Chinese Academy of Sciences

Dalian University of Technology

Institute of Metal Research Academy of Sciences

Dianzhong Li

Yiyi Li

Bin Xu

Hongwei Liu

Paixian Fu

Lijun Xia

Pei Wang

Yikun Luan

Mingyue Sun

Xiaoqiang Hu

Hanghang Liu

Chaoyun Yang

Yong Zhao

Renke Kang

Yang Liu

Jiang Guo

Peng Liu

Zhaocheng Wei

Hang Liu

Longzhe Zhao

Zhuji Jin

A method for evaluating a surface cleanliness oriented toward additive forging of a metal substrate employs weight coefficients corresponding to oil contaminants, particles and chips. Contamination scores of different contaminants are determined separately by different methods, and a surface cleanliness thereof is characterized in a quantitative manner by calculating the sum of the product of the weight coefficient and the contamination score of each contaminant. Further, an accurate and systematic method for evaluating a surface cleanliness employs weight coefficient of each contaminant determined based on a degree of adverse influence of the contaminant on the interface bonding of a substrate. Different detection methods are used for different contaminants. The contamination score of each contaminant is determined by the sum of the product of the weight coefficient and the contamination score of the corresponding contaminant, the comparison relationship is thus established, a cleanliness level is finally determined.

Method for evaluating substrate surface cleanliness oriented to additive forging

A control process of inclusions in ultra-clean rare earth steel, wherein the content of rare earth elements REM in the ultra-clean rare earth steel, the total oxygen content T[O]m, the total sulfur content T[S]m in the steel, and the total oxygen content T[O]r in a rare earth metal or alloy added to the steel are controlled to satisfy the following formula: −500<REM−(m*T[O]m+n*T[O]r+k*T[S]m)<−30, where REM is the content of rare earth elements in the steel, in ppm; T[O]m is the total oxygen content in the steel, in ppm; T[O]r is the total oxygen content in a rare earth metal or alloy added to the steel, in ppm; T[S]m is the total sulfur content in the steel, in ppm; m is a first correction coefficient, with a value of 2-4.5;n is a second correction coefficient; and k is a third correction coefficient.

Ultra-clean rare earth steel and occluded foreign substance modification control method

Provided in the present application are a rare-earth microalloyed steel and a control process. The steel has a special microstructure, and the microstructure comprises a rare earth-rich nanocluster having a diameter of 1-50 nm. The nanocluster has the same crystal structure type as a matrix. The rare earth-rich nanocluster inhibits the segregation of the elements S, P and As on a grain boundary, and obviously improves the fatigue life of the steel. In addition, a rare-earth solid solution also directly affects a phase change dynamics process so that the diffusion-type phase change starting temperature in the steel changes at least to 2&#xb0; C., and even changes to 40-60&#xb0; C. in some kinds of steel, thereby greatly improving the mechanical properties thereof, and providing a foundation for the development of more kinds of high-performance steel.

Rare-earth microalloyed steel and control method

A constructing-and-forging method for preparing homogenized forged pieces comprises: preparing preformed billets: cutting off a plurality of continuous casting billets, milling and smoothing surfaces of the billets to be welded, performing vacuum plasma cleaning operation to the surfaces to be welded, stacking the plurality of billets and sealing around the surfaces in a vacuum chamber by electron beam welding; forge-welding and homogenizing the preformed billets: heating the preformed billets to a certain temperature in a heating furnace and taking the heated preformed billets out of the heating furnace, forging the preformed billets by a hydraulic press, then using three-dimensional forging to disperse the welded surfaces such that composition, structure and inclusion of the interface areas are at the same level as those of the bodies of the billets. Cheap continuous casting billets are stacked and forge welded.

Additive forging method for preparing homogenized forged pieces

Constructing-and-forging method for preparing homogenized forged pieces

A method for controlling A-shaped segregation of steel ingot. The method includes: 1) controlling a content of phosphorus in liquid steel at less than or equal to 0.005 wt. % upon tapping from an electric furnace, preventing steel slag from entering a ladle, controlling content of harmful elements at less than or equal to 100 ppm; and adding between 3 and 15 kg of calcium oxide and less than or equal to 0.5 kg of aluminum to each ton of the liquid steel; 2) pre-deoxidizing the liquid metal using vacuum carbon deoxidation; 3) de-sulfurizing, controlling content of oxygen, and controlling the content of sulfur in the liquid steel at less than or equal to 0.005 wt. %; and 4) performing vacuum degasification, controlling the total oxygen content at less than or equal to 15 ppm; and casting the steel in the presence of inert gas or in vacuum.

Method for controlling A-shaped segregation by purification of liquid steel

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Shenyang, China

Dianzhong Li