原始组织对25MnV钢“零保温”淬火后组织性能的影响

采用正交组合回归设计试验方法,分别以淬火和热轧为预处理工艺,研究了不同原始组织条件下25MnV钢“零保温”淬火后的强度和硬度,并进行了组织分析.试验表明,经2次淬火,该钢得到极细的板条状马氏体组织,具有很高的强硬性,其性能优于热轧态“零保温”淬火.在较低温度“零保温”淬火时,原始组织对25MnV钢的强硬性影响显著,随淬火温度升高,其影响逐步减弱.通过低温“零保温”奥氏体逆相变淬火,可显著提高该钢的力学性能.     

热变形对冷轧工作辊用锻造高速钢CCT曲线的影响

以自行设计的冷轧工作辊用锻造高速钢为研究对象,采用膨胀仪测定了其静态CCT曲线,采用Gleeble-3500热模拟试验机测定了其高温形变后的CCT曲线（动态CCT曲线）。在金相显微镜下对不同冷速冷却后的显微组织进行了观察并测定了其维氏硬度,分析了热变形对连续冷却转变曲线的影响。结果表明：冷轧工作辊用锻造高速钢在快冷速下得到隐晶马氏体＋残奥＋碳化物,慢冷速下得到的是珠光体＋碳化物。冷速大于0．1℃／s时,均能得到马氏体组织,说明该钢具有良好的淬透性。热变形对珠光体临界转变速度影响不大,但却能减小珠光体转变的温度区间和马氏体转变开始点的温度范围。     

Effect of fast cooling rate on the microstructure and mechanical properties of low-carbon high-strength steel annealed in the intercritical region

The effect of fast cooling rate on the microstructure and mechanical properties of low-carbon high-strength steel annealed in the intercritical region was investigated using a Gleeble 1500 thermomechanical simulator and a continuous annealing thermomechanical simulator. The results showed that the microstructure consisted of ferrite and bainite as the main phases with a small amount of retained austenite and martensite islands at cooling rate of 5 and 50 ℃/s, respectively. Fast cooling after continuous annealing affected all constituents of the microstructure. The mechanical properties were improved considerably. Ultimate tensile strength(UTS) increased and total elongation(TEL) decreased with increasing cooling rate in all specimens. The specimen 1 at a cooling rate of 5 ℃/s exhibited the maximum TEL and UTS×TEL(20% and 27 200 MPa%, respectively) because of the competition between weakening by presence of the retained austenite plus the carbon indigence by carbide precipitation, and strengthening by martensitic islands and precipitation. The maximum UTS and YS(1 450 and 951 MPa, respectively) were obtained for specimen 2 at a cooling rate of 50 ℃/s. This is attributed to the effect of dispersion strengthening of fi ner martensite islands and the effect of precipitation strengthening of carbide precipitates.     

一种微合金化马氏体不锈钢的连续冷却转变研究

用膨胀法结合金相与硬度分析研究了一种新型水轮机叶片用V、N微合金化CrNiMo不锈钢的连续冷却转变行为,获得了该钢的连续冷却转变（CCT）曲线及不同冷却条件下的显微组织和硬度。结果表明,试验用钢的1、3、和温度分别为580℃、730℃、295℃和190℃,其贝氏体和铁素体分别在冷速小于0.5和0.2℃/s时出现,冷速在0.056~0.5℃/s之间时,硬度随着冷速的增大迅速增加,尔后随着冷速的增大,硬度缓慢升高。     

终轧温度及轧后冷却速度对Q460C钢组织和相变的影响

在Gleebl-1500热应力／应变模拟实验机上热压缩模拟Q460C含铌钢的轧制过程,并控制终轧温度和轧后冷却速度。通过观察金相组织和膨胀曲线研究控轧控冷对Q460C钢组织和相变的影响,分析了轧制过程中可能诱导其裂纹产生的原因。结果表明,Q460C钢组织分布不均、控轧控冷工艺不合理均可能造成其裂纹的产生,提高终轧温度可促进相变提前发生,而在较高终轧温度下,轧后冷却速度对Q460C钢组织变化的影响很小。     

Effect of deformation and cooling rate on the transformation behavior and microstructure of X70 steels

The effects of the deformation in the non-recrystallization region of austenite and the cooling rate on the transformation behavior and microstructure of low-carbon low-alloy steel for pipeline application were studied on the thermal-mechanical simulator Gleeble-1500. It was shown that an increase in deformation amount can greatly increase the nucleation site of ferrite when deformed in the non-recrystallization region of austenite, and an increase in nucleation ratio can greatly refine grains. When the cooling rate is accelerated, the driving force of nucleation is increased and the nucleation rate also improves. Ultra-refine grains can be obtained by controlled rolling. The high density of ferrite nucleus, which forms along the austenite grain boundary, twin interface, and deforma- tion band are introduced in the matrix of austenite by the control of hot rolling, after which the microstructure can be refined. It was found that the acicular ferrite has a very fine sub-structure, high dislocation density, and a thin slab with ultra-fine grains. Small M/A islands and cementite are precipitated on the matrix of the slabs by the analysis technique of TEM and SEM.     

