scholarly journals Fracture mechanic and charpy impact properties of a crack in weld metal, HAZ and base metal of welded armor steel

2018 ◽  
Vol 13 ◽  
pp. 2059-2064 ◽  
Author(s):  
Aleksandar Cabrilo ◽  
Katarina Geric
Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3571 ◽  
Author(s):  
Zhenyu Fei ◽  
Zengxi Pan ◽  
Dominic Cuiuri ◽  
Huijun Li ◽  
Azdiar A. Gazder

The ballistic performance of armour steel welds using austenitic filler materials is poor on account of the disparity in the mechanical properties of the weld and base metals. Consequently, a novel Keyhole Gas Tungsten Arc Welding process with a trapezoidal AISI309 austenitic stainless steel interlayer was developed to tailor chemical composition and microstructure by controlling the solidification sequence. Results show that the dilution rate in the weld metal region can reach up to 43.5% by placing a specially designed interlayer in between the base metal, providing a major scope for microstructure modification. Detailed weld analysis was undertaken by X-ray diffraction, optical and secondary and transmission electron microscopy, energy dispersive spectroscopy and electron back-scattering diffraction. The results from Vickers hardness indents and Charpy impact toughness testing at −40 °C show that the properties of the weld metal region are comparable to that of the base metal. This is ascribed to the weld metal comprising a two phase microstructure of martensite and retained austenite, which contribute to improvements in strength and toughness, respectively. Furthermore, the tailored chemical composition, microstructure and low temperature phase transformation in the weld metal may reduce the tendency toward both solidification cracking and hydrogen assisted cold cracking.


Author(s):  
J. A. Gianetto ◽  
D. K. Mak ◽  
R. Bouchard ◽  
S. Xu ◽  
W. R. Tyson

The aim of the present work is to quantify the seam weld properties, including both weld metal and heat affected zone regions, for a series of double-submerged-arc welded pipe, and the base metal and bondline regions for an electrical resistance welded linepipe steel. The chemical composition, microstructure, microhardness, tensile properties, Charpy impact toughness and J-integral/crack-tip opening displacement fracture resistance were characterized for linepipe produced between 1953 and 1981. The toughness results of the base metal, heat affected zone and weld metal regions of the older (higher carbon) linepipes were significantly poorer than those obtained for a more modern low-C microalloyed linepipe steel. In the latter case the base metal, HAZ and weld metal regions failed by ductile fracture at room temperature in both fracture toughness (quasi-static) and Charpy impact tests. It was possible to show that there is a linear correlation between the J-integral at 0.2 mm crack growth and the upper shelf Charpy energy. It is, however, important to note that the Charpy transition temperatures of the older pipes are considerably higher than for the modern pipe. In the case of the electrical resistance weld, very poor toughness was observed for the bondline. Fracture occurred along the bondline in a brittle mode (cleavage) that was attributed to the formation of a coarse, relatively hard microstructure and the presence of inclusions along the bondline region. In addition, it was shown using base-metal BxB and Bx2B samples that initiation toughness is a function of the remaining uncracked ligament. This emphasizes the necessity of ensuring that the crack-tip constraint in the test specimens is similar to the constraint in the crack geometry being assessed.


Author(s):  
Mikihiro Sakata ◽  
Tomoaki Kiso ◽  
Masayuki Tanaka ◽  
Yasuhiro Sato

Duplex and super duplex stainless steels are susceptible to thermal aging embrittlement, referred to as 475°C (885°F) embrittlement. The object of this study is to understand the difference in susceptibility to 475°C (885°F) embrittlement of the base metal and the weld metal of these steels. Isothermal aging heat treatment at 300–450 °C (570–840°F) up to 1,000 hours was performed on 22% Cr duplex stainless steel: UNS S32205 and 25% Cr super duplex stainless steel: UNS S32750 and S32760 and these weld metals made using their matching SMAW electrodes or GTAW rods. After heat treatment, the embrittlement behavior was evaluated by Charpy impact test and Vickers hardness test. The results revealed the time-temperature embrittlement curves of the weld metals were displaced to a significantly shorter period of time and extended to lower temperatures compared to those of the corresponding base metals. More importantly, these results suggested that the maximum design temperature limit on these steels currently specified in the ASME Pressure Piping Codes and Boiler and Pressure Vessel Code is not always sufficient to avoid the risk of 475°C (885°F) embrittlement in their welded components.


