Strain aging kinetics of vanadium or titanium strengthened high-strength low-alloy steels

It is shown that the minimum in impact toughness of martensitic 12%Cr steels, classically associated with the maximum hardening between 475 and 500 °C, is shifted towards 550 °C in a commercial heat containing phosphorus, while the brittle mode of failure becomes predominantly intergranular. This phenomenon is shown to be typical temper embrittlement induced by the segregation of phosphorus and chromium to the former austenitic grain boundaries, the fragility being amplified by the steel’s relatively high strength. The kinetics of phosphorus segregation are studied by Auger electron spectroscopy. The temperature dependence of equilibrium segregation is shown to be consistent with the theory of synergistic ternary segregation, which is discussed with particular emphasis on the effect of high alloying element concentrations. In particular the high Cr content is responsible for the segregation (thus the embrittlement) to remain significant at much higher temperatures (e.g. 700 °C) than in low alloy steels. Therefore, embrittlement cannot be thoroughly alleviated by a reversion treatment without crossing Ac 1 , unless the phosphorus concentration is kept to a minimum, or molybdenum additions are made which counteract the effect of phosphorus.

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Coarsening kinetics of multicomponent MC-type carbides in high-strength low-alloy steels

Metallurgical and Materials Transactions A ◽

10.1007/s11661-003-0303-x ◽

2003 ◽

Vol 34 (8) ◽

pp. 1565-1573 ◽

Cited By ~ 46

Author(s):

Kaori Miyata ◽

Takahiro Kushida ◽

Tomohiro Omura ◽

Yuichi Komizo

Keyword(s):

High Strength ◽

Low Alloy Steels ◽

Alloy Steels ◽

Coarsening Kinetics ◽

Kinetics Of

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Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074896 ◽

1983 ◽

Vol 41 ◽

pp. 220-221

Author(s):

L.J. Chen ◽

H.C. Cheng ◽

J.R. Gong ◽

J.G. Yang

Keyword(s):

Mechanical Properties ◽

Cooling Rate ◽

Automobile Industry ◽

High Strength ◽

Weight Percent ◽

Low Alloy Steels ◽

Dual Phase ◽

Resource Requirement ◽

Alloy Steels ◽

Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

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