管线钢控轧控冷组织与性能

研究超低碳管线钢控轧控冷显微组织及力学性能。对管线钢进行实验室控轧控冷,对轧后试样进行力学性能测试,用扫描电镜和透射电镜对显微组织进行观察。试验结果表明,采用制定的控轧控冷工艺轧制后的试验钢有较好的强度和优异的低温韧性。钢轧后显微组织主要由针状铁素体和粒贝组成;在铁素体板条的内部和品界处存在缠结、塞积、高密度的位错,显著提高了钢材的强韧性。     

热轧TRIP钢的组织与力学性能研究

采用热轧后控制冷却的工艺制备了TRIP钢，拉伸试验表明，试验钢的性能为：σb=605 MPa，σs=440 MPa，δ=28．4％；对试验钢的组织进行了研究，定量金相检测结果表明，试验钢中残余奥氏体含量为5．6％．     

变形工艺对CSP微合金高强度钢组织和性能的影响

在热模拟实验机上进行不同变形温度和冷却速度试验，研究低温区变形温度和冷却工艺对CSP生产线上微合金高强度钢的组织和性能的影响。试验结果表明，变形应在单相奥氏体区内完成，适当降低变形温度有利于得到细小均匀的贝氏体组织；冷却速度对贝氏体组织有明显影响，冷却速度越快，贝氏体组织越细小，强度越高。     

不锈钢板坯连铸凝固特性的研究

分析了 2种不锈钢凝固时的结晶特性 ,模拟计算了连铸过程中不同拉速和不同二冷配水下铸坯温度场的变化 ,并分析了铸坯温度场的变化与铸坯质量的关系 总结出提高铸坯质量的二冷配水原则 ,为制定不同拉速下的二冷配水制度提供了科学依据     

热轧条件下产生的15MnV 钢混晶

本文用定量金相的方法研究了钢坯加热温度和热轧工艺参数是如何影响奥氏体和铁素体混晶,以及奥氏体混晶在热轧期间的变化趋势,目的在于为制定控制轧制工艺提供参考依据。     

7．9Mn－1．4Si－0．07C钢高强韧机理研究

通过热轧、温轧、奥氏体化、两相区退火处理得到7．9Mn－1．4Si－0．07C钢板,该材料的拉伸强度及塑性随奥氏体化温度不同而具有显著差异．奥氏体化温度降低,室温下奥氏体含量升高,综合力学性能提高．当奥氏体化温度由900℃降低为800℃时,所得到钢板的奥氏体体积分数由15％增加到28％,拉伸强度由1150MPa提高到1340MPa,塑性由21％提高至27％．实验钢优异的力学性能源于其中大量的超细铁素体及奥氏体,细晶强化使其具有超高强度,铁素体基体及变形过程中奥氏体向马氏体相变提供了良好的塑性．基体组织中的位错强化,形变诱导马氏体转变的TRIP效应等是增强该钢板加工硬化能力的主要因素．     

Controlled rolling and cooling process for low carbon cold forging steel

Effect of controlled rolling and cooling process on the mechanical properties of low carbon cold forging steel was investigated for different processing parameters of a laboratory hot rolling mill. The results show that the specimens with fast cooling after hot rolling exhibit very good mechanical properties, and the improvement of the mechanical properties can be attributed mainly to the ferrite-grain refinement. The mechanical properties increase with decreasing final cooling temperature within the range from 670 °C to 570 °C due to the finer interlamellar spacing of pearlite colony. The specimen with fast cooling after low temperature rolling shows the highest values of the mechanical properties. The effect of the ferrite grain size on the mechanical properties was greater than that of pearlite morphology in the present study. The mechanical properties of specimens by controlled rolling and cooling process without thermal treatment were greatly superior to that of the same specimens by the conventional rolling, and their tensile strength reached 490 MPa grade even in the case of low temperature rolling without controlled rolling. It might be expected to realize the substitution medium-carbon by low-carbon for 490 MPa grade cold forging steel with controlled rolling and cooling process.     

