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A STUDY OF CARBIDE GROWTH IN MAR-M247 LC ALLOY BY DIRECTIONAL SOLIDIFICATION METHOD

J.H Lee , J. Chen , S.J. Choe , Y.T. Lee and H.M. Kim(High Temperature Materials Laboratory , Korea Institute of Machinery & Materials , 66 Sangnam Dong , Changwon , Kyungnam , 641010 , Korea Manuscript received 26 August 1996)

金属学报(英文版)

The carbide growth behavior of MAR-M247 LC alloy was investigated by directional solidification and quench method. The carbide volume fraction, trapping and growth behavior were correlated with the growth rate.It was found that the carbide volume fraction decreased at slower growth rate.This decreasing was caused by lower solidliquid interface trapping ability at slower growth rate.

关键词: :carbide , null , null , null

S355J2W耐候钢的耐腐蚀性能

鲁二敬 , 卢峰华 , 许鸿吉 , 谢明 , 钮旭晶

机械工程材料

通过周期浸润腐蚀试验,对比研究了S355.12W耐候钢和Q345R低合金钢在NariSOs溶液中的耐腐蚀性能,并用扫描电镜对腐蚀产物进行了观察和分析。结果表明:在相同试验条件下,S355J2W耐候钢的腐蚀速率低于Q345R钢的;S355J2W耐候钢会在表面形成黑褐色锈层,而Q345R钢表面形成橘红色易剥落的疏松锈层;S355J2W耐候钢腐蚀产物微观形貌为沿放射性方向生长的针状晶体,Q345R钢为颗粒状聚合物堆积而成,形状无规则,颗粒之间有较大的空隙。

关键词: S355J2W耐候钢 , 周期浸润腐蚀试验 , 耐腐蚀性能

S355J2钢板表面裂纹成因分析及控制

孙雪娇 , 高立福 , 刘金超 , 闵凡启 , 张婷

物理测试 doi:10.13228/j.boyuan.issn1001-0777.20150106

针对S355J2钢板表面出现裂纹缺陷的现象,采用金相显微镜、扫描电镜、能谱仪等检验手段分别从表面裂纹形貌、非金属夹杂物、组织分布等方面进行一系列分析.结果表明:裂纹起源于结晶器保护渣的卷入,并且在加热保温过程中裂纹两侧发生了脱碳以及内氧化.

关键词: S355J2钢 , 表面裂纹 , 脱碳层 , 内氧化

S355J2W+N钢激光-MAG复合焊与MAG焊对比

谷晓鹏 , 段珍珍 , 邓钢 , 谷晓燕

材料工程 doi:10.11868/j.issn.1001-4381.2015.02.004

利用激光-MAG复合焊和MAG焊进行了厚板S355J2W+N低碳钢的焊接实验,分析了两种焊接方法接头的微观组织和力学性能.结果表明:复合焊和MAG焊焊缝接头均由焊缝区、过热区、重结晶区和不完全重结晶区构成,复合焊接头截面呈“高脚杯”状特点,焊缝填充量和热影响区宽度较MAG焊明显减小.复合焊由于冷却速率快,过热区魏氏组织略有增多,硬度高于MAG焊,抗拉强度和弯曲性能与MAG焊相比,无显著差异,均能够满足生产标准的要求.

关键词: S355J2W+N , 激光 , MAG , 复合焊 , 接头组织 , 性能

S355J2钢板坯角部横裂纹成因及控制

赵文博 , 王明林 , 张慧 , 袁守谦

上海金属

针对S355J2钢连铸坯角部横裂纹,现场取样,利用扫描电镜、能谱仪等检测手段分别从裂纹形貌、夹杂物的组成及分布等方面进行分析;同时采用辐射温度计对连铸坯矫直段角部温度进行现场测量.结果表明,裂纹主要分为非封闭的主裂纹和许多细小的封闭裂纹,主裂纹内含有Al、Ca、Mg等氧化物夹杂,且裂纹已经被氧化;细小的封闭裂纹中有保护渣成分,说明钢液在凝固过程有保护渣卷入.夹杂物聚集导致连铸坯在矫直阶段因内弧受到拉应力作用而产生应力集中,成为横裂纹出现的内因.铸坯矫直段角部及其附近温度为850℃左右,处于第三脆性区,成为横裂纹产生的主要原因.优化保护渣制度和炼钢工艺可避免卷渣行为的发生;采用倒角结晶器可使角部温度避开第三脆性区.

