WM) and the heat-affected zone (HAZ) of undermatched (UM), equally matched (EM), and overmatched (OM) joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) has been used to fabricate the butt joints. A center-cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behavior of welded joints, utilizing a servo-hydraulic-controlled fatigue-testing machine at constant amplitude loading (R=0). The effect of notch location on the fatigue crack growth behavior of strength mismatched HSLA steel weldments also has been analyzed.
16 citations
TL;DR: In this article, the authors examined how shielded metal arc welding consumables affect the dynamic fracture toughness (J1d) of armor-grade quenched and tempered (Q&T) steels.
Abstract: Austenitic stainless steel, low hydrogen ferritic steel and high nickel steel consumables are used for the welding of armor-grade quenched and tempered (Q&T) steels. The use of such consumables in the welding of armorgrade Q&T steel leads to the formation of distinct microstructures in the respective welds and has a major influence on the dynamic fracture toughness. Hence, this paper examines how shielded metal arc welding consumables affect the dynamic fracture toughness (J1d) of armor-grade Q&T steel joints. The J1d values of joints fabricated with high nickel steel joints are superior than all other joints.
12 citations
References
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TL;DR: In this article, the fracture behavior of 52100 steel hardened and tempered to RC62 has been investigated as a function of austenitizing over the temperature range from 800 to 1100°C.
Abstract: The fracture behavior of 52100 steel hardened and tempered to RC62 has been investigated as a function of austenitizing over the temperature range from 800 to 1100°C. Specimens were homogenized at 1150°C and either furnace cooled or isothermally transformed at 580°C to produce a pearlitic microstructure prior to austenitizing for hardening. Furnace-cooled specimens developed a proeutectoid carbide network that did not dissolve during subsequent austenitizing below Acm. The residual proeutectoid carbides and the carbide-free martensite-austenite structure between them controlled fracture and produced KIC of 19 MPa \ m1/2, the highest determined in this investigation. The specimens isothermally transformed prior to austenitizing below Acm produced a microstructure of fine spherical carbides dispersed throughout a fine martensitic matrix and did not contain residual proeutectoid carbides. The transgranular fracture of the latter specimens by microvoid coalescence around the closely spaced spherical carbides resulted in the lowest values of fracture toughness, 14 to 16 MPa\ m1/2, determined in these experiments. Austenitizing above Acm caused solution of all carbides, a gradual coarsening of the austenitic grain size, a transition to plate martensite, and an increase in retained austenite. Fracture toughness increased slightly with increasing austenitizing temperature above Acm despite the fact that fracture propagated primarily along the austenitic grain boundaries. The improved fracture toughness, verified by scanning electron microscopy of the fatigue crack-overload fracture interface, is believed to be caused in part by transgranular crack propagation during the first stages of crack extension that are most important in determining K1C.
25 citations
TL;DR: In this paper, the dynamic fracture toughness, K I d, was measured in a number of ferrous alloys using precracked Charpy specimens and an instrumented impact machine.
Abstract: The dynamic fracture toughness, K I d , was measured in a number of ferrous alloys using precracked Charpy specimens and an instrumented impact machine. The alloys investigated included quenched and tempered steels (H-11, D6AC, and 4340), 18Ni maraging steels (grades 200, 250, and 300) and a high-temperature, stainless maraging steel (Pyromet X-15). Standard Charpy specimens were precracked in fatigue and tested at either 72°F (22°C) or -65°F (-54°C). Values of K I d were determined as a function of yield strength and microstructure, and correlations were established between K I d and both the energy to initiate fracture, W m /A, and the total energy of fracture, W/A. The instrumented, precracked Charpy test is shown to be a convenient method of determining relative fracture toughness; under proper conditions this test procedure can be used to determine the dynamic plane-strain fracture toughness.
14 citations
TL;DR: In this article, the ASME SA533 Gr A Cl 2 narrow gap, gas tungsten arc weldments (minimum yield strength equals 70 ksi, 485 MPa) were evaluated at low temperatures while Jintegral techniques were utilized to evaluate dynamic fracture toughness over the transition and upper shelf temperature ranges.
9 citations
TL;DR: In this article, lower bound dynamic fracture toughness parameters for HY-80 and HY-130 steel and their weld metals are identified, with the emphasis on reasonable lower bound values at 30°F for use in elastodynamic analyses of crack growth initiation, propagation and arrest in ship structures.
4 citations