Mechanical Properties and Microstructures of Ferritic-Rolled High-Strength Interstitial-Free (IF) Steel Sheets

2010 ◽  
Vol 97-101 ◽  
pp. 416-419 ◽  
Author(s):  
Wei Min Guo ◽  
Zuo Cheng Wang ◽  
Sheng Liu ◽  
Li Bin Song
Keyword(s):  
Mechanical Properties ◽  
Great Influence ◽  
High Strength ◽  
Processing Parameters ◽  
Interstitial Free ◽  
If Steel ◽  
Deep Drawability ◽  
Steel Sheets ◽  
High Strength If Steel ◽  
Save Energy

High-strength IF steel sheet has increasingly attracted more attention of steelmakers in recent years as it has the potential to lighten the weight of automobiles and save energy and lower the production cost. In this paper, the effect of processing parameters on microstructures and mechanical properties especially deep drawability of ferritic-rolled P-added high strength Ti-stabilized IF steels were investigated and the precipitates in the steels were also analyzed. The results show that lubricant condition has great influence on the r-value and deep drawability of high-strength IF steels. And with the decrease of rolling temperature in ferrite region, the deep drawability of steels is improved.

Microtexture Study of Warm-Rolled High Strength Interstitial-Free (IF) Steel Sheets

2011 ◽  
Vol 682 ◽  
pp. 71-74
Author(s):  
Cai Nian Jing ◽  
Ming Gang Wang ◽  
Xi Jun Liu ◽  
Qi Zhong Tan ◽  
Zuo Cheng Wang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
High Strength ◽  
Interstitial Free ◽  
If Steel ◽  
Boundary Character ◽  
Deep Drawability ◽  
Grain Boundary Character ◽  
High Strength If Steel

Interstitial-free (IF) steel has excellent deep-drawability and was used widely in automotive industry. High strength IF-steel is that some phosphorus was put in common IF-steel to improve its strength without destroying the deep-drawability [1]. Microstructure and grain boundary character strongly affect the deep-drawability of high strength IF-steel, it is an obligatory task to test those characters. The technique of Electron Backscatter Diffraction (EBSD) can reveal the microtexture and detailed orientation distribution of grains from a single EBSD map, as a powerful instrument, EBSD was used widely in materials research from last decade [2]. Many researches have been focused on the texture evolution and recrystallization phenomena of high strength IF-steels [3,4], but the microtexture and grain boundary characters of warm-rolled high strength IF-steels was not fully investigated. The present study was aimed at researching the microtexture characters of a commercial high strength IF-steels under different warm-rolled temperature using EBSD technique, the microstructure and grain boundary character were analyzed systemically, and the relationship between the microstructure and deep-drawability was discussed.

Precipitation Behavior of Warm-Rolled Ti-Stabilized Interstitial-Free (IF) Steel Sheets

2007 ◽  
Vol 353-358 ◽  
pp. 1653-1656 ◽  
Author(s):  
Fu Tao Han ◽  
Zuo Cheng Wang ◽  
Cai Nian Jing ◽  
Wen Ping Zhang
Keyword(s):  
Texture Evolution ◽  
Great Influence ◽  
High Strength ◽  
Recrystallization Annealing ◽  
Interstitial Free ◽  
If Steel ◽  
Precipitation Behavior ◽  
Steel Sheets ◽  
Energy Dispersion Spectrometer ◽  
Transmission Electron

Precipitates have great influence on the recrystallization, texture evolution and thus the final mechanical properties of the Interstitial-Free (IF) steel sheets, however, very few studies have dealt with the precipitation behavior of IF steels warm rolled in ferrite region. In the present work, the precipitate characteristics (type, morphology, size and amount) of warm-rolled ordinary Ti-stabilized Interstitial-Free (Ti-IF) steel and p-added high-strength Ti-IF steel were investigated by Transmission Electron Microscope (TEM) and Energy Dispersion Spectrometer (EDS). The results show that most precipitates in warm-rolled ordinary Ti-IF steels are TiN, TiS, Ti4C2S2 and TiC. Besides these precipitates, a great amount of FeTiP precipitates exist in warm-rolled P-added high-strength Ti-IF steel. The precipitation of FeTiP retards the migration of grain boundary in the recrystallization annealing, so the {111} texture and thus deep drawability of warm-rolled high-strength Ti-IF steel is deteriorated.

Influence of Boron on Mechanical Properties and Microstructures of Hot-Rolled Interstitial Free Steel

2005 ◽  
Vol 495-497 ◽  
pp. 537-542 ◽  
Author(s):  
S.I. Kim ◽  
Shi Hoon Choi ◽  
Yeon Chul Yoo
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Recrystallization Temperature ◽  
Interstitial Free ◽  
If Steel ◽  
Softening Behavior ◽  
Axial Tensile ◽  
Dynamic Softening ◽  
Work Hardening Rate ◽  
Hot Rolled

This paper examines an effect of boron (B) on dynamic softening behavior, mechanical properties and microstructures for Nb-Ti added high strength interstitial free (IF) steel. For this purpose, IF steels containing 0ppm B, 5ppm B and 30ppm B were chosen. Continuous cooling compression test was performed to investigate dynamic softening behavior. Mechanical properties and microstructures of pilot hot-rolled IF steel sheet were analyzed by uni-axial tensile test and electron back-scattered diffraction (EBSD). It was found that no-dynamic recrystallization temperature (Tndrx) which can be determined from the relationship between flow stress and temperature is a constant of 955oC for all IF steels. However, an addition of B into IF steels increases work hardening rate at the temperature below Tndrx. It was also verified that B retards phase transformation of austenite into ferrite. EBSD analysis revealed that absence of B induces fine ferrite grain size and many high angle grain boundaries.

