Microalloying concepts and application in long products

Matlock, D. K.; Speer, John G.

doi:10.1179/174328408x322222

Cited by 53 publications

(36 citation statements)

References 14 publications

(29 reference statements)

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“…Interest has increased in the use of microalloyed forging steels in place of quenched-and-tempered steels to realise cost savings [1]. Microalloyed forging steels have been developed over the past several years and are increasingly applied in a variety of large-scale structures, engine, transmission, suspension and driveline components such as the flange, gears, springs, crankshafts, connecting rods, axles and shaft [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effects of tungsten addition and heat treatment conditions on microstructure and mechanical properties of microalloyed forging steels

Zhao

Jiang

Lee

2013

Materials Science and Engineering: A

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In the present work, the effects of tungsten (W) addition and heat treatment conditions on the microstructure, impact toughness and tensile properties of microalloyed forging steels were studied. Four kinds of microalloyed forging steels were produced by varying W additions (0, 0.5, 1 and 2 wt%). Heat treatment was carried out at temperatures ranging from 840 to 950 °C followed by air and furnace cooling. Mechanical tests were used to evaluate the room temperature Charpy impact and tensile properties. The resulting microstructures were analysed via optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the microstructure and mechanical properties of the microalloyed forging steels are closely related to the W content. Correct selection of heat treatment temperature and cooling method is very important to enhance the mechanical properties. The optimum heat treatment temperatures obtained in this study are 920, 900, 880 and 860 °C for the steels with 0%, 0.5%, 1% and 2% W, respectively. Both the impact toughness and tensile properties of the microalloyed forging steels have been significantly enhanced after heat treatment at the optimum temperatures followed by air cooling. AbstractIn the present work, the effects of tungsten (W) addition and heat treatment conditions on the microstructure, impact toughness and tensile properties of microalloyed forging steels were studied. Four kinds of microalloyed forging steels were produced by varying W additions (0, 0.5, 1 and 2 wt.%). Annealing treatment was carried out at temperatures ranging from 840 to 950℃ followed by air and furnace cooling. Mechanical tests were used to evaluate the room temperature Charpy impact and tensile properties. The resulting microstructures were analysed via optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results show that the addition of W plays an important role in increasing the strength and decreasing the toughness of the studied steels. Correct selection of annealing temperature and cooling method is very important to enhance the mechanical properties. The optimum annealing temperatures obtained in this study are 920, 900, 880 and 860℃ for the steels with 0, 0.5, 1 and 2% W, respectively. Both the impact toughness and tensile properties of the microalloyed forging steels have been significantly enhanced after heat treatment at the optimum temperatures followed by air cooling.

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Section: Introductionmentioning

confidence: 99%

Effects of tungsten addition and heat treatment conditions on microstructure and mechanical properties of microalloyed forging steels

Zhao

Jiang

Lee

2013

Materials Science and Engineering: A

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“…mechanical properties or section size and shape of each application [7]. Figure 2-26 shows the substantial differences in microstructures, processing temperature and carbon content of long product application.…”

Section: Microalloying Application On Long Productsmentioning

confidence: 99%

“…However, considering the successful application of microalloying in flat rolling products, this lack of application in long products offers significant opportunities to design new steel to meet more rigorous requirements, e.g. anti-seismic grade rebars or heavy haul rail steels [6,7].…”

Section: Microalloying Application On Long Productsmentioning

confidence: 99%

“…Meanwhile, within the limited research studies [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], it has been reported that Nb additions provide benefits in reducing cost, due to the elimination of any following heat treatment, and improvement in mechanical properties of medium and high carbon steels. Using 0.02 wt% Nb, a successful product Niobras-200 rail steel was developed which provides great performance in heavy haul iron ore service [4].…”

Section: Microalloyed Steelsmentioning

confidence: 99%

“…Figure 2-26 Processing window for different long products application which have the potential to benefit from microalloying addition [7].…”

Section: Microalloying Application On Long Productsmentioning

confidence: 99%

See 2 more Smart Citations

Thermomechanical Processing of Structural Steels with Dilute Niobium Additions

Cui

Patel²,

Palmiere

2016

HSLA Steels 2015, Microalloying 2015 &Amp; Offshore Engineering Steels 2015

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-i - AbstractIn this thesis, the influence of various dilute Nb additions (0.005-0.02 wt%) on austenite microstructure evolution along thermomechanical processing, in terms of austenite recrystallisation and grain growth, were investigated using steels with three carbon content levels.At the homogenisation temperature of 1250°C, all dilute Nb additions were dissolved in low carbon steels whereas the Nb dissolution limits for 0.4 wt% and 0.6 wt% C steels were 0.012 wt% and 0.08 wt%, respectively. Dilute Nb additions did not show significant influence on homogenised austenite grain size. The dramatic increase in C contents was more influential, which decreased the homogenised austenite grain size.The influence of dilute Nb additions and C contents on dynamic recrystallisation behaviour was studied by rough rolling at high deformation temperature with low strain rate. The dilute Nb additions were found to increase the critical strain of dynamic recrystallisation whereas C contents showed no influence on the dynamic recrystallisation behaviour.The austenite recrystallisation behaviour after finish rolling and after the holding period between finishing passes were studied by means of interrupted plane strain compression (PSC) tests and double hit PSC tests. It was found that with low Nb supersaturation, recrystallisation happened prior to Nb precipitation. Solute Nb in austenite delayed the onset of austenite recrystallisation through solute drag effect.With high Nb supersaturation, Nb precipitation occurred before the onset of recrystallisation which completely retarded austenite recrystallisation.The austenite grain growth during the holding period between finish rolling passes was studied by the evolution of prior-austenite grain size before and after the 20s holding period at the highest finish rolling temperature (1050°C). There was no Nb precipitation found and the difference in austenite grain growth behaviour was Abstract -iiattributed to the solute drag effect from both Nb and C in solution. It was found that Nb in solution suppressed austenite grain growth. However, the effectiveness of solute Nb in suppressing austenite grain growth was affected by the C content. Acknowledgement

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