铁素体—珠光体型非调质钢及其控锻控冷技术

综述了国内外铁素体－珠光体型非调质钢发展现状，探讨了锻造温度、锻造变形量、变形速率及锻后冷却速度对非调质钢强韧化的影响，指出了旨在控制先共析铁素体组织参数和沉淀硬化效应的控锻控冷新技术。为稳定锻造用铁素体－珠光体型非调质钢性能，推动其规模化生产应用，开拓了前景。     

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 中厚板拉伸试样出现了延伸率不合问题，并且拉伸试样断口出现了层状撕裂现象。通过对试样断口形貌、试样变形区和未变形区金相组织的研究，认为：中厚板中心区域珠光体比例高是层状撕裂试样厚度中心呈现脆性的原因，这种脆性区导致在拉伸过程中最先萌生裂纹，并最终导致拉伸试样延伸率不合；出现层状撕裂的试样在拉伸之前并不存在结构上的分层和断口分层，在断口上出现的平行于轧制方向的裂纹是在拉伸过程中形成的；当珠光体带的宽度超过25 μm时，试样在拉伸过程中在珠光体带中易出现裂纹并导致断口出现层状撕裂。     

含硅过共析钢晶界铁素体形成的热力学分析

将合金元素在珠光体相变时无分配状态下形成的含Ｓｉ合金渗碳体做为一种介稳相处理，利用规则溶液亚点阵模型和有关文献中的数据，计算了含Ｓｉ合金渗碳体相对于无Ｓｉ渗碳体的自由能增量δＧＦｅ３ＣＳｉ，得到了渗碳体中含Ｓｉ量和δＧＦｅ３ＣＳｉ的对应关系；并利用Ｓｉ在不同温度下的分配系数，计算了Ｓｉ对ＦｅＣ合金介稳态γ／［γ＋Ｆｅ３Ｃ］相界碳浓度（Ａ′ｃｍ）的影响。所得结果认为，含Ｓｉ过共析钢珠光体转变时在原奥氏体晶界出现连续网状铁素体，是Ｓｉ增加含Ｓｉ渗碳体自由能，从而提高了介稳态γ／［γ＋Ｆｅ３Ｃ］相界碳浓度（Ａ′ｃｍ）的结果。     

强磁场对硅锰铸钢于A_1点附近等温珠光体相变的影响

通过开展12 T强磁下硅锰铸钢(50Si_2Mn_3)于A_1点温度附近不同等温时间的热处理试验,并对比强磁场与无磁场条件下等温珠光体相变试验结果,研究了磁场对珠光体转变量及组织形貌的影响。研究表明,对于50Si_2Mn_3在A1点以下较高温度范围内,强磁场可缩短珠光体相变的孕育期,促进硅锰铸钢珠光体转变,使其转变量明显增加;强磁场能够提高珠光体转变临界点,使50Si_2Mn_3在A1点以上等温过程中能够发生珠光体相变。     

原奥氏体晶粒尺寸对珠光体钢组织及韧性的影响

探索了奥氏体晶粒尺寸对珠光体等温转变组织特征以及对韧性性能的影响规律。研究表明,在相同等温转变温度下,珠光体片层间距无明显变化,随奥氏体晶粒尺寸的增加,先共析铁素体量减少而珠光体团尺寸增加。珠光体断裂韧性受控于裂纹前沿塑性影响区尺寸(1~2)δc,其中δc为临界裂纹张开位移,当原奥氏体晶粒大于(1~2)δc时,裂纹扩展阻力主要来自穿越珠光体片层α、θ相的颈缩、破断。当原奥氏体晶粒尺寸接近或小于(1~2)δc时,裂纹主要沿晶界、珠光体团界、α+θ片层界面扩展,通过扩展路径发生多次弯折消耗能量,随原奥氏体晶粒尺寸增加,准静态断裂韧度J变化幅度较小。而冲击韧性缺口前沿塑性影响区远大于原奥氏体晶粒,大角度晶界将促使裂纹的转折而提高扩展阻力,提高裂纹前沿塑性区大角度晶界密度有利于提高冲击功,冲击韧性Ak随晶粒尺寸的增加显著下降。     

真空珠光砂隔热性能的理论和实验研究

实验测定了不同粒径珠光砂在不同真空度下的表观导热系数。采用真空粉末材料的导热－辐射复合传热模型，给出数值求解结果。提出了利用此模型将实验条件下的数据外推到其他条件下的方法。     

45钢的球化规律探讨

研究了45钢的退火保温时间对球化结果影响。结果表明：在实验室条件下，45钢在740℃保温2个小时左右、670℃保温7h以上或仅在670℃保温22h以上，能得到较好的球化效果。     

Assuring Microstructural Homegeniety in Dual Phase and Trip Steels

The presence of ferrite/pearlite bands in dual phase and TRIP assisted steels is a consequence of microchemical segregation which causes mechanical properties anisotropy. Such inhomogeneous phase distribution produces a lowering of the mechanical properties such as fracture behaviour. This anisotropy is commonly not accounted in micromechanics computations which often assume a random distribution of phases in the solid. The present paper deals with an integral model for this undesirable band formation accounting for the solute segregation caused by solidification, microcomponent diffusion present in the austenitisation process, and the nucleation of the transformed phase in segregated regions. In the present work, the model was applied to two industrial grade dual phase steels and two TRIP assisted steels. The influence of such parameters on band formation is summarised in a number of “band prevention plots”, which are aimed at providing the optimum processing conditions for ferrite/pearlite band prevention.     

KB憎水膨珠保温砂浆及其应用

KB憎水膨珠保温砂浆由水泥、KB憎水膨珠、SF憎水粉及少量胶粘剂按一定比例干混而成,保温、防水、防火、容重轻,且集保温与找坡为一体,便于施工。本文结合工程实例说明了该砂浆在平面、立面以及节点处的施工方法。     

The analysis for morphological evolution and crystallography of degenerate pearlite in 100Mn13 steel

During approximate 773 K aging treatment of 100Mn13 steel, degenerate pearlite will occur and evolve into lamellar pearlite during growth process. The microstructures of degenerate pearlite and its evolutionary lamellar pearlite are observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that after 748 K, 773 K and 798 K aging, degenerate pearlites occur at grain boundary. At growth front of degenerate pearlite forming at 773 K and 798 K, pearlite presents a morphology of short lamellae of carbide and ferrite, indicating a trend of developing into lamellar pearlite. The higher the temperature is, the more obvious the trend is, and even a conventional lamellar pearlite has developed. However, there is no morphological evolution for degenerate pearlite forming at 748 K aging. Besides, the constituents of degenerate pearlite is identified as M₂₃C₆ and ferrite, and Kurdjumov-Sachs orientation relationship exists between them, (01 )_α//( 1 )_M23C6, [111]_α//[110]_M23C6. This orientation relationship maintains in morphological evolution from degenerate pearlite to lamellar pearlite.