Influence of hot rolling conditions on the mechanical properties of hot rolled TRIP steel

Influence of hot rolling conditions on the mechanical properties of hot rolled TRIP steel was investigated. Thermomechanical control processing （TMCP） was conducted by using a laboratory hot rolling mill, in which three different kinds of finish rolling temperatures were applied. The results show that polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes. The finer ferrite grain size is produced through the deformation induced transformation during deformation rather than after deformation, which affects the mechanical properties of hot rolled TRIP steel. Mechanical properties increase with decreasing finish rolling temperature due to the stabilization of retained austenite. Ultimate tensile strength （UTS）, total elongation （TEL） and the product of ultimate tensile strength and total elongation （UTS×TEL） reaches optimal values （791 MPa, 36% and 28 476 MPa%, respectively） when the specimen was hot rolled for 50% reduction at finish rolling temperature of 700 ℃.     

不锈钢X射线应力测量

分析了2类不锈钢X射线的衍射特性.为判断奥氏体不锈钢扫描过程中出现的2个衍射峰能否作为应力测试的基础,在改建的残余应力测量平台上,应用自编的测量控制软件,基于衍射全过程的实时监测与处理功能,采用等强梁标定方法,对奥氏体不锈钢0Cr18Ni9(原始材料)、1Cr18Ni9Ti(去应力退火)及马氏体不锈钢(A335P92)3种材料进行多次测定,逐级加载的同时,分别采用X射线系统及电测法进行检测,通过与理论值进行综合对比,得出不锈钢的衍射特性.结果表明:奥氏体与马氏体不锈钢反映了不同的衍射特性;虽然奥氏体不锈钢(220)晶面127°的Kα衍射峰非常明显,且半高宽与抛物线2种定峰方法的精确度较高,但准确度差,由此峰计算出的应力与材料真实应力无关;而(311)晶面149°的Kβ衍射峰虽然峰背比低、误差偏大,但经过应力常数修正后可作为应力测定依据;马氏体不锈钢表现出与α-Fe相近的衍射特性,其标定的应力常数与常规α-Fe的应力常数相差7.8%.     

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

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

Microstructural evolution and tensile properties of low-carbon steel with martensitic microstructure during warm deforming and annealing

For preparing large-scale nano-grained and ultrafine-grained steel sheets by warm rolling and annealing,the effects of de- forming temperature on both the flow stress and the microstructure evolution of 09MnNiD steel with lath martensitic microstructure were studied by warm-compression test and transmission electron microscopy(TEM)observation.Thereafter,the steel with the lath martensitic structure was multi-pass warm-rolled and then annealed.TEM results indicate that nano-grained and ultrafine-grained steel sheets are formed by warm rolling at 400℃and annealing at 400-600℃.In comparison with the as-warm-rolled specimen,the tensile strength at room temperature changes a little when the rolled samples are annealed below 450℃,and the tensile strength is greatly lowered as the annealing temperature increases to above 550℃.     

魏氏组织和氧化物对HRB335钢筋脆断的影响

通过对HR335钢发生脆断因素分析发现，魏氏组织和氧化物是导致HRB335钢筋发生脆断主要因素，魏氏体的形成倾向主要与钢的成分（碳及合金元素的含量）奥氏体晶粒度和轧制时的冷却速度密切有关。而氧化物大小和数量取决于钢的氧含量。     

控轧控冷和回火工艺对超低碳贝氏体钢组织和性能的影响

研究超低碳贝氏体钢的控轧控冷和回火工艺对其组织及力学性能的影响。结果表明,在试验工艺下试样组织均为粒状贝氏体,且在820℃终轧、440℃回火时获得了高强度低屈强比的超低碳贝氏体钢;控轧控冷工艺可以细化贝氏体铁素体和M-A岛、降低铁素体含碳量、控制组织中软硬相的比例,从而提高材料强度、降低其屈强比。回火温度升高使贝氏体铁素体粗化、含碳量和位错密度降低、M-A岛分解成细小的板条贝氏体,并析出富铜原子团,这是材料获得高强度、低屈强比的主导因素。     

Martensite transformation induced by deformation and its phase electrochemical behavior for stainless steels AISI 304 and 316L

The martensite transformation induced by tensile elongation and its effect on the behavior or phase electrochemistry of AISI 304 and 316L in 3.5% NaCl solution were studied.The results show that the content of α′-martensite in stainless steel 304 increases with the true strain,As α′-martensite content increased.freee corrosion potential and pitting potential of stainless steel 304 in 3.5% NaCl solution appeared the change trend of a minimum.It was also found that pitting nucleated preferentially at the phase interfaces between martensite and austenits,There exsted apparent differnece between electrochemical properties of austenite and of martensite for stainless steel 304 and 316L in 3.5% NaCl solution.