微钛处理钢中的Ti/N比

采用焊接热模拟的方法,研究了Ti－N和Ti－Nb－N两种成份系列的微钛处理钢奥氏体晶粒长大的特点．试验结果表明,N含量为10×10－5时,加入适量的钛可以使微钛处理钢奥氏体晶粒粗化温度提高到1360℃以上．若钛含量相同或氮含量相同时,可用Ti／N比来比较细化奥氏体晶粒能力的大小,但Ti－Nb－N钢的理想化学配比值为2．74．     

微钛处理钢中的Ti／N比

采用焊接热模拟的方法,研究了Ｔｉ－Ｎ和Ｔｉ－Ｎｂ－Ｎ两种成份系列的微钛处理钢奥氏体晶粒长大的特点,试验结果表明,Ｎ含量为１０×１０＾－５时,加入适量的钛可以使微钛处理钢奥氏体晶粒粗化温度提高到１３６０℃以上,若钛含量相同或氮含量相同时,可用Ｔｉ／Ｎ比来比较细化奥氏体晶粒能力的大小,但Ｔｉ－Ｎｂ－Ｎ钢的理想化学配比值为２．７４。     

加热温度对HRB400钢奥氏体晶粒度的影响研究

介绍了铌微合金化处理工艺HRB400钢在不同的加热温度下对奥氏体晶粒度的影响。结果表明:在相同的加热温度下Nb含量高的奥氏体晶粒细,加入Nb合金有利于阻止加热时的奥氏体晶粒长大;Nb含量较高时轧制加热温度应略高于1150℃;Nb含量较低时轧制加热温度应略高于1050℃~1100℃。     

0.22C-0.45Mn钢低温奥氏体晶粒长大行为的研究

对0.22C-0.45Mn钢进行淬火工艺实验,研究加热温度、保温时间对奥氏体晶粒平均直径的影响,探究0.22C-0.45Mn钢在加热温度(870～990℃)和保温时间(15～120 min)范围内的低温奥氏体晶粒长大行为;基于Beck,Hillert和Sellars模型分别建立奥氏体晶粒平均直径的数学模型,预测0.22C-0.45Mn钢的奥氏体晶粒直径。结果表明：随加热温度的升高,0.22C-0.45Mn钢奥氏体晶粒直径近似呈指数形式增长,长大速率加快;随保温时间的延长,奥氏体晶粒增长速率减缓;3种晶粒模型中,Sellars模型的拟合精度最高,能较好地预测0.22C-0.45Mn钢奥氏体晶粒直径,可为实际生产中旋扩后的0.22C-0.45Mn钢低温热处理工艺提供参考依据。     

热轧螺纹钢筋连铸坯加热过程中奥氏体晶粒预测模型

利用有限元分析方法分析加热过程中螺纹钢连铸坯的温度分布随时间变化的规律。根据各节点温度与时间的关系,计算连铸坯各节点的加热速度,分析加热速度对奥氏体转变温度的影响规律。结果表明奥氏体化的温度与加热速度近似成线性关系。通过不同温度的中断淬火实验,研究奥氏体晶粒长大的动力学规律。结果表明,不同温度奥氏体晶粒长大激活能具有明显的差异。基于奥氏体晶粒长大和第二相粒子溶解之间的交互作用对不同温度奥氏体晶粒长大的动力学规律进行分析。     

稀土对高Nb钢奥氏体晶粒长大行为影响

钢中奥氏体晶粒越细小,经过组织转变后组织的力学性能越好.利用Gleeble-1500D热模拟机模拟稀土高Nb钢热处理过程,并对试样进行TEM观察与分析,研究稀土对加热时不同保温时间奥氏体晶粒大小的影响.结果表明:稀土能有效抑制加热过程中奥氏体晶粒长大,具有调整晶粒稳定性的作用,并且稀土降低沉淀相溶解的温度,促进第二相粒子在奥氏体中的溶解.     

