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Annealing Response of Cold-Rolled Vanadium Microalloyed Sheet steels

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Journal of Iron and steel research International 2011年第S1期18卷 404-411页

作者： John G Speer David K Matlock Robert J Glodowski A dvanced steel processing and products research center Colorado School of MinesGoldenColorado USA East Metals (North America) LLCPittsburghPAUSA

Vanadium microalloying is widely employed in hot-rolled HSLA products;because of its relatively high solubility in austenite,vanadium plays a special role in thin-slab cast hot-rolled products where reheating is limited prior to *** cold-rolled and annealed sheet steels,vanadium technology has been employed in bake-hardenable drawing-quality steels,and in HSLA *** studies have investigated the continuous and batch annealing response of vanadium-containing cold-rolled HSLA steels,with an emphasis on aluminum and nitrogen variations (because of the special importance of nitrogen in vanadium microallyed steels,and interesting interactions between vanadium,aluminum and nitrogen).The present contribution reviews some key aspects of vanadium-microalloyed coldrolled sheet steels,and highlights the results of selected studies showing the influence of steel composition and processing.

关键词： Microalloying vanadium,bake-hardening cold rolled sheet steel

Nb-Microalloying in Next-Generation Flat-Rolled steels

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Nb-Microalloying in Next-Generation Flat-Rolled Steels

Phase transformation behavior of a hot-rolled,titanium microalloyed steel during heating and continuous cooling

“第十届中国钢铁年会”暨“第六届宝钢学术年会”

作者： SPEER John G ARAUJO Ana L MATLOCK David K DE MOOR Emmanuel advanced steel processing and products research center Colorado School of Mines

Extensive efforts are underway worldwide to develop new steels with substantial fractions of retained austenite, for lightweight automobile manufacturing and other applications requiring improved combinations of strength and formability. It is likely that microalloying can provide product enhancements in these emerging products, such as Q＆P, TBF, medium-Mn TRIP, etc. And this paper examines the expected behavior of niobium using inferences based on published AHSS literature and principles of *** benefits of Nb in terms of microstructure refinement and precipitation strengthening have been reported, and increased retained austenite levels are shown here in Q＆P hot-rolling simulations. The potential influences of Nb are complex due to the sensitivity of Nb dissolution and precipitation to chemical composition and processing;differences in the expected role of Nb are pointed out with respect to different product forms produced via hot-rolling or annealing after cold-rolling, and microstructures with or without substantial quantities of primary ferrite. Some issues that warrant further examination are identified, as a deep understanding of Nbmicroalloying and other fundamental behaviors will be needed to optimize the performance of these next-generation steels.

关键词： niobium high strength steel Q&P sheet plate

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Baosteel Technical research 2018年第4期12卷 28-32页

作者： LIU Gang John G SPEER Caleb A FELKER research Institute Baoshan Iron & Steel Co.Ltd. advanced steel processing and products research center Colorado School of Mines1500 Illinois St.

The critical transformation temperatures,A_(c1) and A_(c3),of a hot-rolled low-carbon titanium microalloyed steel were determined as a part of an examination of its phase-transformation behavior. Austenite decomposition during the continuous cooling of the titanium microalloyed steel was studied by heating it to 1 250 ℃,cooling it to 880 ℃,holding for 2 s,and then cooling it to room temperature at different cooling rates. The transformation kinetics( CCT curve) was characterized as well.

关键词： microalloyed steel hot-rolled precipitation phase transformation

Effect of intercritical annealing on microstructure,mechanical properties,and work-hardening behavior of ultrahigh-strength dual-phase steels with different silicon contents

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Baosteel Technical research 2018年第4期12卷 1-8页

作者： LI Wei1 John G SPEER ZHU Xiaodong LI Wei school of Materials Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China research Institute Baoshan Iron &Steel Co.Ltd.Shanghai 201900China State Key Laboratory of Development and Application Technology of Automotive steels (Baosteel) Shanghai 201900China advanced steel processing and products research center Colorado School of Mines1500 Illinois St.GoldenColorado 80401USA

In this study,three kinds of dual-phase(DP) steels were used to investigate the influence of silicon content and intercritical annealing temperature on their microstructures,mechanical properties,and work-hardening behaviors. By adding silicon and matching the critical annealing temperature,a new DP steel(1.0Si and intercritically annealed at 790 ℃) that exhibits an excellent combination of ultrahigh strength and adequate ductility was obtained. Variations in the strength,elongation,and fracture mechanism of the specimens with respect to different intercritical annealing temperatures were correlated to microstructural features. With an increase in the silicon content,there is no significant change in the martensitic band structure or ferrite morphology. At the same annealing temperature,the yield strength and yield strength ratio of the specimens decreased,but at different annealing temperatures,the tensile strength was reduced. The Hollomon analysis results indicate that the workhardening behavior obeys a two-stage work-hardening mechanism. With an increasing intercritical annealing temperature,the "transition strain"shifts to the left,and with an increasing silicon content,the "transition strain"shifts to the right. The surface exhibits ductile fractures characterized by a high density of microvoid dimples. With an increase in the silicon content,the average dimple size on the fracture surface decreases and the plasticity of the material increases.

