MICROSTRUCTURE EFFECT ON THE RESISTANCE TO THE IMPACT OF FERRITIC STEEL WELD METALS

The impact toughness of low-Cr heat-resistant steel weld metal is an important problem to broaden the application of low-Cr heat-resistant steel. In this study, the microstructure and impact toughness of 12Cr1MoVR low-alloy heat-resistant steel weld metals with various boron contents (B1 = 0.0028%, B2 = 0.0054%, and B3 = 0.0079%) were investigated. The microstructures of all weld metals were composed of block ferrite, carbides, and inclusions. Results indicated that with increased B content, prior austenite grain sizes decreased, and minor microstructure changes could be found. With the increase in B content from 0.0028% to 0.0054% to 0.0079%, the ductile–brittle transition temperature of the weld metals decreased from 30 to 0 to −14 °C, the toughness of weld metal increased, and the hardness slightly decreased, all of which are directly related to the refinement of prior austenite grain size because of the addition of B content. However, on the top-shelf zone, such as at the testing temperature of 80 °C, ductile fracture dominates the fracture surface; with the increase in B content, the size and density of inclusions increased gradually, which led to the decrease of the impact toughness at 80 °C when the B content was 0.0079%.

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EBSD characterisation of grain size distribution and grain sub-structures for ferritic steel weld metals

Welding in the World ◽

10.1007/s40194-021-01225-w ◽

2022 ◽

Author(s):

Pauli Lehto ◽

Heikki Remes

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Cell Size ◽

Ferritic Steel ◽

Weighted Average ◽

Dislocation Cell ◽

Steel Weld ◽

Weld Metals ◽

Average Grain Size ◽

Dislocation Cell Size

AbstractMicrostructural characterisation of engineering materials is required for understanding the relationships between microstructure and mechanical properties. Conventionally grain size is measured from grain boundary maps obtained using optical or electron microscopy. This paper implements EBSD-based linear intercept measurement of spatial grain size variation for ferritic steel weld metals, making analysis flexible and robust. While grain size has been shown to correlate with the strength of the material according to the Hall–Petch relationship, similar grain sizes in weld metals with different phase volume fractions can have significantly different mechanical properties. Furthermore, the solidification of the weld pool induces the formation of grain sub-structures that can alter mechanical properties. The recently developed domain misorientation approach is used in this study to provide a more comprehensive characterisation of the grain sub-structures for ferritic steel weld metals. The studied weld metals consist of varying mixtures of primary ferrite, acicular ferrite, and bainite/martensite, with large differences observed in hardness, grain size, grain morphology, and dislocation cell size. For the studied weld metals, the average dislocation cell size varied between 0.68 and 1.41 µm, with bainitic/martensitic weld metals showing the smallest sub-structures and primary ferrite the largest. In contrast, the volume-weighted average grain size was largest for the bainitic/martensitic weld metal. Results indicate that a Hall–Petch-type relationship exists between hardness and average dislocation cell size and that it partially corrects the significantly different grain size—hardness relationship observed for ferritic and bainitic/martensitic weld metals. The methods and datasets are provided as open access.

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Welding. Determination of Ferrite Number (FN) in austenitic and duplex ferritic-austenitic Cr-Ni stainless steel weld metals

10.3403/02021716 ◽

2000 ◽

Cited By ~ 1

Keyword(s):

Stainless Steel ◽

Steel Weld ◽

Ferrite Number ◽

Weld Metals ◽

Stainless Steel Weld

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Relationship between Microstructure and Corrosion Behavior of Stainless Steel Weld Metals

JOURNAL OF THE JAPAN WELDING SOCIETY ◽

10.2207/jjws.89.538 ◽

2020 ◽

Vol 89 (8) ◽

pp. 538-550

Author(s):

Hiroshige INOUE

Keyword(s):

Stainless Steel ◽

Corrosion Behavior ◽

Steel Weld ◽

Weld Metals ◽

Stainless Steel Weld

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Investigation of fracture and determination of fracture toughness of modified 9Cr–1Mo steel weld metals using AE technique

Materials Science and Engineering A ◽

10.1016/s0921-5093(99)00190-2 ◽

1999 ◽

Vol 270 (2) ◽

pp. 260-266 ◽

Cited By ~ 21

Author(s):

Xin Long ◽

Guangjun Cai ◽

Lars-Erik Svensson

Keyword(s):

Fracture Toughness ◽

Steel Weld ◽

Weld Metals

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Effects of oxygen content on microstructure and impact toughness of high heat input flux-cored wire weld metals

Metallurgical Research & Technology ◽

10.1051/metal/2018012 ◽

2018 ◽

Vol 115 (4) ◽

pp. 410

Author(s):

Fengyu Song ◽

Yanmei Li ◽

Ping Wang ◽

Fuxian Zhu

Keyword(s):

Grain Size ◽

Impact Toughness ◽

Weld Metal ◽

Oxygen Content ◽

Heat Input ◽

High Heat ◽

Cored Wire ◽

Weld Metals ◽

High Heat Input ◽

The Impact

Three weld metals with different oxygen contents were developed. The influence of oxygen contents on the microstructure and impact toughness of weld metal was investigated through high heat input welding tests. The results showed that a large number of fine inclusions were formed and distributed randomly in the weld metal with oxygen content of 500 ppm under the heat input condition of 341 kJ/cm. Substantial cross interlocked acicular ferritic grains were induced to generate in the vicinity of the inclusions, primarily leading to the high impact toughness at low temperature for the weld metal. With the increase of oxygen content, the number of fine inclusions distributed in the weld metal increased and the grain size of intragranular acicular ferrites decreased, which enhanced the impact toughness of the weld metal. Nevertheless, a further increase of oxygen content would contribute to a great diminution of the austenitic grain size. Following that the fraction of grain boundary and the start temperature of transformation increased, which facilitated the abundant formation of pro-eutectoid ferrites and resulted in a deteriorative impact toughness of the weld metal.

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