结构钢奥氏体晶粒度的控制及检验方法的探讨

本文简介了航空结构钢奥氏体晶粒度的攻关成果,即提高奥氏体晶粒度粗化温度的重要途径是0.02～0.05％的残余铝含量和合理的热工艺。文中探讨了粗晶拉沿棒材外圆周规律性分布的成因(低温大变形和负偏析),粗晶的危害及改善措施,并对传统奥氏体本质晶粒度检验方法提出了更改意见。仅就晶粒度而言,最直接影响钢的机械性能的是实际晶粒度而不是本质晶位度,对于结构钢,应以实际晶粒度为验收标准。     

转炉22SiMn2TiB钢中奥氏体晶粒长大倾向的研究

对在不同热处理条件下，不同硼含量的２２ＳｉＭｎ２ＴｉＢ钢的奥氏体晶粒的长大倾向进行了研究。结果表明，当硼的质量分数为０．０００５％￣０．００３５％时，采用快速加热（到温装炉）的热处理制度，不不会造成该钢中奥氏体晶粒粗大，但如果在双相区内停留时间过长将导致粗晶并伴有严重的混晶现象。     

激光加热淬火时奥氏体晶粒超细化的研究

论述了回火马氏体的２０钢激光加热淬火后的组织及奥氏体晶粒变化的特征。结果表明：钢的非平衡组织经激光超高速加热淬火时，其奥氏体晶粒及淬火组织明显细化。同时，对激光超高速加热时奥氏体晶粒的超红化机理进行了初步的探讨。     

奥氏体晶粒尺寸对工艺参数的灵敏度方程及应用

为了便捷、准确地确定工艺参数对奥氏体晶粒尺寸的影响规律,考虑热加工工艺参数间的耦合关系,基于Hodgson再结晶模型建立奥氏体晶粒尺寸对工艺参数的灵敏度方程,探讨工艺参数对奥氏体晶粒尺寸的影响.研究表明:在单道次热加工过程中,变形速率、变形量、间隙时间、初始晶粒尺寸、间隙温度和变形温度灵敏度依次降低,工艺参数在不同的工艺过程中灵敏度不同;在多道次热加工过程中,工艺参数的灵敏度还与工艺参数所在道次和总道次数有关.H型钢开坯过程灵敏度分析结果表明,温度和后两个道次间隙时间是奥氏体晶粒尺寸的关键影响因素;降低温度并缩短间隙时间可以将H型钢开坯后的奥氏体晶粒尺寸减小26.2%.     

奥氏体状态控制及零保温加热工艺

根据加热奥氏体化的ＴＴＡ图与奥氏体晶粒、Ｍｓ、Ｈｖ的关系，通过作图法建立了连续加热奥氏体化及生产上实际的加热奥氏体化过程中奥氏体内碳浓度不均匀性及其变化规律图，认为最佳奥氏体状态是铁素体消失时的奥氏体，它可最有效的细化冷却后的组织。并根据国内热处理设备现状指出传统加热温度下零保温加热工艺的现实性、可行性。     

Effect of Continuous Cooling Conditions on Microstructure and Mechanical Properties of High Carbon Steel Rod

lintroductionElltectoidsteelhasafullypearliticmicrostructure.Fromdirectobservationandindirectdeductioninearlystage,theformingofpearliteterritoryisaprocessofaandFe,Cnucleationandgrowthalternately[1--2].SinceprioraustenitegrainsizeisoneofthefeatUrestha...     

Effect of austenitizing temperature on microstructure in 16Mn steel treated by cerium

The change of inclusions and microstructure of 16Mn steel treated by Ce were observed,and the effect of austenitizing temperature on the microstructure was also examined.The results show that the inclusions are transformed from Si-Mn-Al composite oxide and MnS into AlCeO3,Ce2O2S,and MnS composite inclusions after being treated by Ce.Plenty of intragranular ferrites are formed in 16Mn steel conraining ～0.017wt％ Ce.A large amount of intragranular acicular ferrites are formed after being austenitized for 20 min at 1473 K.The prior austenite grain size fit for the formation of intragranular acicular ferrites is about 120 μm.     

