Assessment of Steel Subjected to the Thermomechanical Control Process with Respect to Weldability

Górka, Jacek

doi:10.3390/met8030169

Cited by 35 publications

(37 citation statements)

References 36 publications

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“…The thermomechanically controlled welding process for HSS S700MC requires the consideration of several factors, such as mechanical properties, chemical composition, welding process, and choice of filler wire [10][11][12][13][14][15]. Guo et al [16] used autogenous laser welding (ALW) and multi-pass ultra-narrow gap laser welding (NGLW) in the evaluation of the mechanical properties and microstructure of a welded joint of S700MC and S960QC HSS.…”

Section: Introductionmentioning

confidence: 99%

Effect of Heat Input and Undermatched Filler Wire on the Microstructure and Mechanical Properties of Dissimilar S700MC/S960QC High-Strength Steels

Bayock

Kah

Mvola

et al. 2019

Metals

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The effect of heat input on the microstructure and mechanical properties of dissimilar S700MC/S960QC high-strength steels (HSS) using undermatched filler material was evaluated. Experiments were performed using the gas metal arc welding process to weld three samples, which had three different heat input values (i.e., 15 kJ/cm, 7 kJ/cm, and 10 kJ/cm). The cooling continuous temperature (CCT) diagrams, macro-hardness values, microstructure formations, alloy element compositions, and tensile test analyses were performed with the aim of providing valuable information for improving the strength of the heat-affected zone (HAZ) of both materials. Micro-hardness measurement was conducted using the Vickers hardness test and microstructural evaluation by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The mechanical properties were characterized by tensile testing. Dissimilar welded samples (S700MC/S960QC) with a cooling rate of 10 • C/s (15 kJ/cm) showed a lower than average hardness (210 HV5) in the HAZ of S700MC than S960QC. This hardness was 18% lower compared to the value of the base material (BM). The best microstructure formation was obtained using a heat input of 10 kJ/cm, which led to the formation of bainite (B, 60% volume fraction), ferrite (F, 25% volume fraction), and retained austenite (RA, 10%) in the final microstructure of S700MC, and B (55%), martensite (M, 45%), and RA (10%), which developed at the end of the transformation of S960QC. The results showed the presence of 1.3 Ni, 0.4 Mo, and 1.6 Mn in the fine-grain heat-affected zone of S700MC. The formation of a higher carbide content at a lower cooling rate reduced both the hardness and strength.

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Section: Introductionmentioning

confidence: 99%

Effect of Heat Input and Undermatched Filler Wire on the Microstructure and Mechanical Properties of Dissimilar S700MC/S960QC High-Strength Steels

Bayock

Kah

Mvola

et al. 2019

Metals

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“…The analysis of reference publications [1,5,7,10,18,22] and individual research [4,9,17,38] revealed that, in cases of S700MC steel, the analysis of the phase transformations of austenite was affected by welding thermal cycles and the value of carbon equivalent cannot constitute the only factors taken into consideration during the assessment of weldability. The tested steel has a low carbon content (0.056% by mass), limited primarily by hardening elements (titanium and niobium), which reduces its role in hardening by supersaturation of ferrite and by limiting its action during γ-α transformation.…”

Section: Discussionmentioning

confidence: 99%

“…Before welding, the edges of the plates were dried by being heated at a temperature of 65 °C . The results of strength tests and changes in structure were referred to the joints made using the MAG method [38]. Additional material used solid wire G Mn4Ni1.5CrMo.…”

Section: Welding Processmentioning

confidence: 99%

“…The horizontal position made it possible to prevent the outflow of a significant volume of the liquid weld metal formed during the process, which could take place during welding in the flat position. Before welding, the edges of the plates were dried by being heated at a temperature of 65 • C. The results of strength tests and changes in structure were referred to the joints made using the MAG method [38]. Additional material used solid wire G Mn4Ni1.5CrMo.…”

Section: Welding Processmentioning

confidence: 99%

“…This is due to the reduced concentration of micro-additives as a result of mixing the base material with the filler material. [38].…”

Section: Analysis Of the Welded Jointsmentioning

confidence: 99%

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Assessment of the Effect of Laser Welding on the Properties and Structure of TMCP Steel Butt Joints

Górka

2020

Materials

Self Cite

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The research work and related tests aimed to identify the effect of filler metal-free laser beam welding on the structure and properties of butt joints made of steel 700MC subjected to the TMCP (thermo-mechanically controlled processed) process. The tests involved 10-mm thick welded joints and a welding linear energy of 4 kJ/mm and 5 kJ/mm. The inert gas shielded welding process was performed in the flat position (PA) and horizontal position (PC). Non-destructive testing enabled classification of the tested welded joints as representing the quality level B in accordance with the requirements set out in standard 13919-1. Destructive tests revealed that the tensile strength of the joints was 5% lower than S700MC steel. The results of tensile tests and changes in structure were referred to joints made using the MAG (Metal Active Gas) method. The tests of thin films performed using a high-resolution scanning transmission electron microscope revealed that, during laser beam welding, an increase in dilution was accompanied by an increase in the content of alloying microadditions titanium and niobium, particularly in the fusion area. A significant content of hardening phases in the welded joint during cooling led to significant precipitation hardening by fine-dispersive (Ti,Nb)(C,N) type precipitates being of several nanometres in size, which, in turn, resulted in the reduction of plastic properties. An increase in the concentration of elements responsible for steel hardening, i.e., Ti and Nb, also contributed to reducing the weld toughness below the acceptable value, which amounts to 25 J/cm2. In cases of S700MC, the analysis of the phase transformation of austenite exposed to welding thermal cycles and the value of carbon equivalent cannot be the only factors taken into consideration when assessing weldability.

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Effect of Pulse Current GMAW on the Yield Stress of the S460M TMCP Steel Welded Joints

et al. 2022

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Thermomechanically cold processed (TMCP) steels with a high level of strength are actively used in various constructions. The high strength of the TMCP steels is acquired due to the formation of the fine-grained structure. Such steels have relatively low carbon percentage. These greatly simplify the solution of the problem of improving the quality and reliability of metal structures. At the same time this raises new questions in terms of the technology for welding such steels. In the first instance, it is conditioned by the complex behavior of the TMCP structure under the welding thermal cycle effect. The most important property of the welded joint is yield stress (YS) which characterizes the workability of the whole joint. The estimation of the YS while developing the welding technology is a valuable task for design. This current research has made a complex investigation of the modern welding technique's effect on the behavior of the yield stress formation in TMCP steel welded joints. For progressive technology development, pulse arc welding was used.

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Assessment of Steel Subjected to the Thermomechanical Control Process with Respect to Weldability

Cited by 35 publications

References 36 publications

Effect of Heat Input and Undermatched Filler Wire on the Microstructure and Mechanical Properties of Dissimilar S700MC/S960QC High-Strength Steels

Effect of Heat Input and Undermatched Filler Wire on the Microstructure and Mechanical Properties of Dissimilar S700MC/S960QC High-Strength Steels

Assessment of the Effect of Laser Welding on the Properties and Structure of TMCP Steel Butt Joints

Effect of Pulse Current GMAW on the Yield Stress of the S460M TMCP Steel Welded Joints

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