Coupled Temperature-Microstructure Model for Predicting Temperature Distribution and Phase Transformation in Steel for Arbitrary Cooling Curves

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Sandip K. Saha ◽  
Akhilesh Kumar
Keyword(s):  
Heat Transfer ◽  
Phase Transformation ◽  
Steel Plate ◽  
Plate Thickness ◽  
High Strength Steels ◽  
High Strength ◽  
Rolling Speed ◽  
Transfer Model ◽  
Advanced High Strength Steels ◽  
Quenching Time

Abstract This study aims at developing a numerical model that can be employed for simulating the thermomechanical treatment to develop the advanced high strength steels. The developed numerical method is used to calculate the heat transfer coefficient of the quenching medium during the continuous cooling of the steel using the inverse heat transfer model for predefined cooling paths. Further, the phase transformation models are used to predict the final microstructure of the steel plate. The cooling rate, plate thickness, and rolling speed are varied to evaluate the temperature and microstructure distribution in the steel plate. It is found that on increasing the quenching time, the transformation fraction from austenite to ferrite and bainite phases increases and the corresponding martensite fraction decreases. The temperature variation in the plate is significant due to the change in plate thickness and rolling speed for a given quenching time. The present model will be useful for designing process parameters to obtain desired microstructures in third-generation advanced high strength steels.

DESIGN PARAMETERS SELECTION OF SPRINGBACK EFFECT IN AIR-V BENDING USING TAGUCHI APPROACH ON ADVANCE HIGH STRENGTH STEEL-DP590

2015 ◽  
Vol 76 (3) ◽  
Author(s):  
Shahrul Azam Abdullah ◽  
Muhamad Sani Buang ◽  
Juri Saedon ◽  
Hashim Abdullah
Keyword(s):  
Plate Thickness ◽  
High Strength Steels ◽  
High Strength ◽  
Design Parameters ◽  
Optimum Level ◽  
Advanced High Strength Steels ◽  
Parameters Selection ◽  
Bending Process ◽  
Punch Radius ◽  
Evaluation Problem

Advanced High Strength Steels (AHSS) are increasingly utilized especially in automotive industry. However, forming of AHSS is challenging particularly in prediction of springback effect caused by material properties, tools and dies parameters, work material and bending technique factors. An air V-bending process was chosen as an evaluation problem because it showed larger springback effect. This paper presents an optimization to predict the influence of various parameters on springback of sheet metal in air V-bending process using Taguchi method (TM). The experimental study was conducted on DP590 sheets with plate thickness of 1 and 2 mm under different process parameters such as punch radius, die radius, die gap and punch travel. A significant level of springback parameters was further described by using the analysis of variance (ANOVA). It showed that the contribution percentage of each factor to springback was calculated to optimum level and the significant levels of entire factor were observed. The thickness of material, die width, punch travel and punch radius were found to be the most significant factor affecting springback while die radius is insignificant. 

The Backing Bar Role in Heat Transfer on Aluminium Alloys Friction Stir Welding

2010 ◽  
Vol 636-637 ◽  
pp. 459-464 ◽  
Author(s):  
M.J.C. Rosales ◽  
N.G. Alcantara ◽  
Jorge Santos ◽  
R. Zettler
Keyword(s):  
Heat Transfer ◽  
Friction Stir Welding ◽  
Aluminium Alloys ◽  
High Strength Steels ◽  
High Strength ◽  
Advanced Materials ◽  
Mechanical Degradation ◽  
Great Effort ◽  
Friction Stir ◽  
Advanced High Strength Steels

Although new structural and advanced materials have been used in the automotive and aircraft industries, especially lightweight alloys and advanced high strength steels, the successful introduction of such materials depends on the availability of proven joining technologies that can provide high quality and performance joints. Solid-state joining techniques such as Friction Stir Welding (FSW) are a natural choice since their welds are produced at low temperatures, so the low heat input provides limited, slight distortion, microstructural and mechanical degradation. Great effort has currently been devoted to the joining of Al-Cu-Mg and the Al-Mg-Si alloys because of their high strength, improved formability, and application in airframe structures. FSW is a continuous, hot shear, autogenous process involving a non-consumable and rotating tool plunged between two abutting workpieces. The backing bar plays an important role in heat transfer from stir zone (SZ), which can influence the weld microstructure as well as the consolidation of material in the root of the join. This study aims at investigating issues concerning heat generation, within the SZ of friction stir welded aircraft aluminium alloys.

An Experimental-Numerical Method to Determine the Plastic Work Converted into Heat Applied on AHSS

2016 ◽  
Vol 1140 ◽  
pp. 51-58
Author(s):  
Christian Bonk ◽  
Milan Vucetic ◽  
Anas Bouguecha ◽  
Bernd Arno Behrens
Keyword(s):  
Heat Transfer ◽  
High Strength Steels ◽  
Strain Range ◽  
High Strength ◽  
Experimental Tests ◽  
Element Model ◽  
Tensile Specimen ◽  
Heat Transfer Model ◽  
Plastic Work ◽  
Transfer Model

In this Study a Heat Transfer Model in Combination with Experimental Tests is Used to Determine the Portion of Plastic Work that is Converted into Heat (also Known as the Taylor-Quinney Coefficient, Inelastic Heat Fraction or IHF and Generally Noted β) during the Deformation of Two Modern Automotive Advanced High Strength Steels (AHSS) DP600 and DP1000. Therefore, Uniaxial Tension Tests were Performed under Vacuum in a Deformation-Dilatometer and the Temperature was Captured by Fine-Wire Thermocouples on Three Different Points on the Surface of the Tensile-Specimen during the Plastic Deformation. Afterwards, a Heat Transfer Model was Used to Calculate the Heat Loss at the Points of the Temperature Measurements and they were Accounted in the Final Energy Balance to Determine the Fraction of Plastic Work Converted to Heat. the Results Show that the Fraction of Plastic Work Converted into Heat is Decreasing from 1 to 0.21 over a Tensile Strain Range of 0 to 0.18. Finally, a Finite Element Model of the Tensile Test was Used to Show the Improvement of the Determined Factor in the Calculation of the Temperature Field Compared to the Classical Assumption that β Equals to 0.9.

Effect of Inclination Angle and Flow Rate on the Heat Transfer During Bottom Jet Cooling of a Steel Plate

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Noel L. Chester ◽  
Mary A. Wells ◽  
Vladan Prodanovic
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Inclination Angle ◽  
Steel Plate ◽  
High Strength Steels ◽  
Jet Impingement ◽  
High Strength ◽  
Heat Extraction ◽  
Flow Rates ◽  
Jet Cooling

The heat transfer that occurs during bottom water jet impingement on a hot steel plate has been investigated in terms of the effect inclination angle and flow rate. This research was carried out to develop quantitative knowledge of the heat transfer, which occurs on the runout table, a crucial component in the hot rolling production of advanced high strength steels. Industrially produced hot-rolled steel samples were instrumented with numerous subsurface thermocouples installed close to the quench surface. The experimental measurements were used in conjunction with an inverse heat conduction (IHC) model to quantify boiling characteristics as well as heat extraction histories for the different nozzle inclination angles and flow rates. It was found that, as nozzle inclination angle increased, the degree of asymmetry of the cooled region on the surface of the sample was increased and the overall rate of heat extraction decreased. The angle of inclination had a significant effect on overall heat extraction; a vertical nozzle was the most efficient from a perspective of heat transfer under the nozzle. As expected, as flow rates increased, the amount of heat energy extracted increased for all the conditions studied, regardless of the nozzle inclination.

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