材料期刊网

Prediction of Carbon Concentration and Ferrite Volume Fraction of Hot-Rolled Steel Strip During Laminar Cooling

Y.T. Zhang , C.Z. Wang , D.Z. Li , Y.Y. Li

金属学报(英文版)

A phase transformation model was presented for predicting the phase fraction transformed and the carbon concentration in austenite for austenite to ferrite transformation during laminar cooling on run-out table in hot rolling strip mill. In this model, the parameter k in Avrami equation was developed for carbon steels. The wide range of chemical composition, the primary austenite grain size, and the retained strain were taken into account. It can be used to predict the ferrite volume fraction and the carbon concentration in austenite of hot-rolled steel strip during laminar cooling on run-out table. The coiling temperature controlling model was also presented to calculate the temperature of steel strip. The transformation kinetics of austenite to ferrite and the evolution of carbon concentration in austenite at different temperatures during cooling were investigated in the hot rolled Q235B strip for thickness of 9.35, 6.4, and 3.2mm. The ferrite volume fraction along the length of the strip was also calculated. The calculated ferrite volume fraction was compared with the log data from hot strip mill and the calculated results were in agreement with the experimental ones. The present study is a part of the prediction of the mechanical properties of hot-rolled steel strip, and it has already been used on-line and off-line in the hot strip mill.

关键词: carbon concentration , null , null

PREDICTION OF CARBON CONCENTRATION AND FERRITE VOLUME FRACTION OF HOT-ROLLED STEEL STRIP DURING LAMINAR COOLING

金属学报(英文版)

关键词:

高取向低粗糙度金刚石薄膜生长的研究

康强 , 杨瑞霞 , 石双振

表面技术 doi:10.16490/j.cnki.issn.1001-3660.2015.02.006

目的：研究热丝化学气相沉积( HFCVD)工艺对金刚石薄膜生长的影响，确定影响金刚石薄膜生长的因素。方法采用热丝CVD法，以丙酮为碳源，在不同晶面的Si衬底上沉积金刚石薄膜，通过金相显微镜、X射线衍射仪分析薄膜生长特性。结果不同沉积温度下生长的金刚石薄膜表面形貌差异很大。在高、低碳源浓度下分别获得了(400)和(111)晶面取向的金刚石薄膜。采用分步沉积法，改善了成膜的效率。结论气源浓度和生长温度是影响金刚石薄膜生长的重要因素，分步沉积法对于金刚石薄膜的生长有较大影响。

关键词: 金刚石薄膜 , 择优取向 , 碳源浓度 , 表面形貌

不锈钢低温气体渗碳的C浓度与扩散应力测量与计算

王艳飞 , 巩建鸣 , 荣冬松 , 高峰

金属学报 doi:10.3724/SP.J.1037.2013.00537

开展316L奥氏体不锈钢块状试样低温气体渗碳实验,测量渗碳层内沿深度方向的C浓度和应力的大小及分布;基于应力-扩散耦合作用理论,建立渗碳后渗碳层内的C浓度和应力分布的计算模型,利用该模型计算上述渗碳实验后试样沿深度方向的C浓度和应力分布,并将模型计算结果和实验结果进行比较.结果表明,低温气体渗碳后钢在表层产生一层含高C浓度的渗碳层,渗碳层内重现高的压应力,C浓度和压应力均在表面处最大,随着深度的增加而逐渐降低,压力和浓度的大小之间呈直线关系;考虑应力-扩散的耦合作用的扩散计算模型计算得到的C浓度分布和实验测量结果符合的较好,表明扩散引起的应力在低温气体渗碳的C扩散中扮演重要角色;扩散压应力的产生显著增加了C的表观扩散速度,在低温气体渗碳等类似的渗碳或氮的扩散机制研究中,需考虑扩散引起的扩散压应力与扩散之间的相互作用关系.

关键词: 低温气体渗碳 , 316L奥氏体不锈钢 , C浓度 , 扩散应力

23Si2MnCrNiMoV钢固体渗碳层的影响因素

邸全康 , 朱洪武 , 王福明 , 李长荣

材料热处理学报

研究了渗碳温度、渗碳时间、扩散时间、深冷处理参数对23Si2MnCrNiMoV钢渗碳层的碳浓度梯度、表层低硬度区深度、有效渗硬层深度(550 HV0.3)、碳扩散距离、微观组织形貌等影响,实验研究的渗碳温度区间为890 ～ 970℃,渗碳时间为4～10 h,扩散时间为0～4h.结果表明,较多的残留奥氏体存在是造成渗碳表层高C低硬度的主要原因,控制C浓度为0.72％～0.86％时,可获得最大硬度,若进一步增加C含量,会形成大量的残留奥氏体,反而降低渗透层的硬度;深冷处理对有效渗硬层深度几乎没有影响,但可使表层低硬度区域从距表面0.7 mm缩至0.3 mm.

关键词: 23Si2MnCrNiMoV钢 , 渗碳层 , 碳浓度 , 渗硬层 , 残留奥氏体