S.K.He
,
G.S. Wang and S.N. Wang(Beijing institute of Aeronautical Materials
,
Beijing 100095
,
China Manuscript received 26 August 1996)
金属学报(英文版)
Influences of sulphureous impurity and micro-shrinkage on hydrogen assisted cracking (HAC) and fracture behavior of the super-strength low-alloy steel 40CrMnSzMo VA have been studied in this paper.By way of scanning electron microfractography (SEM)and electron probe microanalyser to investigate the fractography of material constantly strained to failure, it was found that the microscopic segregation of sulphureous impurity and micro-shrinkage not only increased strongly the susceptibility to hydrongen embrittlement (HE), but also made the HAC to initiate preferably in such regions with the assistant of stress induced diffusion of hydrogen. The microscopic observation revealed that the steel has commonly intergranular (IG) and quasi-cleavage (QC)features around the segregation of sulphureous impurity and micro-shrinkage for their strong effects of irreversible traps for hydrogen.
关键词:
:micro-shrinkage
,
null
,
null
,
null
胡义华
,
刘美希
,
陈丽
,
王小涓
,
储焰南
,
曹德兆
量子电子学报
doi:10.3969/j.issn.1007-5461.2001.04.008
本文在流动余辉装置上,研究了亚稳态He(23S)原子与N2H4分子碰撞传能,观察到了激发态产物NH(A3II→X3∑+)、NH(c1II→a1△)、NH2(A2A1→X2B1)的发射光谱,由相对光谱强度求得了形成各产物的通道比;分析NH(A3II,v＇=0)的转动分辨谱的结果表明,v＇=0能级上的转动布居是"双模”分布,激发态产物NH(A)、NH2(A)的形成机理可能是: He(23S)+N2H4→N2H4*→NH(A)+NH2(A)+H.
关键词:
碰撞传能
,
化学发光
,
NH(A3Ⅱ)的发射光谱
ZHANG Lei WANG Peixuan TAO Rong MA Ruzhang ZHANG Guoguang University of Science and Technology Beijing
,
Beijing
,
China professor
,
Department of Materials Physics.University of Science and Technology Beijing.Beijing 100083
,
China
金属学报(英文版)
Nucleation and growth of He bubbles at different annealing temperatures T≤1023 K in stain- less steels HR-2 and SS321,implanted with He~+(40-70 keV.1×10~(16)-6× 10~(17) He~+/cm~2),were ohserved under TEM.T=0.45T_m seems to be a transition temperature.The He bubbles continue mainly their nucleation at 0.3T_m< T<0.45T_m,and grow predominantly at T≥0.45T_m,due probably to migration and coalescence by surface diffusion of metal atoms around the bubbles.The apparent activation energies for the growth are found to he 0.41 and 0.31 eV for HR-2 and SS321 respectively.The bubble density in HR-2 is greater than that in SS321 within whole measuring temperature range,and the onset temperature of rapid swelling is also higher.It is believed that the resistance of HR-2 to He is superior to that fo SS321.
关键词:
stainless steel
,
null
,
null
,
null
,
null
材料科学技术（英文）
Creep testing was conducted on K40S alloy. The detailed creep deformation and fracture mechanisms under constant load were studied. The results show that the stress exponent ranges between 7 and 14.4 at elevated temperature 973similar to1173 K, and that the activation energy is approximately 449.1 kJ/mol. During creep, the grain boundary sliding cut off primary carbides at the boundary, generating the "O" model cracks. The creep failure mode of K40S alloy is transgranular ductile and cracks originate at the primary carbides. A long carbide and matrix interface is often a preferential path for crack propagation. The creep mechanism is discussed in light of the creep microstructure, the stress exponent and the activation energy.
关键词:
K40S alloy;creep;fracture;crack propagation;activation-energies;superalloy;term
王宝奇
,
谷南驹
,
郭素珍
,
马晓莉
金属学报
利用Bain点阵对应对K-S模型的晶格改建过程进行了严密的数学描述.对于不同的马氏体正方度,提出了计算第一切变、第二切变及晶格调整的计算依据,并给出了普遍的计算公式.以Fe-1.4C和纯铁为例,计算了马氏体相变的点阵畸变.进一步分析表明,K-S模型实质是Bain模型的旋转.计算的结果与实测的取向关系相符合.
关键词:
K-S模型
,
null
,
null
Corrosion Science
Arc ion plating had been employed on a cobalt-base superalloy K40S to deposit a NiCrAlYSi coating to improve its oxidation resistance at 1323-1423 K in air. The K40S superalloy had poor oxidation resistance because a non-protective and easy spalling surface oxides scale mixed of Cr2O3 and CoCr2O4 was formed on its surface. After coated with NiCrAlYSi coating, a dense and protective alpha-Al2O3 scale was formed on the coating and excellently improved its oxidation resistance. Inter-diffusion obviously occurred between the coating and the substrate K40S superalloy in oxidation process, which resulted from Co atoms in K40S outwards diffused. A richen Cr and W carbides inter-diffusion layer was formed, which could acted as a diffusion barrier that barred Al atoms in coating inwards diffusion. Though the NiCrAlYSi changed into NiCoCrAlYSi during oxidation process, it still possessed a good oxidation resistance and. had a considerable long-term life. (C) 2008 Elsevier Ltd. All rights reserved.
关键词:
cobalt-base superalloy K40S;NiCrAlYSi coating;arc ion plating;high;temperature oxidation;inter-diffusion;aluminide coatings;cyclic oxidation;alloys