关键词： dual-phase steel thermomechanical processing microstructure mechanical

Ultra-high strength sheet steel property developments

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Baosteel Technical research 2010年第S1期4卷 45-页

作者： John G SPEER Emmanuel De MOOR David K MATLOCK advanced steel processing and products research center colorado school of mines GoldenCO80401USA

Conventional advanced high strength steels(AHSS) such as dual-phase,TRIP and martensitic sheet products have undergone extensive development and substantially increased implementation in automobile structures over the past few *** are now underway to extend these improvements and develop steels with even greater strengths and formability.A variety of alloy/process/microstructure/property approaches aimed at next generation AHSS properties are highlighted *** approach involves the quenching and partitioning process,originally conceived at the colorado school of mines,but now being investigated around the global automotive steel development *** implementation efforts are underway,and new results demonstrate the capability to obtain ultra-high strength levels with usable *** the field more broadly,it appears that several approaches are converging,and it is likely that additional attention will continue to be placed on expanding the allowable range of austenite stabilizing elements.

关键词： AHSS sheet steel Q & P

Development of microalloyed steels for high temperature carburizing

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Baosteel Technical research 2010年第S1期4卷 86-页

作者： David K MATLOCK John G SPEER Steven G JANSTO Marcos STUART advanced steel processing and products research center colorado school of mines GoldenColorado USA CBMM-Reference Metals Bridgeville PA CBMM Sao Paulo Brasil

The potential for use of microalloy additions to suppress abnormal austenite grain growth and produce steels with enhanced bending fatigue resistance after high temperature vacuum carburizing was investigated in a series of Ti-modified SAE 8620 steels with w(niobium) additions up to 0.1%.Results are considered from a series of papers at the advanced steel processing and products research center on the effects of Nb content,heating rate, rolling history,and processing temperature on the evolution of austenite grain structures in carburizing steels. Emphasis is placed on understanding the effects of alloying and processing on each stage in the annealing process including the as received laboratory rolled conditions,during the onset of carburizing after annealing at different heating rates,and after annealing for various times at carburizing temperatures up to 1 100℃.Heating rate to the carburizing temperature was shown to be an influential variable and suppression of abnormal grain growth was dependent on the development of a critical distribution of fine NbC precipitates,stable at the austenitizing *** importance to industrial carburizing practice of heating rate effects on precipitates and austenite grain size evolution are discussed and correlated to selected data on fatigue performance.

关键词： heat treating microalloying carburizing niobium abnormal grain growth

Design Details for the Development of Flux-Related Arc Welding Consumables

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Design Details for the Development of Flux-Related Arc Weldi...

Analysis and Control on Fracture of 20Mn2A High Tensile steel for Round Link Chain

第十次全国焊接会议

作者： Stephen Liu center for Welding Joining and Coatings Research Department of Metallurgical and Materials Engineering Colorado School of Mines Golden Colorado 80401 U.S.A.

＜正＞ Modern materials and designs have led to both innovative and bold welded structures that require enhanced properties and performance from the welded joints. As such, there is also a greater need for higher quality and tailored welding consumables. Experience accumulated in the past century clearly shows that development of quality consumables is not entirely empirical and always requires good understanding of the fundamentals of welding processes and materials. Despite the recent progress in mathematical modeling of weldments, as evidenced by a wealth of publications in the past decade, the same level of development has not happened in the area of flux-related welding processes. Because of the complexity of the slag-metal interactions, many levels of details on processing and transformations have yet to be incorporated in most modeling effort. Thus, flux/slag/weld metal interaction must be better understood in order to design the 21st Century flux-containing consumables for are welding. To demonstrate the need for fundamental understanding of flux-weld metal relationships, this paper will summarize several recent examples of innovative approaches in designing flux-containing are welding consumablesAs the strength of a steel weld metal increase to match the higher strength base metals, hydrogen management in the welded joints becomes more critical. Consumables with flux ingredients, capable of minimizing hydrogen in the arc plasma and in the molten weld pool, must be designed for high strength steel weld metals. One such approach using fluoride additions in the flux was discussed to examine the feasibility of hydrogen minimization in the *** wet welding, often used in the maintenance of marine structures, typically results in high weld metal diffusible hydrogen. Welding consumables with high oxygen potential developed in the last decade were able to lower diffusible hydrogen content to less than 20 ml/100g, a level found in many surface welds produc

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Journal of Iron and steel research International 2011年第S1期18卷 898-902页

作者： CAO Shu-wei 1,2,KANG Yong-lin 1,3,ZHAO Xian-ping 2,YANG Chang-chun 1 (1.school of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China 2.Technology center of Anyang Iron & steel Group Co.,Ltd.,Anyang 455004,Henan,China 3.State Key Laboratory for advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China) Univ Sci & Technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China Anyang Iron & steel Grp Co Ltd Ctr Technol Anyang 455004 Henan Peoples R China Univ Sci & Technol Beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

Based on the phenomenon of brittle fracture occurred during tensile test for 20Mn2A high strength circular chain used in coal mines,the fracture property is regarded as intercrystalline brittle one after macroscope observation and metallographic *** is analysed that the intercrystalline brittle fracture is due to high tempering temperature and limited processing site where final products are piled together after heat treatment,which lead to a lower cooling rate of internal chain,with Si,Mn and P etc elements segregating and enriching in the austenite grain boundary and forming high tempering *** these circular chains are tempered again for one hour at 670℃,and oil-cooled rapidly,due to the reversibility of high temper brittleness for structural alloy steel,the high temper brittleness can be eliminated and products are completely qualified after tensile inspection.

关键词： high strength circular chain metallographic examination brittle fracture high tempering brittleness improvement measures