Effect of Processing Parameters on Properties and Microstructures of Warm-Rolled Interstitial-Free (IF) Steel Sheets

2005 ◽  
Vol 297-300 ◽  
pp. 477-481 ◽  
Author(s):  
Zuo Cheng Wang ◽  
Cai Nian Jing ◽  
Yun Li ◽  
Fu Tao Han
Keyword(s):  
Deep Drawing ◽  
Production Cost ◽  
Steel Sheet ◽  
Processing Parameters ◽  
Interstitial Free ◽  
If Steel ◽  
Precipitate Morphology ◽  
Steel Sheets ◽  
Production Processes ◽  
Lower Production

In order to simplify production processes and to lower production cost of thicker coldrolled IF steel sheets for deep drawing applications, a new warm-rolled IF steel sheet was developed in our lab through hot-rolling in high-temperature ferrite range. In this paper, effect of processing parameters on properties, microstructures and precipitate morphology of warm-rolled IF steel sheets was investigated. It is found that firstly, good deep drawing properties and favorable textures were achieved as steels were warm-rolled in good lubricant condition. Secondly, most precipitates in steels were TiS, TiC, TiN and Ti4C2S2.

Research on the Microstructure and Properties of Coating on Galvannealed High Strength IF Steel

2014 ◽  
Vol 941-944 ◽  
pp. 1606-1611
Author(s):  
Chuan Wang ◽  
Hua Xiang Teng ◽  
Yong Lin Kang
Keyword(s):  
Corrosion Resistance ◽  
High Strength ◽  
Interstitial Free ◽  
If Steel ◽  
Main Constituent ◽  
Microstructure And Properties ◽  
Fe Content ◽  
Δ Phase ◽  
Coating Microstructure ◽  
High Strength If Steel

The microstructure, formability and corrosion resistance characters of industrially produced galvannealed coatings on high strength interstitial free (IF) steel with different galvannealing temperature have been investigated. With the galvannealing temperature increases, the Fe content of coating is increase, and the powdering resistance gets weaker while the corrosion resistance gets better. The coating microstructure consisting of a δ phase as the main constituent with a ζ layer on the top surface provides a good powdering resistance. The compact δ and Γ phases are good for the corrosion resistance of coating

Experimental investigation on resistance spot welding of dissimilar weld joints

2020 ◽  
pp. 095440892096835
Author(s):  
Rohit Verma ◽  
Kanwer Singh Arora ◽  
Lochan Sharma ◽  
Rahul Chhibber
Keyword(s):  
Welding Process ◽  
High Strength ◽  
Dynamic Resistance ◽  
Interstitial Free ◽  
Resistance Spot ◽  
Dissimilar Weld ◽  
Steel Sheets ◽  
Weld Joints ◽  
Resistance Spot Weld ◽  
Weld Current

In the present study, galvanized High Strength Interstitial Free (HIF) steel sheets, and Dual Phase (DP780) steel sheets were used for the investigations. Resistance spot weld joints were fabricated between dissimilar steel sheets. The variation in dynamic resistance (DR) with the change in welding process parameters such as weld current, weld time and electrode force were used for establishing the range of adequate weld nugget formation parameters. Effect of these parameters over tensile strength, nugget diameter and the observed failure mode was studied using one factor at a time (OFAT) approach. Microstructure and hardness of parent metal, fusion & HAZ region has also been studied.

scholarly journals Effect of Rare Earth Ce on Deep Stamping Properties of High-Strength Interstitial-Free Steel Containing Phosphorus

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1473
Author(s):  
Hao Wang ◽  
Yanping Bao ◽  
Chengyi Duan ◽  
Lu Lu ◽  
Yan Liu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Rare Earth ◽  
High Strength ◽  
Rolling Process ◽  
P Element ◽  
Second Phase ◽  
Strengthening Effect ◽  
Interstitial Free ◽  
If Steel

The influence of rare earth Ce on the deep stamping property of high-strength interstitial-free (IF) steel containing phosphorus was analyzed. After adding 120 kg ferrocerium alloy (Ce content is 10%) in the steel, the inclusion statistics and the two-dimensional morphology of the samples in the direction of 1/4 thickness of slab and each rolling process were observed and compared by scanning electron microscope (SEM). After the samples in each rolling process were treated by acid leaching, the three-dimensional morphology and components of the second phase precipitates were observed by SEM and energy dispersive spectrometer (EDS). The microstructure of the sample was observed by optical microscope, and the grain size was compared. Meanwhile, the content and strength of the favorable texture were analyzed by X-ray diffraction (XRD). Finally, the mechanical properties of the product were analyzed. The results showed that: (1) The combination of rare earth Ce with activity O and S in steel had lower Gibbs free energy, and it was easy to generate CeAlO3, Ce2O2S, and Ce2O3. The inclusions size was obviously reduced, but the number of inclusions was increased after adding rare earth. The morphology of inclusions changed from chain and strip to spherical. The size of rare earth inclusions was mostly about 2–5 μm, distributed and dispersed, and their elastic modulus was close to that of steel matrix, which was conducive to improving the structure continuity of steel. (2) The rare earth compound had a high melting point. As a heterogeneous nucleation point, the nucleation rate was increased and the solidification structure was refined. The grade of grain size of products was increased by 1.5 grades, which is helpful to improve the strength and plasticity of metal. (3) Rare earth Ce can inhibit the segregation of P element at the grain boundary and the precipitation of Fe(Nb+Ti)P phase. It can effectively increase the solid solution amount of P element in steel, improve the solid solution strengthening effect of P element in high-strength IF steel, and obtain a large proportion of {111} favorable texture, which is conducive to improving the stamping formability index r90 value.

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