H.B. Wu
,
H.T. Jiang
,
S.W. Yang
,
D. Tang
,
X.L. He
,
null
金属学报(英文版)
Cooled in water after isothermal relaxation of deformed austenite for different times, an Nb-bearing microalloyed steel always exhibits synthetic microstructures, in which bainitic ferrite dominates. Dislocation configurations and distributions of strain induced precipitates inside bainitic ferrite of samples relaxed for different times were distinct. When compared with the austenite model steel, which maintained fcc structure even at room temperature, the strain induced precipitates were not found in the sample without relaxation whereas these were distributed outside dislocations in sample relaxed for 1000s. Most of the strain induced precipitates distribute along dislocations and pin dislocations in sample relaxed for appropriate time. After bainitic transformation, the dislocations formed in deformed austenite remain to be pinned by the precipitates. When these samples were reheated to and held at 650 or 700¡æ, the non-equilibrious microstructures tended to evolve into equilibrious ones. The sample relaxed for 60s displayed the highest thermo-stability, whereas microstructure evolution was the quickest in the sample relaxed for 1000s even though it was the softest prior to reheating. Dislocations inside laths got rid of pinning of precipitates, and their polygonization became the precursor to the evolution of microstructures during reheated and held, followed by gradual disappearance of lath boundaries caused by dislocation climbing. Finally, recrystallization occurred and polygonal ferrite appeared. By hardness measurement, it was found that softening is not a single process occurring during reheated, in which hardness fluctuates with time. There were two peaks in the hardness-time curve of each sample having undergone relaxation, while single peak occured in the curve of the sample not being relaxed. These results indicated that the thermo-stability of microstructures was determined by their history of formation to a considerable degree.
关键词:
bainite
,
null
,
null
,
null
井敏
,
谭婷婷
,
王成国
,
冯志海
,
杨云华
,
潘月秀
材料科学与工艺
doi:10.11951/j.issn.1005-0299.20150208
东丽T800H和T800S是分别采用湿纺和干湿纺制备的两种力学性能相近的碳纤维，为弄清不同纺丝方法对T800级碳纤维微观结构的影响，采用扫描电镜、X射线衍射仪、小角X射线散射仪和高分辨透射电镜对这两种碳纤维进行测试，比较其表面形貌、断口形状和形貌、石墨微晶结构和微孔结构等．研究结果表明，湿纺制备的T800H比干喷湿纺制备的T800S的表面粗糙、断口圆度差、原纤尺寸较大、石墨微晶致密度差且发育不完善、内部微孔尺寸大、石墨微晶条带韧性差，这正是T800H的拉伸强度和断裂伸长率不如T800S的重要微观结构因素，但T800H的石墨微晶取向度不如T800S，孔隙率略高于T800S．
关键词:
碳纤维
,
微观结构
,
力学性能
,
表面形貌
,
孔结构
,
石墨微晶
王迎芬
,
彭公秋
,
李国丽
,
谢富原
,
刘勇
材料科学与工艺
doi:10.11951/j.issn.1005-0299.20150420
为了研究T800H碳纤维的表面特性及其与BA9918树脂的界面匹配性，分别采用SEM、AFM、XPS和TGA对T800H碳纤维表面形貌、表面化学特性以及碳纤维上浆剂热稳定性进行表征，测试了T800H／BA9918复合材料湿热处理前后0°压缩强度、90°拉伸强度和层间剪切强度，并得到了其在湿热处理前后的开孔压缩和冲击后压缩性能。测试发现T800H碳纤维表面有明显的沟槽，有利于表面机械啮合作用；T800H／BA9918复合材料经29 J能量冲击后压缩强度为314 MPa；在130℃湿态环境下其0°压缩强度和层间剪切强度保持率高于58％，开孔压缩强度保持率高于60％。试验结果证明T800H碳纤维与BA9918树脂具有良好的界面匹配性，T800H／BA9918复合材料具有优异的耐湿热性能。
关键词:
T800H碳纤维
,
复合材料
,
力学性能
,
湿热处理
李新梅
,
张忠文
,
邹勇
,
杜宝帅
,
邹增大
材料导报
根据新型耐热钢T92和Super304H钢的焊接特点制定了适宜的焊接工艺,研究了焊制的T92/Super304H异种钢焊接接头的力学性能.结果表明,T92/Super304H异种钢接头的各项力学性均能满足使用要求.焊缝金属的韧性远低于T92钢侧热影响区,焊缝金属的结晶形态对焊缝韧性有很大的影响.焊接接头中焊缝金属的硬度值最高,而T92钢侧热影响区硬度最低,并且不同热影响区部位显微硬度变化较大,Super304H钢侧热影响区硬度变化不大.
关键词:
T92钢
,
Super304H钢
,
新型耐热钢
,
异种钢
,
焊接接头
Huijie LIU
材料科学技术（英）
The friction stir weldabilities of the strain-hardened AA1050-H24 and precipitate-hardened AA6061-T6 aluminum alloys were examined to reveal the effects of material properties on the friction stir welding behavior. The experimental results are obtlained. (1) For AA1050-H24, the weld can possess smoother surface ripples; there is no elliptical weld nugget in the weld; there is no discernible interface between the stir zone and the thermomechanically affected zone; and the internal defect of the weld looks like a long crack and is located in the lower part of the weld. (2) For AA6061-T6, the weld usually possesses slightly rougher surface ripples; an elliptical weld nugget clearly exists in the weld; there are discernible interfaces among the weld nugget, thermomechanically affected zone and heat affected zone; and the internal defect of the weld is similar to that of the AA1050-H24 weld. (3) The effective range of welding parameters for AA1050-H24 is narrow, while the one for AA6061-T6 is very wide. (4) The maximum tensile strength efficiency of the AA1050-H24 joints is similar to that of the AA6061-T6 joints, i.e. 79% and 77%, respectively.
关键词:
Friction stir weldability
,
null
,
null
,
null
李朝阳
,
马贵阳
,
朱本光
,
乔伟彪
,
杜明俊
腐蚀与防护
在原油管输过程中，液相介质内常含有一定量以H2S为主的酸性气体，这些气体具有极强的腐蚀性，常引发管道内壁不均匀腐蚀或点蚀，从而发生泄漏事故。通过对T形管内气液两相流的研究发现，两相介质在分支处的分布总是不均匀的。利用CFD软件对T型管道内原油与H2S气液两相流动进行了数值模拟，得到了稳定状态下管道中H2S的分布规律。结果表明，原油流经T型管道时，会在支管口背流处生成稳定H2S高浓度区；原油流速越大硫化氢浓度变化越大；速度的变化对硫化氢高浓度分布区的范围影响不大。为管道腐蚀防护、确保管道安全稳定运行提供了理论依据。
关键词:
T型管道
,
硫化氢
,
数值计算
叶飞
,
张文征
,
张驰
,
齐彦
,
方鸿生
金属学报
doi:10.3321/j.issn:0412-1961.2000.07.001
介绍了获得满足△9平行法则的位向关系、惯习面、正空间和倒空间准不变应变线的计算方法,解释了高锰钢中先共析魏氏组织渗碳体在奥氏体晶内析出时的Pitsch和T-H位向关系.计算得到的位向关系和惯习面结果与实验结果吻合得很好.根据计算结果,将惯习面分解成原子级的台阶,绘制了Pitsch和T-H位向关系惯习面上的晶格匹配示意图.
关键词:
△9平行法则
,
相变
,
晶体学
,
界面
,
结构模型