关键词: S355J2钢 , 角部横裂纹 , 夹杂物 , 角部温度

S355J2薄规格钢板冲击性能不合格原因分析及改进

郭潇 , 王智聪 , 付中原

钢铁研究

针对河北普阳钢铁公司生产的6mm厚S355J2薄规格钢板出现-20℃冲击性能不合格的问题,采用金相分析等手段,对造成钢板冲击性能不合格的原因进行分析,指出混晶以及大颗粒TiN夹杂是导致钢板低温冲击性能不合格的直接原因.通过调整化学成分和轧制工艺、利用Nb微合金化提高再结晶温度、不添加Ti元素、减少轧制道次等技术措施,消除混晶和TiN夹杂,有效地改善了6mm厚S355J2钢板的低温冲击性能,提高了产品合格率.

关键词: 薄规格钢板 , 低温冲击性能 , 混晶 , TiN夹杂 , Nb

Bi2Sr2CaCu2O8单晶S-N转变的E-J特性

臧超飞 , 何豫生 , 沈庆飞 , 昌俊 , 李春光 , 张国华 , 罗胜 , 齐志 , 尹道乐 , 丁克俭

低温物理学报 doi:10.3969/j.issn.1000-3258.2001.04.008

我们应用脉冲电流的方法测量了Bi2Sr2CaCu2O8单晶在4特斯拉强场下的大电流时等温E-J特性.我们观察到在大电流时,样品电阻率ρ迅速增大,随着电流的继续上升,经过一段正曲率增长阶段,几乎达到饱和值,最后经过一段负曲率上升,达到正常态,显示出完整的S形.应用尹道乐等人的统一物质方程理论,给出了实验曲线较好的数值拟合.根据拟合结果,讨论了理论中各个参量的物理意义.

关键词:

S355J2G3低合金钢焊接接头的组织和力学性能

崔岩 , 鲁二敬 , 吴晓明 , 张艳辉 , 吴昊

机械工程材料

通过拉伸、冲击、弯曲、硬度和金相等试验对S355J2G3低合金钢MAG焊焊接接头的力学性能与显微组织进行了研究。结果表明:采用G383G3Sil焊丝对S355J2G3低合金钢进行焊接时,可获得拉伸、弯曲和冲击性能均良好的焊接接头;接头硬度的分布较均匀,最高不大于380HV;焊缝组织为沿柱状晶晶界析出的块状先共析铁素体,晶内为细小密集的针状铁素体和少量珠光体;热影响区组织主要为先共析铁素体、针状铁素体、珠光体和少量的粒状贝氏体;母材为均匀细小分布的铁素体和珠光体。

关键词: S355J2G3低合金钢 , 焊接接头 , 力学性能 , 显微组织

Magnetization, internal energy and specific heat in a three-sublattice ferrimagnet or ferromagnet with vertical bar J(ab)vertical bar=vertical bar J(bc)vertical bar not equal J(ca)

Journal of Physics-Condensed Matter

The temperature dependences of the magnetization, internal energy and specific heat in a three-sublattice ferrimagnet or ferromagnet with /J(ab)/ = /J(bc)/ not equal /J(ca)/ are calculated within the framework of the linear spin-wave approximation, by employing retarded Green's functions. For both the ferromagnet and the ferrimagnet, the internal energy and the specific heat decrease with increasing J ' /J and/or the value of the spins. For fixed values of S,, Sb, S, and J ' /J, the internal energy and the specific heat increase, whereas the sublattice magnetization decreases with increasing temperature theta. The three-sublattice ferrimagnet has some particular characteristics which are not shown by the systems with two sublattices. For ferrimagnets, the antiferromagnetism of the system becomes weaker with increasing J ' /J. The sublattice magnetization at low temperatures (also the magnetization M(0) at 0 K) of a ferrimagnet increases with increasing J ' /J for fixed values of S(a), S(b) and S(c). The effects of the spins S(a) (S,) and Sb On the magnetizations of other sublattices differ. The characteristics of the a-sublattice are the same as those of the c-sublattice, due to their similarity as well as the symmetry of the system. The behaviours of the b-sublattice are different from those of the a- and c-sublattices, due to the asymmetry of the three-sublattice system. The spin-value dependences of the spin deviation Deltam per spin land also the energy for the zero-point quantum fluctuation) of the system are different for different sublattices. These differences are ascribed to the asymmetry of the three-sublattice systems, which leads to the new intrinsic properties of the systems.

关键词: layered heisenberg ferrimagnets;spin-wave theory;elementary;excitations;superlattices;systems;magnetoresistance;antiferromagnet;interfaces

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