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Huai’an, China

Lei Y.,Jiangsu University | Lei Y.,Jiangsu Province Key Laboratory of High End Structural Materials | Gong C.,Jiangsu University | Luo Y.,Jiangsu University | And 2 more authors.
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | Year: 2014

The 1.3 mm thick plate of ODS high temperature alloy MGH956 was TIG welded with fillers containing different B4C (0, 0.25 and 0.5 mass%), then the effect of B4C content on the microstructure and mechanical properties of the weld joints was investigated. The results show that the microstructure of the weld metal with B4C exhibits mainly equiaxed grains, which are fine and uniform, without significant agglomeration of oxide dispersoids, while the strengthening particulates of the alloy distribute in both grains and grain boundaries. The microstructure of weld joint was finer as the filler with B4C content in a range from 0.25 to 0.5 mass%. However nearly almost the strengthening particulates of the alloy concentrate in the grain boundaries but disappear in the grains for the weld joints by filler with 0.5% B4C. The tensile strength of the weld joints firstly increases and then decreases when the B4C content of the fillers ranged from 0% to 0.5 mass%, but their toughness decreases with the induce of B4C. The tensile strength of the weld joint with filler material containing 0.25% B4C is the highest i.e. 630 MPa, reaching 87.5% of the parent material. The fractured surface exhibited characteristics of brittle fracture. © Copyright. Source


Lei Y.-C.,Jiangsu University | Lei Y.-C.,Jiangsu Province Key Laboratory of High End Structural Materials | Luo Y.,Jiangsu University | Gong C.-C.,Jiangsu University | And 2 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2014

It was easy for alloying elements and strengthening particles in MGH956 alloy to burning and aggregating during TIG in -situ welding. In this paper, effects of heat treatment on MGH 956 alloys microstructure TIG in-situ alloying welded were studied. Filler material of ωV=2.0% was used in the welding process, heat preservation time was 2.0 h, temperature was 700°C, and then air cooling. After heat treated, the grain boundary aggregation was significantly reduced, more fine particles generated in the weld, which were mainly YAlO3, TiC and TiN particle demonstrated by EDS analysis, in addition, (Ti, V)C composite particles were fund. By atomic probe analysis, the segregation of element Y reduced, therefore the porosity of the weld were reduced after heat treatment, ultimately, performance of the joint was improved. Source


Lei Y.-C.,Jiangsu University | Gong C.-C.,Jiangsu University | Luo Y.,Jiangsu University | Xiao B.,Jiangsu University | And 2 more authors.
Cailiao Gongcheng/Journal of Materials Engineering | Year: 2015

The arc-ultrasonic was excited by modulating the TIG arc through high frequency and the homemade solder was filled in the weld as filler composite. The effect of arc-ultrasonic on pores, microstructures and mechanical properties of MGH956 alloy joints produced by arc-ultrasonic in-situ alloying TIG welding with different excitation current was investigated. The results show that when the excitation current is 10A, pores grow up obviously while the number of pores is reduced, moreover, the grains are coarse. When the excitation current increases to 20A, the number of pores sharply decreases, the grains are fine and uniform, and the particle reinforced phases are uniformly distributed in the weld. When the excitation current increases to 30A, the number of pores further decreases while the grains are coarsen. The tensile results indicate that the maximum tensile strength of the weld joint is achieved at an excitation current of 20A, which is 626MPa and reaches 87% of the base metal. The toughness of joints is improved obviously and the fracture surface changes from completely brittle fracture to ductile-brittle mixed fracture. ©, 2015, Beijing Institute of Aeronautical Materials (BIAM). All right reserved. Source


Yang W.,Huai Steel Special Steel Co.
Kang T'ieh/Iron and Steel (Peking) | Year: 2010

In order to study heredity of solidification structure and segregation of spring steel billet rolled, the 60Si2Mn billets with different equiaxed grain rate and segregation degree were used as experiment objects. The billets with 150mm × 150mm section were rolled into 2 round bars with 75mm and 25mm diameter separately. The mechanical properties at interior different position of rolled steel and segregation index of billets with different equiaxed grain rate were measured. The results show that the carbon segregation index in off center area where the distance to billet core exceed 21.2mm does not improved while equiaxed grain rate is increased. Porosity and light segregation existed within rolled steel and the inner mechanical property is poor relatively. Therefore central segregation and porosity of billet would inherit to rolled steel. The mechanical property and its uniformity of round bar whose diameter is 25mm is better than that of round bar whose diameter is 75mm. As a result, adding rolling reduction would lighten heredity effect of billet central segregation. Source


Xiao B.,Jiangsu University | Xiao B.,Huai Steel Special Steel Co. | Lei Y.-C.,Jiangsu University | Wu X.-D.,Jiangsu University
Key Engineering Materials | Year: 2014

The research centers on the production process of high tensile 60Si2CrVNb spring steel for long service life with reference to the production conditions. Key points of the research lies in: long fatigue life and control techniques of non-metallic inclusions in melting process. Hot treatment process of spring steel also involves with the research, aiming to increase the strength of material by fining grain size by Nb element. The results confirms to the size of non-metallic inclusions can be controlled below 10μm with adoption of technologies of LF slag control and barium microalloy treatment in steelmaking process. The tensile strength can be over 2.0GPa and the elongation can reach up to 10% in the event that the quenching temperature is900? and the tempering temperature is 410? resulting obvious increase of strength and plasticity of spring steel. ©2014 Trans Tech Publications Ltd, Switzerland. Source

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