Q.A. Li
,
H.Q. Mo
,
Y.Z. Huo
,
G. Sang
,
Y.F. Chen
,
M.G. Han
,
Y.G. Chen and M.J. Tu Department of Metal Materials
,
Sichuan University
,
Chengdu 610065
,
China
金属学报(英文版)
In this paper,a simulation model for the temperature field in the solidification process and microstructure distribution is presented. Then, the result of simulation for the final microstructure distribution is compared with experiment using 10-Kg ingot of MlNi3.55Al0.3Mn0.4CO0.75 (Ml: Lanthanum-rich Mischmetal) hydrogen stor- age alloy cast in a mould, which agrees with the experiment well. Finally, in order to obtain the expected as-cast microstructure distribution of 15-Kg ingot of MlNi3.55Al0.3Mn0.4Co0.75 alloy, the size of Cu mould is optimized using the model described. The optimized mould is then made and the alloy is cast in it, the expected as-cast microstructure distribution is obtained.
关键词:
hydrogen storage alloy
,
null
,
null
,
null
Journal of Alloys and Compounds
The structural relationship between the hydride phases in Ti-Mo-H solid solution system (Mo content up to 15 at% in the alloy) during dehydrogenation process under annealing has been studied by conventional and in situ X-ray powder diffraction and transmission electron microscopy (TEM) analysis. During dehydrogenation, the saturated hydrides of the Ti-Mo alloys with fcc delta-phase structure transfer into bcc beta-phase at higher temperatures. An associated hydrogen concentration reduction for the delta-phase hydride is observed in the process. However, as the hydrogen concentrations decrease to certain values (H/M similar to 1.1-1.7), the unsaturated delta-phase formed at high temperature would become unstable at lower temperature, and transfer into a tetragonal phase (denoted the epsilon-phase here). Unlike that of the e-phase in Ti-H system, the phase transition does not occur for the saturated delta-phase with hydrogen concentration close to the stoichiometric limit. The hydrogen concentration of this epsilon-phase hydride is in between that of the tetragonal gamma and epsilon-phase in Ti-H system, but more close to the gamma-phase. The occurrence region of this epsilon-phase expands along with the increase of the Mo content in the alloys. The phase has a lattice similar to that of the e-phase in Ti-H system with corresponding fct unit-cell c/a < 1. (c) 2007 Published by Elsevier B.V.
关键词:
hydrogen storage materials;gas-solid reactions;X-ray diffraction;titanium hydride;zirconium;alloy;diffraction;deuteride;crystallography;transformation;property;neutron
Corrosion Science
The corrosion of Q235 and 5Crl/2Mo steels in synthetic refining media containing naphthenic acid and/or sulphur compounds was studied to evaluate naphthenic acid corrosion (NAC), sulphidic corrosion (SC), and their interaction. Corrosion dependencies on the test duration, temperature, total acid number (TAN) and content of sulphur compound were assessed. Specimens after NAC and SC tests were characterized by SEM/EDX, and XRD. It is found that in liquid phase of media containing only naphthenic acid and at temperature about 230 degrees C, 5Crl/2Mo and Q235 steels have almost the same NAC rate, and above 230 degrees C, 5Crl/2Mo has a higher NAC rate than Q235 has due to the higher NAC activation energy (63.2 kJ mol(-1)) of 5Crl/2Mo than that of Q235 (54.0 U mol(-1)), indicating that increasing temperature accelerates NAC rate of 5Crl/2Mo more than that of Q235. In oil containing only dimethyl disulphide, the growth of SC film follows parabolic kinetics, and the film of Q235 grows faster than that of 5Crl/2Mo while SC rate of Q235 is higher than that of 5Crl/2Mo. In oil containing both naphthenic acid and dimethyl disulphide, 5Crl/2Mo has a lower corrosion rate than Q235 has. On the basis of "naphthenic acid corrosion index" (NACI), the benefits of 5Crl/2Mo over Q235 should ascribe to that the pseudo-passive film for 5Crl/2Mo has better NAC resistance than that for Q235. This is close related to the existing of additional chromium sulphide (Cr5S8) on the pseudo-passive film of 5Crl/2Mo, in contrast with the pyrrhotite (Fe7S8) and troilite (FeS) on the film of Q235. (c) 2005 Elsevier Ltd. All rights reserved.
