Effect of Process Parameters on Microstructural Evolution and Grain Refinement in a Low Carbon High Strength Microalloyed Dual Phase Steel

The effects of process parameters on microstructural evolution and grain refinement are determined in a Nb-Ti microalloyed high strength dual phase steel. With the increase of cooling rate, final microstructures change from a mixture of acicular ferrite (AF)+martensite/retained austenite (M/A) to conventional bainite (CB)+M/A. Accordingly, the morphology of M/A constituent changes from an equiaxed island in AF to an elongated interlath in CB. The length and width of bainite packets become smaller with the increase of cooling rate and the decrease of deformation temperature. The length of individual bainitic ferrite plates within the packets become smaller with the increase of cooling rate and the decrease of deformation temperature, whereas the thickness of them varies slightly with them. The optimized relaxing time on grain refinement is 60 s. The reheating temperature, reduction ratio and interrupt temperature has no obvious effect on the formation of dual phase of acicular ferrite or bainite and M/A.

Download Full-text

Thermo-Mechanical Simulation of Ultra-High Strength Ferrite-Bainite Dual Phase Steel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.184-185.1367 ◽

2012 ◽

Vol 184-185 ◽

pp. 1367-1370

Author(s):

Wei Lv ◽

Di Wu ◽

Zhuang Li

Keyword(s):

Cooling Rate ◽

Dual Phase Steel ◽

High Strength ◽

Solute Drag ◽

Dual Phase ◽

Drag Effect ◽

Dp Steel ◽

Mechanical Simulation ◽

Austenite Grain ◽

Fast Cooling

In the present paper, thermo-mechanical simulation of ultra-high strength ferrite-bainite dual phase (DP) steel was performed using a thermomechanical simulator. Continuous cooling transformation (CCT) diagram was constructed for DP steel. The effects of composition and cooling rate on the kinetics and products of phase transformation and the form of the CCT diagram were investigated. The results have shown that the α→γ transformation in DP steel was found to be more sluggish due to the addition of alloying elements. The segregation of manganese and niobium at austenite grain boundaries is expected to cause a solute drag effect, thereby reducing the rate of γ→α transformation in DP steel. The pearlite transformation region disappeared for cooling rates from 0.1 to 20°C/s. The microstructure comprises of bainite and martenite was obtained at fast cooling rate. The present steel is expected to have a higher hardenability.

Download Full-text

Experimental and Numerical Investigation on the Effect of the Tempcore Process Parameters on Microstructural Evolution and Mechanical Properties of Dual-Phase Steel Reinforcing Rebars

Metals and Materials International ◽

10.1007/s12540-020-00840-4 ◽

2020 ◽

Cited By ~ 1

Author(s):

Mohammad Reza Akbarpour ◽

Amirhossein Mashhuriazar ◽

Mohammad Daryani

Keyword(s):

Mechanical Properties ◽

Numerical Investigation ◽

Microstructural Evolution ◽

Process Parameters ◽

Dual Phase Steel ◽

Dual Phase ◽

Tempcore Process

Download Full-text

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).

Download Full-text