GM模型的几何性质及统计检验

以空间向量几何理论为基础，详细地分析了Ｇａｕｓｓ－Ｍａｒｋｏｖ线性模型的几何性质；在实现了模型图形化描述的基础上，利用各解向量的几何及统计性质构造出了不同情形下的统计检验方法和相应的检验统计量，为全面、深入地研究和灵活运用该模型提出了一种简洁直观的数学方法     

扫描速度对硼铸铁气缸套表面钨极氩弧硬化效果的影响

研究了钨极氩弧扫描速度对硼铸铁表面硬化效果的影响规律。结果表明：扫描速度增加,硬化层宽度、深度减小,而硬度提高,裂纹率增大；硬化层硬度沿层深的分布是从表及里由高而低,在过渡区下降缓慢；沿层宽的分布是层中心最高,向两侧逐渐降低,直至硼铸铁基体达到最低值；在保证不出现裂纹的条件下,硬化层表面的最高硬度值可达61．4HRC,硬化层最高显微硬度值可达1156．4HV0．1；硼铸铁材料采用氩弧热源淬火时,淬硬层与基体之间过渡区明显,硬化区组织为莱氏体,过渡区为马氏体、残余奥氏体和少量石墨。     

THERMODYNAMICS ON THE SELECTIVE OXIDATION OF ELEMENTS IN MOLTEN MATTE AND METALS

总结讨论了熔锍及熔融金属中元素选择性氧化的行为,举出镍锍中 Ni 与 S,铁液中 Cr,V,Nb,Mn 或 P 与 C 作为应用的实例.利用热力学分析提出氧化的转化温度的概念,并指出二步及一步计算该温度的方法.在排除新相生成的晶核能的条件下,氧化的转化温度与氧的存在形式(无论是气态 O_2,溶于金属液中的[O]或炉渣中的 FeO)以及氧的压力或活度无关,而只决定于参加反应的物质及产物的本质及活度(压力).同时,转化温度不是一成不变的温度,而是随着熔池组成的改变而不断地在变化.降低气体氧化产物的分压将有助于降低氧化的转化温度.理论计算的转化温度可提供使熔池中一个元素的优先氧化而使另一元素保留不变的最佳条件.小型实验和工业上实践证明,转化温度的概念可以成功地控制吹炼操作,作到按意图进行选择性氧化.影响熔池内元素氧化顺序的动力学因素也作了简略的分析.对镍锍脱 S、不锈钢脱 C 以及高碳锰铁降 C 的吹炼,熔池温度永远要高于相应熔池组成的转化温度.而对铁水脱 Cr 和铁水提 V 或 Nb,熔池温度则应保持低于相应熔池组成的转化温度.P,C 在铁水中的氧化顺序,除与转化温度有关外,还取决于熔渣组成以及 CO 承担的压力.     

晶闸管式等离子弧切割机的使用与维修

本文介绍了晶闸管式等离子弧切割机的操作原理、使用和维修技术。     

Zr对Cu—Zn—Al形状记忆合金相变的影响

采用示差扫描热分析(DSC)、X射线衍射及透射电镜,研究了Zr对Cu-Zn-Al合金高温相变、马氏体正逆转变以及形状记忆效应的影响。结果表明,添加Zr0.35wt-％时,能有效地抑制α,γ相析出,促进β_2→DO_3→18RM转变。(M_s-M_f)及(A_s-A_f)温度区间较窄,马氏体相变激活能最低,马氏体变体间界面的可动性好,形状记忆效应最佳。     

Effect of heat treatment on the microstructure and hardness of C-Cr-W-Mo-V-RE Fe-based hardfacing layer

0IntroductionHot-rollers and scissors are the critical parts of thesteel rolling equipments.At present,the surface soften-ing,the early wearing and the tearing are the primary rea-sons for the lowservice life of the hot-rollers and scissors.Although hardfacing has been applied to repaire the partseasily being worn and torn,such as the hot-rollers and thescissors,and has been obtained economic benefits[1-3],this technology has common problem:if the hardfacing lay-er contains more excessive allo…     

EFFECT OF COMPOSITION ON HYDROGEN EMBRITTLEMENT IN Ni-Fe FCC ALLOYS

The ductility loss and threshold stress intensity,K_(IH)during hydrogen charging were measuredfor pure Ni and four Ni-Fe fcc alloys.The results show that ductility loss in 40Ni60Fe alloyand K_(IH)a 50Ni50Fe alloy have a minimum value.The variations of the amounts of hydride,hydrogen evolution and dislocation structure with composition have been investigated.The va-riation of hydrogen embrittlement susceptibility with composition measured by ductility lossand by K_(IH)or K_(IH)/K_C can be explained by means of the synthetical effects of amount ofhydride,solutionized hydrogen and the extent of dislocation planarity on hydrogenembrittlement susceptibility.     

EFFECT OF ALLOY ELEMENTS ON QUASIEQUILIBRIUM MICROSTRUCTURE IN Fe-Mn-Ni-Cr STEELS

The microstructures of Fe-Mn-Ni-Cr steels with medium carbon and the effect of alloy ele-ments on them have been investigated by means of X-ray diffraction quantitative phase ana-lyses,metallography and hardness tests.The volume fraction of martensite in steels quenchedat 1100℃ can be expressed as:f_M~(1100)=162.643-15.482Mn-7.36Ni-4.286(Cr+Mo+V)Based on this expression,the quasi-equilibrium microstructure diagram has been obtained.Itis shown that the effect of Mn on the austenite stability is greater than that of Ni.The equiva-lent [Ni]=2.104Mn+Ni and equivalent [Cr]=Cr+Mo+V.The driving force for martensite transformation at M_s point has been calculated to hedrastically decreased by element Mn.     

QUASI-EQUILIBRIUM MICROSTRUCTURES AND EFFECT OF ALLOY ELEMENTS IN Fe-Mn-Ni-Cr STEELS

本文利用X射线定量相分析及金相观察和硬度测试,考察了中碳Fe-Mn-Ni-Cr钢的组织及合金元素的作用。建立了经1100℃淬火后的马氏体体积分数与合金成分的定量关系式; f_M~(1100)=162.643-15.482Mn-7.36Ni-4.286(Cr+Mo+V)并在此基础上给出了亚平衡组织图。结果表明,Mn稳定奥氏体的作用大于Ni的作用。Ni和Cr当量分别以[Ni]=2.104Mn+Ni,[Cr]=Cr+Mo+V表示。计算了M_S点处的马氏体相变驱动力,指出Mn具有强烈降低相变驱动力的作用。     

共晶自生复合材料的晶形转变

自生复合材料的晶形转变受到成分过冷与曲面过冷两个因素的控制.非金属相具有较大的熔化熵且易形成小平面是改变领先相的因素,而领先相的改变则可能是晶形转变的根本原因.