奥氏体不锈钢晶粒度对晶间腐蚀速度的影响

晶间腐蚀是诱导奥氏体不锈钢产生破坏的主要原因,而晶粒度对晶间腐蚀速度的影响不容忽视。通过在敏化温度和固溶处理温度对奥氏体不锈钢进行相应的热处理,利用草酸电解腐蚀法观察金相组织,并评定其晶粒度大小,通过极化曲线腐蚀实验,比较了奥氏体不锈钢晶粒度对晶间腐蚀速度地影响。实验结果表明奥氏体不锈钢在不同热处理条件下,其晶粒大小随保温时间延长而增大。随着奥氏体不锈钢组织的晶粒粗大,其晶粒度越小,奥氏体晶粒的晶间腐蚀的速度减慢。     

Roles of titanium-rich precipitates as inoculants during solidification in low carbon steel

The effect of titanium on the as-cast structure and the growth form of titanium precipitates, and the effect of cooling rate on the size and distribution of titanium precipitates were studied. It is shown that Ti-rich precipitates acting as heterogeneous nucleation sites play an important role in refining the grain size and increasing the equiaxed grain ratio. Cooling rate has a great effect on the size and distribution of precipitates. The number of precipitates increases and the size decreases with the increase of cooling rate. Ti-rich particles acting as het-erogeneous nucleation sites at the onset of solidification are observed in the experiment. This result suggests that TiN nucleated on Ti2O3 is an effective inoculant for δ-ferrite during solidification in low carbon steel.     

卷取温度对热轧TRIP钢残奥及力学性能的影响

为了研究卷取温度对热轧TRIP钢的残余奥氏体和力学性能的影响,使用金相显微镜、扫描电镜、x-射线衍射、拉伸实验等方法对三种卷取温度下制备的热轧TRIP钢进行分析.结果显示,随着卷取温度的降低,残余奥氏体晶粒尺寸变小,残奥体积分数和碳的质量分数也变小.450 ℃和400 ℃卷取温度下制备的热轧TRIP钢的残奥形貌的圆整性相差不大,而350 ℃卷取温度下制备的热轧TRIP钢的残奥形貌较圆整.热轧TRIP钢的力学性能随着卷取温度的降低表现为高的屈服强度和低伸长率,450 ℃卷取温度下制备的热轧TRIP钢的综合力学性能最优.     

钛微合金化高强度耐候钢成分设计及熔炼

在普通耐候钢Q450NQR1成分的基础上,通过理论计算,设计出一种钛含量为0.04%～0.10%、屈服强度为520～750 MPa的高强度耐候钢。按照成分设计要求,采用高频真空感应炉在1 873 K条件下熔炼钢样,并对不同钛加入量的钢样进行成分和组织结构分析。结果表明,熔炼的钢样中氧含量为（17～26）×10-6,氮含量为（12～66）×10-6,钛含量为0.006 1%～0.059 0%;钢样组织主要由铁素体和珠光体构成,随着钢中钛含量的增加,晶粒明显细化,钢组织渐趋均匀。SEM分析表明,钢中长方体的TiN夹杂,是以球形的Al2O3、MgO和钛氧化物夹杂为核心生长的,必要时在微合金化处理之前将钢中的氧含量降低到一定程度。     

Recrystallization of High Carbon Steel during High Strain Rate

The recrystallization of high carbon steel during high temperature and high speed rolling has been studied by analyzing the Stress-strain curves and the austenite grain size. Isothermal multi-pass hot compression at high strain rate was carried out by Gleeble-2000. The austenite grain size was measured by IBAS image analysis system. The results show that static recrystallization occurred at interpass time Under pre-finish rolling, and at the finish rolling stage, due to the brief interpass time, static recrystallization can not be found.     

Austenite formation during intercritical annealing in C-Mn cold-rolled dual phase steel

Two different kinds of experimental techniques were used to in-situ study the austenite formation during intercritical annealing in C-Mn dual phase steel. The microstructure evolution was observed by confocal laser scanning microscope, and the austenite isothermal and non-isothermal transformation kinetics were studied by dilatometry. The results indicate that banded structure is produced for the reason of composition segregation and the competition between recrystallization and phase transformation. Austenite prefers to nucleate not only at ferrite/ferrite grain boundaries, but also inside the grains of ferrite.Furthermore, the austenitizing process is accomplished mainly via migration of the existing austenite/ferrite interface rather than nucleation of new grains. The incubation process can be divided into two stages which are controlled by carbon and manganese diffusion, respectively. During the incubation process, the nucleation rate of austenite decreases, and austenite growth changes from two-dimensional to one-dimensional. The partitioning coefficient, defined as the ratio of manganese content in the austenite to that in the adjacent ferrite, increases with increasing soaking time.