Development in oxide metallurgy for improving the weldability of high -strength low-alloy steel-Combined deoxidizers and microalloying elements

The mechanisms of oxide metallurgy include inducing the formation of intragranular acicular ferrite(IAF)using micron-sized inclusions and restricting the growth of prior austenite grains(PAGs)by nanosized particles during welding.The chaotically oriented IAF and refined PAGs inhibit crack initiation and propagation in the steel,resulting in high impact toughness.This work summarizes the com-bined effect of deoxidizers and alloying elements,with the aim to provide a new perspective for the research and practice related to im-proving the impact toughness of the heat affected zone(HAZ)during the high heat input welding.Ti complex deoxidation with other strong deoxidants,such as Mg,Ca,Zr,and rare earth metals(REMs),can improve the toughness of the heat-affected zone(HAZ)by re-fining PAGs or increasing IAF contents.However,it is difficult to identify the specific phase responsible for IAF nucleation because ef-fective inclusions formed by complex deoxidation are usually multiphase.Increasing alloying elements,such as C,Si,Al,Nb,or Cr,con-tents can impair HAZ toughness.A high C content typically increases the number of coarse carbides and decreases the potency of IAF formation.Si,Cr,or Al addition leads to the formation of undesirable microstructures.Nb reduces the high-temperature stability of the precipitates.Mo,V,and B can enhance HAZ toughness.Mo-containing precipitates present good thermal stability.VN or V(C,N)is ef-fective in promoting IAF nucleation due to its good coherent crystallographic relationship with ferrite.The formation of the B-depleted zone around the inclusion promotes IAF formation.The interactions between alloying elements are complex,and the effect of adding dif-ferent alloying elements remains to be evaluated.In the future,the interactions between various alloying elements and their effects on ox-ide metallurgy,as well as the calculation of the nucleation effects of effective inclusions using first principles calculations will become the focus of oxide metallurgy.

LIRR "R&D and Industrialization of High PerformanceFunctional Refractories for Metallurgy New Technology" Project Gained Fund Support

Checked by Henan Province Development and Relbrm Commission and Henan Province MunicipalFinance （）ffice, the “R ＆ I） and Industrialization of High Performance Functional Refractories for Metallurgy New Technology” project declared by 1,1RR gained a special fund support on self-renovation and products structure adjustment. The project will realize the technology integration and industriali-zation of key refractories including purging component, metering nozzle and toil and belt continuous casting nozzle, etc. through building high performance functional refractories production lines for metallurgy new technology.

Brief Outline of the Metallurgy Department of Kunming Institute of Technology

The metallurgy department of Kunm-ing Institute of Technology,with its empha-sis on nonferrous metallurgy,is one of themajor academic and technical centres underthe China National Nonferrous Metals In-dustry Corporation(CNNC).The province of Yunnan,of whichKunming is the capital city,is very rich withresources of nonferrous metals,such as

Investigation on the Synthesis Mechanism of β-FeSi_2 Prepared by Pulsed Laser Deposition

The FeSi2 target alloy was fabricated by conventional powder metallurgy technology, and then, β-FeSi2 thin films was successfully prepared by pulsed laser deposition （PLD）. X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM） were used to characterize the structure, composition, and their changes in the process of β-FeSi2 preparation. In addition, a laser sintering process was also employed to prepare FeSi2 alloy. The analysis of radiation heat transfers in different-sized FeSi2 melt indicates that the cooling rate of the melt depends on the size, i.e., the cooling rate of the micron sized melt is 103 times greater than that of the millimeter-sized melt. The product a-FeSi2 by laser sintering and β-FeSi2 by PLD reveals the different phase transition process in crystallization of millimeter-sized and micron-sized （or submicron-sized） FeSi2 melt. The results of PLD preparation process shows that β-FeSi2 could be prepared through a liquid-phase sintering, followed by a rapid cooling.