合金化和球化工艺对超高碳钢组织和性能的影响

 研究了合金化和球化工艺对超高碳钢组织和性能的影响。用扫描电子显微镜、透射电子显微镜和能谱仪观察了钢的组织形貌和元素分布。结果表明：在碳和铬含量相同的超高碳钢中加入同量的合金元素铝和硅时,铝可明显抑制锻造组织中网状或粗大的颗粒状碳化物的析出、细化珠光体组织和控制石墨形成。UHCS 213Si和UHCS 261Al钢经850 ℃×3 h球化退火处理后,都能得到较好的球化组织,其力学性能分别为：UHCS 213Si钢,Rm=1 033 MPa,Re=734 MPa,A=149%;UHCS 261Al钢,Rm=973 MPa,Re=677 MPa,A=182%。     

Structural control of Fe-based alloys through diffusional solid/solid phase transformations in a high magnetic field

Abstract

A magnetic field has a remarkable influence on solid/solid phase transformations and it can be used to control the structure and function of materials during phase transformations. The effects of magnetic fields on diffusional solid/solid phase transformations, mainly from austenite to ferrite, in Fe-based alloys are reviewed. The effects of magnetic fields on the transformation temperature and phase diagram are explained thermodynamically, and the transformation behavior and transformed structures in magnetic fields are discussed.     

FES-DP系统及Z参数法评定Cr5Mo钢的剩余寿命

珠光体耐热钢是石化装置常用的炉管材料,针对其在高温服役中的安全评估问题,研究开发了FES-DP高温管线安全评估决策支持系统,并介绍了FES-DP系统的基本结构.针对常用的耐热钢Cr5Mo介绍了寿命评估的基本策略,提出用P=29.608-Z-5.0851gσ表征平行于Cr5Mo钢持久性能主曲线的曲线族,其中Z=0.203(E-1),参数Z表征了持久性能退化程度,E为球化等级.由此可以通过对构件组织的评定来定量预测构件的剩余寿命.     

亚共析钢复相组织中铁素体晶粒尺寸测定方法

亚共析钢复相组织主相的晶粒尺寸主要采用金相法和扫描电镜 EBSD 法。其中,金相法可以测量晶粒尺寸并对其评级,定量测量过程需要手动完成;扫描电镜 EBSD 法可对经过电解抛光的试样进行晶粒尺寸的自动测量,借助两相花样质量的差异,实现对铁素体+珠光体复相组织中铁素体晶粒的自动统计。     

珍珠岩制备不燃轻质保温材料

介绍用发泡珍珠岩生产不燃轻质保温板、耐高温板、珍珠岩硅藻土制品、珍珠岩砂浆、耐热混凝土及珍珠岩耐火材料的工艺和制品性能。     

铸件基体珠光体百分比含量磁性检测原理及干扰因素

根据磁化率与金属基体内珠光体含量的相关性，采用磁性法制作的仪器可迅速简便地检测铸件的珠光体含量，并且在严格控制生铁来源或及时重新标定的条件下，可满足工程精度的要求。     

Formation kinetics of austenite in pearlitic ductile iron

This work evaluated the isothermal transformation of austenite in unalloyed pearlitic ductile iron and drew the isothermal phase diagram of austenitization in the ductile iron. Austenite forms at grain boundaries and then grows up to graphite regions during austenitiza-tion. The formation kinetics of austenite complies with the Avrami equation, in which the parameter (n) ranges from 4.71 to 4.99. The start time and finish time of transformation can be calculated at each temperature using the Avrami equation.     

Back-scattered electron imaging combined with EBSD technique for characterization of pearlitic steels

Microstructure of pearlitic steels subjected different heat treatments were characterized combining the usage of back-scattered electron imaging and electron backscatter diffraction in a scanning electron microscope. The results indicated that the method used in current study enabled the acquisition of pearlite nodule, colony and interlamellar spacing of pearlite structure only through sample preparation of one time. Both the morphology of pearlite lamellae and the crystallographic orientation of ferrite matrix can be released in back-scattered electron imaging image and electron backscatter diffraction micrograph acquired at the same region. The definitions of pearlite colony and the low-angle boundaries existed in ferrite matrix were also discussed based on this method.     

H13钢锻后热处理工艺对碳化物形态及分布的影响

通过金相分析H13钢锻后热处理过程中的组织变化,发现:锻造、球化退火对改善碳化物尺寸、分布均匀性有一定作用;采用正火、球化退火可对奥氏体中析出的碳化物的形态、分布有改善,但组织中夹杂物、共晶碳化物制约着H13的性能;锻造后常规热处理工艺对共晶碳化物的分布及形态没有影响。     

马氏体切变学说的评价

到目前为止,材料学界普遍认为马氏体相变是切变过程,有人则认为切变机制是成熟的理论,其实不然．综合分析了1930年以来提出的所有切变机制,指出各切变机制均与实际不符合的缺点,尚未形成普遍成熟的理论,而是切变学说．将新发现的珠光体浮凸,结合贝氏体、马氏体表面浮凸现象,一并分析了浮凸的形成机制,认为形成表面浮凸的主要原因是各相比体积不同,相变时试样表面不均匀体积膨胀所致．表面浮凸是过冷奥氏体转变产物的普遍现象,因而指出马氏体的切变机制缺乏实验依据．马氏体相变中,原子是极为复杂的集体有组织的位移,不是简单的机械式的切变过程．