关键词:
naphthenic acid corrosion;sulphidic corrosion;oil refining;synergism;pseudopassive film;erosion-corrosion;crude oils;refineries
徐晋勇
,
刘燕萍
,
王建忠
,
隗小云
,
高原
,
徐重
材料热处理学报
doi:10.3969/j.issn.1009-6264.2006.01.026
对比研究了Q235钢进行双层辉光等离子Mo-Cr共渗和不同热处理工艺处理的表面层组织和性能.结果表明:Q235钢等离子Mo-Cr共渗+超饱和渗碳+淬火+深冷处理+回火的试样,表面渗层组织结构细小,碳化物分布弥散,尺寸小于1μm,表面硬度达到1600HV.摩擦磨损试验表明:Q235钢经过渗碳+淬火+低温回火、等离子Mo-Cr共渗+离子渗氮、等离子Mo-Cr共渗+超饱和渗碳+淬火+低温回火、等离子Mo-Cr共渗+超饱和渗碳+淬火+深冷处理+低温回火处理的试样的相对耐磨性分别为:1,1.32,1.6和2.74.
关键词:
Mo-Cr共渗
,
表面合金化
,
深冷处理
,
离子渗氮
,
碳化物
郭秀辉
钢铁研究
为保证莱钢Q275D热轧H型钢极限规格的-20℃冲击功值满足GB/T 700-2006要求,采用Nb微合金化结合再结晶控轧工艺试制了极限规格H400 mm× 200 mm×8 mm×13 mm的Q275D热轧H型钢.结果表明:试制产品的上屈服强度为360～368 MPa,抗拉强度为480～500 MPa,伸长率为32.5 ％～33.0％,平均冲击功为154～233 J,各项性能指标满足标准要求.
关键词:
热轧H型钢
,
再结晶控制轧制
,
Nb微合金化
鲁怀敏
,
汪开忠
,
吴胜付
,
黄贞益
钢铁钒钛
轧后经强冷的Q235H型钢铁素体晶粒大小和机械性能与轧后奥氏体晶粒大小和温降速度密切相关.以马钢现有轧后强冷系统为试验设备,以现有常规轧制工艺为条件,在水压和水流密度不变的前提下,通过改变冷却段的长度,即改变强冷时间,得到Q235H型钢不同温降速度、晶粒大小和机械强度及分布,同时验证了Hall-Petch公式的正确性,为制定合理的冷却工艺提供了依据.
关键词:
Q235
,
H型钢
,
快速冷却
,
铁素体晶粒
,
屈服强度
岳华
物理测试
针对生产中出现的Q390E热轧H型钢屈服强度不合格的原因进行了分析.通过工艺对比以及试样检测发现,轧制道次增加以及终轧温度过高会导致钢材晶粒较大,降低了钢材的强度.终冷温度过高导致位错、空位等缺陷在基体中保留较少,不利于组织细化,是导致屈服和抗拉强度强度不合格的主要原因.
关键词:
Q390E
,
H型钢
,
屈服强度
郭秀辉
,
杜传治
,
李超
钢铁研究
针对莱钢特厚规格Q275D热轧H型钢纵向低温冲击性能不合格的问题,采用金相显微镜和扫描电镜对其显微组织进行了分析,结果表明:混晶组织是造成低温冲击性能不合格的主要原因.根据莱钢现有设备,通过优化成分设计和控制轧制工艺参数,使得此规格H型钢晶粒尺寸细小均匀,-20 ℃纵向V型冲击功平均值大于160 J,满足相应标准要求.
关键词:
Q275D
,
V-Ti微合金化
,
再结晶控制轧制
,
特厚规格H型钢
谢应登
,
王仲琨
,
李蓓
物理测试
doi:10.3969/j.issn.1001-0777.2004.05.013
Q235B热轧H型钢拉伸试验后出现分层断口.用扫描电镜进行了显微观察,发现分层现象与试样中超长的带状组织密切相关.用能谱仪对断口分层处和超长铁素体带上的夹杂物进行了成分分析,证实都是硫化物.试样拉伸时在铁素体带上密集分布的硫化物处产生大量微裂纹,同时超长铁素体带的变形又受到阻碍,导致该处在试样拉断之前裂纹已经贯通,最终在断口上形成分层.因此,拉伸试验断口出现分层的原因是试样中存在密集分布的硫化物和超长的带状组织.
关键词:
H型钢
,
拉伸试验
,
分层断口
,
硫化物
,
带状组织
