Achievement of High Ductility and Ultra-high Strength of V-Nb Microalloyed Spring Steel by Austempered Multiphase Microstructure

Chen, Kui; Liu, Fubin; Li, Huabing; Kang, Congpeng; Zhang, Wenchao; Wang, Ao

doi:10.1007/s11661-020-05777-2

Cited by 26 publications

(8 citation statements)

References 47 publications

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“…Over the past few decades, several approaches have been employed to enhance the strength, ductility, and toughness of spring steel. These include controlling the design of the alloy composition [3][4][5], implementing effective heat treatment [2,[6][7][8][9][10], and utilizing microalloying techniques [11,12]. Medium-carbon spring steel with quenched and tempered lath martensite structures has been widely used as spring steel due to its exceptional strength, ductility, and lower decarburization sensitivity [2,4,7].…”

Section: Introductionmentioning

confidence: 99%

Influence of Nickel on Microstructure and Mechanical Properties in Medium-Carbon Spring Steel

Yu,

Zhao,

Zhao

2024

Materials

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The effects of adding nickel on the phase transition temperature, microstructure, and mechanical properties of medium-carbon spring steel have been investigated. The results show that adding nickel reduces the martensite start (Ms) temperature, improves hardenability, and refines the sub-microstructure of the martensite, thereby improving yield stress. The yield strength of martensitic steel increases by approximately 100 MPa due to a synergistic combination of grain refinement strengthening and dislocation strengthening, with an increase in the nickel content from 0 wt.% to 1 wt.%. The cryogenic impact toughness of martensitic steel also improved with a higher nickel content due to packet and block refinement and an increase in the proportion of high-angle grain boundaries (HAGBs).

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Section: Introductionmentioning

confidence: 99%

Influence of Nickel on Microstructure and Mechanical Properties in Medium-Carbon Spring Steel

Yu,

Zhao,

Zhao

2024

Materials

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“…Through microalloying (vanadium, titanium, niobium), and controlling the rolling and cooling process, it is widely used in automobile connecting rods, crankshaft and other parts. [1][2][3][4][5] Adding an appropriate amount of vanadium, titanium and niobium can form fine carbonitride fixed on the austenite grain boundary, preventing austenite grain growth, so vanadium, titanium and niobium elements play the role of refining grain and precipitates strengthening. [6][7][8] However, largesized and angular carbonitride, not only plays an adverse role in grain refinement but also destroys the continuity of the steel matrix, easily becoming a crack source under the action of external forces, seriously deteriorating the performance of steel.…”

Section: Introductionmentioning

confidence: 99%

Precipitate behaviour of large-sized Nb(C, N) in micro-alloyed steel

Li,

Liu,

Zhang

et al. 2024

Ironmaking & Steelmaking: Processes, Products and Applicati

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The large-sized Nb-rich particles become a crack source easily because it is very brittle and will resist deformation under stress. HT-CLSM experiments and thermodynamic calculations were performed to investigate the precipitate behaviour of large-sized Nb(C, N) in micro-alloyed steel. The precipitate composition in the casting specimen was detected to be MnS and Nb-rich particles distributed along the crack. The results suggest the large-sized Nb-rich particles precipitate at the solidification process, instead of liquid. The precipitates for the HT-CLSM specimen is Nb(C, N), and Nb(C, N) is mainly distributed in a chain-like, clustered way in which the growth of Nb(C, N) is limited by the last to solidify region. The size of most Nb(C, N) is between 10 and 30 μm in the length direction, and the size of Nb(C, N) in the width direction tends to decrease with the increase of cooling rate attributed to larger super-cooling degree and weaker diffusion ability of solute atom. Because of solute segregation, a hypo-eutectic reaction occurs, L→Nb(C, N)+ γ-Fe. Nb(C, N) and γ-Fe are interactively precipitated to form a clustered Nb(C, N). When the holding temperature is high, and the cooling rate is rapid, a little liquid exists in the dendrite that is close to the eutectic composition. Because γ-Fe preferentially attaches to the previous dendrite, a divorce eutectic reaction occurs, forming a single Nb(C, N). MnS can act as the nucleation site of Nb(C, N) with the orientation relationship of MnS(100)//NbC(100).

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“…With the growing development of the automobile industry, high strength and high ductility and fatigue resistance of the spring steel are urgently needed. Effective heat treatment and the corresponding microstructure greatly influence the comprehensive properties [3].…”

Section: Introductionmentioning

confidence: 99%

Experimental validation and thermodynamics analysis of (Nb, V)(C, N) coupling precipitation in high-strength spring steel FAS3550

Wang

Zheng

Shi

et al. 2023

Mater. Res. Express

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Based on the thermodynamic coupling model of multiple microelements in steels, the solid solution and coupling precipitation behavior of Nb-V-N-C system quaternary secondary phase was further verified in microalloyed steels, and combining with the engineering practice in high-strength spring steel FAS3550 containing nanoparticles. According to the thermodynamic calculations, the dissolved V (or Nb) content increased with the increasing addition V (or Nb), while decreased with the increase of addition C, N or Nb (or V). The complete dissolution temperature was 1314 °C, and the effective precipitation temperature of carbonitride was 1060 °C in 0.49%C-0.0060%N-0.03%Nb-0.12%V system spring steel FAS3550, the grains in steel began to coarsen above 1100 °C during heat treatment, and the (Nb, V)(C, N) nanoprecipitates were smaller than 100 nm. The strength and plasticity have been improved simultaneously, and its fatigue life has been increased by 13% after optimizing the heat treatment process.

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Achievement of High Ductility and Ultra-high Strength of V-Nb Microalloyed Spring Steel by Austempered Multiphase Microstructure

Cited by 26 publications

References 47 publications

Influence of Nickel on Microstructure and Mechanical Properties in Medium-Carbon Spring Steel

Influence of Nickel on Microstructure and Mechanical Properties in Medium-Carbon Spring Steel

Precipitate behaviour of large-sized Nb(C, N) in micro-alloyed steel

Experimental validation and thermodynamics analysis of (Nb, V)(C, N) coupling precipitation in high-strength spring steel FAS3550

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