Effect of Zr, Al Addition on Characteristics of MnS and Formation of Intragranular Ferrite in Non-Quenched and Tempered Steel

Lu, Junqiang; Cheng, Guoguang; Tan, Baolin; Che, Julong

doi:10.2355/isijinternational.isijint-2017-617

Cited by 22 publications

(13 citation statements)

References 20 publications

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“…Medium content of sulfur is usually added into steels for their beneficial effects on improving machinability, 9,10) retarding grain growth 11,12) and inducing intragranular ferrite. 11,13,14) However, the large-sized elongated MnS inclusions, which exist in longitudinal section after deformation, are severely detrimental to the transverse mechanical properties of steels. 15,16) Therefore, numerous studies focusing on the control of the morphology, size and distribution of MnS inclusions have been conducted over the years.…”

Section: Introductionmentioning

confidence: 99%

Distribution and Morphology of MnS Inclusions in Resulfurized Non-Quenched and Tempered Steel with Zr Addition

Cheng

Chen³

et al. 2018

ISIJ International

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Distribution and morphology of MnS inclusions in as-cast ingots and as-forged bars of two Zr-bearing resulfurized non-quenched and tempered (NQT) steels have been performed. In the low Zr-bearing steel (0.001 wt%), MnS inclusions, which are teardrop-shaped or rod-like in two-dimensional (2D) morphology and dendritic or skeletal in three-dimensional (3D) morphology, are mainly distributed and segregated at the grain boundaries. While in the high Zr-bearing steel (0.0066 wt%), MnS inclusions are spherical or angular in both 2D and 3D observation and the distribution is more uniform than those in low zirconium steel. The calculated results by Thermo-Calc software show that the content of oxygen is not the direct factor that influences the morphology and distribution of MnS inclusions in medium-sulfur low-oxygen NQT steels. ZrO 2 particles are ideal partcles for generation of spherical type I MnS inclusions owing to their strong nucleation capability and large amounts. However, the Zr and Al contents should be controlled cautiously to avoid generating large-sized agminated complex oxides, which are not easy to float and be removed owing to their high density. Otherwise, the ideal particles ZrO 2 would decrease sharply in number and fail in offering sufficient heterogeneous nuclei for type I MnS inclusions. Besides, high proportion of complex MnS inclusions would decrease the supersaturation when pure MnS inclusions begin to precipitate, suppressing the generation of dendritic type II MnS inclusions.

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Section: Introductionmentioning

confidence: 99%

Distribution and Morphology of MnS Inclusions in Resulfurized Non-Quenched and Tempered Steel with Zr Addition

Cheng

Chen³

et al. 2018

ISIJ International

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“…With the development of the electronic scanning technology, automatic inclusions analysis systems, such as Aspex 20,21) and INCA Explorer, 8,17) are widely applied in steel material research. It can not only obtain abundant size and number characteristics of inclusions within a short time, but the relative position information is also recorded simultaneously, which means this position information can be analyzed to quantify the inclusions distribution characteristics.…”

Section: Effect Of Mns Inclusions Distribution On Intragranular Ferrimentioning

confidence: 99%

“…9) However, the first two factors stated above are almost the same in present study. Hence, inclusions in the steel formed by Zr, O, S and Mn elements, 17) which have been proved to be quite effective as heterogeneous nuclei to promote proeutectoid ferrite, 7,8,[11][12][13] are regarded as the main causes of different microstructures in two sample steels.…”

Section: Microstructuresmentioning

confidence: 99%

“…It should be mentioned that some V(C, N) particles, which are too small to be detected with SEM, have been verified at the edge of MnS inclusions in our previous research. 8 MnS inclusions promoting only one IPF structure. In other words, these agminated MnS inclusions have only provided one nucleation site and most inclusions are wasteful in fact.…”

Section: Ipf Characterizationsmentioning

confidence: 99%

“…4,5) In recent years, intragranular polygonal ferrite (IPF) induced by non-metallic inclusions has been applied to refine the microstructures of ferrite-pearlite steels. [6][7][8][9][10][11][12][13][14] In NQT steel, the primary nucleating agents are MnS + V(C, N) particles, which possess Baker-Nutting orientation relationship with α-Fe and need low energy to form the…”

Section: Introductionmentioning

confidence: 99%

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Effect of MnS Inclusions Distribution on Intragranular Ferrite Formation in Medium Carbon Non-Quenched and Tempered Steel for Large-Sized Crankshaft

Wang

et al. 2019

ISIJ International

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A novel quantitative characterization method of MnS distribution was proposed based on the data from automatic inclusions analysis software to evaluate their effects on intragranular polygonal ferrite (IPF) formation in medium carbon non-quenched and tempered steels. The results show that agminated MnS inclusions in the steel are less effective to promote the IPF formation and lots of inclusions are actually wasteful because their space distances are too small to act as nucleation sites individually, even their number is larger than that in the steel with plentiful uniformly distributed MnS inclusions. Due to the difference of observation method, three-dimensional dendritic MnS inclusions would be revealed as several agminated small-sized ones in two-dimensional observation. In order to avoid misunderstanding, the characteristics of the nearest space distances between inclusions in widely used two-dimensional observation could be applied to recognize and define these agminated MnS inclusions to more accurately evaluate their effects on IPF formation.

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Effects of Zirconium on the Structure and Mechanical Properties of High‐Strength Low‐Alloy Steels under Quenched or Tempered Conditions

Wang

Zheng

Long

et al. 2022

steel research int.

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The effects of zirconium (Zr) on the microstructure, inclusions, Vickers hardness, impact toughness, and tensile properties of quenched and tempered high‐strength low‐alloy (HSLA) steels are investigated. The results show that the addition of Zr is beneficial to the refinement of the grain size of HSLA steels under the two heat treatment conditions. When the Zr content is 0.2 wt%, the average grain size of the steel is the smallest. The main inclusions in Zr‐containing HSLA steels are Zr–O and Zr–O–Mn–S, and the distribution of inclusions in HSLA steels is the most uniform when the Zr content is 0.04 wt%. The addition of an appropriate amount of Zr improves the Vickers hardness of HSLA steels under two heat treatment conditions. In terms of impact toughness, the increase of Zr content is beneficial to improving the room‐temperature impact energy of HSLA steels under two heat treatment conditions, but the improvement of the impact properties of tempered HSLA steels is limited. For tensile properties, the addition of 0.04 wt% Zr is beneficial to increasing the strength of quenched or tempered HSLA steels.

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Effect of Zr, Al Addition on Characteristics of MnS and Formation of Intragranular Ferrite in Non-Quenched and Tempered Steel

Cited by 22 publications

References 20 publications

Distribution and Morphology of MnS Inclusions in Resulfurized Non-Quenched and Tempered Steel with Zr Addition

Distribution and Morphology of MnS Inclusions in Resulfurized Non-Quenched and Tempered Steel with Zr Addition

Effect of MnS Inclusions Distribution on Intragranular Ferrite Formation in Medium Carbon Non-Quenched and Tempered Steel for Large-Sized Crankshaft

Effects of Zirconium on the Structure and Mechanical Properties of High‐Strength Low‐Alloy Steels under Quenched or Tempered Conditions

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