HRB600E动态再结晶临界条件及动力学模型的构建

利用Gleeble-3500热模拟实验系统对HRB600E高强抗震钢筋进行研究,考察了变形温度为850~1000℃、应变速率为0.01~10.00 s^(-1)、最大变形量为60%条件下的动态再结晶行为。通过双曲正弦形Arrhenius关系计算HRB600E高强抗震钢筋变形激活能为232 kJ/mol。根据加工硬化原理和Cingara-McQueen流变应力模型得出的数据可以看出两者在动态再结晶的起始临界应力和应变处表现出相当高的一致性,但Cingara-McQueen流变应力模型得到的临界应力值较高。引入Z参数求出临界应力应变与Z参数的关系式为ε_(c)=0.0016Z^(0.18),σ_(c)=1.16 Z^(0.166)。优化Avrami等学者提出的动态再结晶动力学模型,计算出不同条件下的动态再结晶分数,并对计算结果与实验值比较,发现二者具有显著的相关性。

HRB600E高强钢筋混凝土柱抗震性能及恢复力特性

为研究HRB600E高强钢筋混凝土柱抗震性能,对6根配置HRB600E高强钢筋与1根配置HRB400E普通钢筋的正方形截面混凝土柱进行低周往复荷载试验.研究轴压比、箍筋间距、纵筋强度和纵筋配筋率对高强钢筋混凝土柱抗震性能的影响,建立HRB600E高强钢筋混凝土柱恢复力模型.研究结果表明:配置HRB600E高强钢筋混凝土柱的滞回性能、变形能力与耗能能力良好;轴压比增大,试件延性降低,承载力与耗能能力提升;减小箍筋间距,试件变形能力与耗能能力增强;增大纵筋配筋率,试件承载力提升,耗能能力与延性降低;建立的HRB600E高强钢筋混凝土柱三线型恢复力模型与试验结果吻合较好,为工程结构弹塑性分析提供参考.

HRB600E高强抗震钢筋试制开发

为适应建筑用钢市场发展需求,采用铌钒复合微合金化工艺,对HRB600E高强抗震钢筋进行了试制,并用拉力试验机、材料试验机和金相显微镜,对试制钢筋的力学性能、疲劳性能、显微组织及夹杂物进行了检验分析。结果表明,试制钢筋具有良好的抗震性、时效性、焊接性能及疲劳性能,综合性能良好;钢筋显微组织为铁素体+珠光体(体积分数≥45%),晶粒度≥10级,晶粒均匀,夹杂物主要为A、C和D类夹杂物,均<1.5级,夹杂物数量少且尺寸较小,钢筋内部质量良好。

HRB600E高强抗震钢筋制备工艺及特点分析

地震是一种常见的自然灾害,目前人类还不能有效避免.地震的破坏性和危险性非常大,因此,为最大程度保障建筑内人员安全,在建筑建造过程中,必须要考虑到建筑的抗震性能.就建筑抗震来说,使用高强抗震钢筋是提升建筑物抗震能力的关键,同时高强钢筋的推广使用也是经济节约与绿色制造的需求.本文以HRB600E高强抗震钢筋为例,阐述了这类钢筋的特点及优势,分析其化学成分及力学性能要求,同时对HRB600E高强抗震钢筋的制备方案进行了研究,并在此基础上提出了提升高强抗震钢筋制备质量的对策.

HRB600E钢筋混凝土柱抗震性能及有限元分析

为研究配置HRB600E钢筋混凝土柱抗震性能,对不同轴压比和配箍率的5个试件进行低周反复加载试验,并通过ABAQUS软件进一步分析混凝土强度及配筋率对试件抗震性能的影响。研究结果表明:配置HRB600E钢筋的混凝土柱承载力高、变形及耗能性能良好;随轴压比增加,试件承载力、初始刚度增大,延性相对降低;随配箍率增大,试件延性和耗能能力增大。建立的ABAQUS有限元模型能较为合理准确的模拟出HRB600E钢筋混凝土柱的受力性能。随混凝土强度提高,各试件承载力相差不大,延性和耗能能力有所增强;随纵筋配筋率增加,试件承载力、延性和耗能能力增强。

Metallurgical Design, Development and Strengthening Mechanisms for HRB600E Reinforcing Bar

High-strength,anti-seismic requirements represent the development tendency to hot-rolled ribbed bar used for the reinforcement of concrete.In this paper,metallurgical design,development and strengthening mechanisms for 600 MPa reinforcing bar with anti-seismic requirements have been studied and presented based on the production practice of 335 MPa,400 MPa and 500 MPa grades.Through trial and error,it was found that alloy design with niobium plus vanadium is the best way to achieve the optimum combination of yield strength and anti-seismic properties,especially,small amount niobium addition can improve upon tensile-to-yield ratio.In order to clarify the underlying theoretical principles for the strengthening effects,qualitative and quantitative analysis for microstructure had been conducted with the aid of optical microscopy,scanning electron microscopy,transmission electron microscopy and chemical extraction technique,together with the solution and precipitation behavior of niobium and vanadium during the hot-rolling and cooling processes.Based on analysis results,it was found strengthening effects of both niobium and vanadium demonstrate some additional strengthening effects apart from predominated precipitation strengthening and grain refinement strengthening respectively.Although adding high vanadium contents is indispensable to achieve needed yield strength through precipitation strengthening effects,but fine VN particles precipitated in relatively high temperature also bring grain refinement effects for austenite and ferrite.Equally,grain refinement is not overall to describe the effects of niobium in long products,small amount of niobium contents is marked to improve upon tensile-to-yield ratio due to transformation strengthening resulted from the niobium contents in solution.Through the development of HRB600E,strengthening mechanisms of vanadium and niobium in medium carbon long products had been enriched.

高强度螺纹钢铸坯表面裂纹原因分析及控制

对采用转炉-精炼-连铸(全水型连铸机)工艺路线生产出的高强度螺纹HRB600(E)钢铸坯角部横裂纹进行了研究。结果表明:HRB600(E)铸坯角部横裂纹形成于结晶器。研究认为采用弱冷方式、控制浇铸速度、选用合理保护渣、合理二冷分配比等方式可有效解决铸坯角部横裂纹。工艺优化后铸坯角部横裂纹基本消除,且轧材无翘皮、结疤等质量缺陷。