Huamin LIU
材料科学技术（英文）
The closed-died cold forging technology of the bevel gears used in Jada car was investigated. With the analysis of the strain field and velocity field of the plastic deformation and the endured forces of the dies, the filling rules for the metal were analyzed by the elastic-plastic finite element method (FEM). The results show that there is a great difference among closed-die cold forging, extrusion and forging, as far as the metal flowing is concerned. The outer addendum cannot be filled completely in the closed-die cold forging of the bevel gears, and the round angle will be formed. But it does not influence the application of the bevel gears. At the beginning, the rigid area is formed in the cavity of the lower die. And then it will move upwards to supply the metal for the gear filling. For the closed-die cold forging of the bevel gears, the force acting on the upper die and the lower die is significantly different.
关键词:
Bevel gear
,
gear
,
closed-die
,
cold
,
gorging
,
FEM
,
f
C.H. Surberg
,
P. Stratton
金属学报(英文版)
Although cold treatments have been used to reduce the retained austenite in the cases of carburised steels for many years, there are little data on deep cold temperatures below -70oC or treatment times longer than an hour or two. This study set out to determine the effects of such deep cold treatments at temperatures down to -150oC for up to 24 hours. The study investigated the effects of deep cold on microstructure, hardness profile, residual stress and internal oxidation on two typical carburising steels, 16MnCr5 and 21NiCrMo2.
The study found that for both 16MnCr5 and 21NiCrMo2 carburised to a case depth of approximately 0.8mm, the longer and colder the deep cold treatment, the more of the austenite retained in the case was converted to martensite and the harder it became. After low temperature tempering the hardness difference was smaller, but still significant. In both steels the case appeared more refined and homogeneous after deep cold treatment. Deep cold treatment had a negligible effect on the core properties of either steel.
关键词:
Carburised steel
,
steel
,
Deep
,
cold
,
Retained
,
aus
郝建民
,
朱军
,
陈永楠
,
陈宏
,
丁业立
表面技术
doi:10.16490/j.cnki.issn.1001-3660.2017.03.023
目的 研究常压低温冷等离子体还原过程中气体常量对Fe2O3还原过程的影响.方法 采用冷压成形后高温烧结的方式制备Fe2O3试样块,利用射流型常压冷等离子体还原铁基氧化物,通过X射线衍射仪分析还原前后的物相,用扫描电镜观察还原前后的微观形貌,讨论了还原过程中气氛的作用和影响.结果 等离子体的还原能力取决于还原气体的成分与含量,其中氮等离子体在常温常压条件下无法还原Fe2O3,氨气+氮气混合气体为工作气体的常压低温冷等离子体能将Fe2O3还原成Fe3O4和金属Fe,还原能力随着氨气含量的增加而增强,还原速率随着氨气含量的增加而下降.氨气在等离子体中可产生多种还原性物质,如N2H4、H和H2*等,能将Fe2O3还原,且过程表现为过渡还原,即Fe2O3先被还原成Fe3O4,再被还原成金属Fe.结论 常压低温冷等离子体中的电子与热效应无法还原Fe2O3,添加氨气后的等离子体中产生了一系列的活性物质,才能还原金属Fe表面的氧化物.
关键词:
氨气
,
离子体
,
常压
,
低温
,
还原反应
,
氧化铁
,
活性物质
Z.L. Mi
,
D. Tang
金属学报(英文版)
he influence of cold rolling reduction on microstructure and mechanical properties of the TWIP (ttwinning induced plasticity) steel was investigated. The results indicated that the steel had better comprehensive mechanical properties when cold rolling reduction was about 65.0% and the annealing temperature was 1000℃. The tensile strength of the steel is about 640MPa and the yield strength is higher than 255MPa, while the elongation is above 82%. The microstructure is composed of austenitic matrix and annealing twins at room temperature, at the same time, a significant amount of annealing twins and stacking faults are observed by transmission electron microscopy (TEM). Mechanical twins play a dominant role during deformation, and result in excellent mechanical properties.
关键词:
cold rolling reduction
,
rolling
,
reduction
,
annealing
,
tempera
何岳
,
向嵩
,
石维
,
刘建敏
,
梁宇
,
陈朝轶
金属学报
doi:10.11900/0412.1961.2016.00186
通过OM, SEM, EBSD观察和EIS谱、动电位极化曲线测试等手段分析了不同应变下冷拔珠光体钢的腐蚀形貌、组织演变及点蚀在其演变组织中的分布和铁素体取向差分布, 研究了冷拔珠光体钢的横纵截面组织演变对其点蚀行为的影响. 结果表明, 由于横截面和纵截面组织演变规律的不同, 不同应变下冷拔珠光体钢的横截面和纵截面的耐蚀性分别表现出不同的变化规律: 随着应变的增加, 横截面耐蚀性持续下降, 而纵截面耐蚀性先降低后回升. 通过表征点蚀在冷拔演变组织中的分布规律, 发现珠光体组织的晶界、珠光体团界面、相界面对点蚀敏感性高, 是点蚀倾向于萌生和生长的区域, 冷拔变形造成界面面积增加, 使横截面和处于第一阶段应变ε ≤1.2的纵截面的耐蚀性显著下降. 铁素体<110>织构形成导致晶体取向差分布规律的改变会使纵截面在第二阶段ε =1.6的耐蚀性改善.
关键词:
冷拔珠光体钢,
,
点蚀,
,
组织演变,
,
电子背散射衍射(EBSD)
孙琳
,
林化强
,
林鹏
,
王兵
,
胡昌飞
材料开发与应用
针对高寒地区气候特征,将低温和高低温交变设为主要环境参数因素,对8种轨道车辆橡胶材料进行了试验室力学性能分析.通过高低温力学测试和交变温度试验,比对轨道车辆材料的力学特性.结果表明,几种橡胶材料的性能随高低温和交变温度呈现较大的差异性,这种差异性主要与橡胶的胶种和配方有关.低温力学性能和低温回弹测试结果表明,高柔顺性的橡胶材料(如顺丁和天然橡胶)具有良好的低温力学强度和弹性.交变温度试验结果显示,8种橡胶材料试验后拉伸强度多出现下降.
关键词:
轨道车辆
,
橡胶
,
高寒
,
力学性能