2017 ◽  
Vol 54 (4) ◽  
pp. 694-699
Author(s):  
Aleksandar Cabrilo ◽  
Miroslav Cvetinov

The process of welding armor steel is a complex process because of possible welding faults, appearing in the weld metal zone in the form of cracks and pores. Austenitic filler material is traditionally used for welding armor steels. For heavy structural engineering such as armored military vehicles, which are frequently under the effect of dynamic load, it is important to know the dynamic properties of the most sensitive area of welded joints, the weld metal zone. Due to a significant interest in quantification of material resistance to crack initiation and propagation, the fatigue crack growth rate was measured in the welded metal zone, while the resistance to crack growth in the weld metal was tested by the amount of austenite transformed into martensite. Accordingly, the threshold stress concentration factor was 10 MPa m1/2. XRD spectral analysis revealed direct transformation of g - austenite into a� -martensite.


Alloy Digest ◽  
2002 ◽  
Vol 51 (5) ◽  

Abstract Nimrod 617KS is an Inconel-type consumable with a nominal composition of nickel, 24% Cr,12% Co, and 9% Mo and is used to join UNS N06617 and Nicrofer 6023 to themselves. The alloy is designed for high-temperature service and is often used as the weld metal in dissimilar cases to ensure the weld is as strong as the base metal. This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness. It also includes information on heat treating and joining. Filing Code: Ni-583. Producer or source: Metrode Products Ltd.


Author(s):  
Emre Korkmaz ◽  
Cemal Meran

In this study, the effect of gas metal arc welding on the mechanical and microstructure properties of hot-rolled XPF800 steel newly produced by TATA Steel has been investigated. This steel finds its role in the automotive industry as chassis and seating applications. The microstructure transformation during gas metal arc welding has been analyzed using scanning electron microscope, optical microscope, and energy dispersive X-ray spectrometry. Tensile, Charpy impact, and microhardness tests have been implemented to determine the mechanical properties of welded samples. Acceptable welded joints have been obtained using heat input in the range of 0.28–0.46 kJ/mm. It has been found that the base metal hardness of the welded sample is 320 HV0.1. On account of the heat-affected zone softening, the intercritical heat-affected zone hardness values have diminished ∼20% compared to base metal.


Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2357 ◽  
Author(s):  
Li Cui ◽  
Zhibo Peng ◽  
Xiaokun Yuan ◽  
Dingyong He ◽  
Li Chen

Autogenous laser welding of 5A90 Al–Li alloy sheets in a butt-joint configuration was carried out in this study. The microstructure characteristics of the weld metal and base metal in the horizontal surface and the transverse section of the welded joints were examined quantitatively using electron back scattered diffraction (EBSD) technique. The results show that the weld metal in the horizontal surface and the transverse section exhibits similar grain structural features including the grain orientations, grain shapes, and grain sizes, whereas distinct differences in the texture intensity and misorientation distributions are observed. However, the base metal in the horizontal surface and the transverse section of the joints reveals the obvious different texture characteristics in terms of the grain orientation, grain morphology, predominate texture ingredients, distribution intensities of textures, and grain boundary misorientation distribution, resulting in the diversity of the microhardness in the base metal and the softening of the weld metal. However, the degree of the drop in the hardness of the weld metal is highly correlated to the microtexture developed in the base metal.


2003 ◽  
Vol 44 (1) ◽  
pp. 206-210 ◽  
Author(s):  
H. Tanigawa ◽  
K. Shiba ◽  
M. A. Sokolov ◽  
R. L. Klueh

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