316LN钢高温塑性及其断口特征

利用Gleeble-1500D热力模拟试验机,对316LN钢进行温度为950~1200℃,应变速率分别为0.005、0.05、0.5和1s-1的热力模拟试验。借助扫描电镜(SEM)对断口进行观察,研究316LN钢的高温塑性及高温断裂机制。结果表明:316LN钢高温断裂为韧性断裂,随着温度和应变速率的增加,韧窝尺寸增大,深度增加,塑性增加。同时,采用回归方法构建了断裂应变、塑性指标(延伸率和断面收缩率)分别与变形条件(温度和应变速率)的关系模型,应用这些模型可以计算一定条件下316LN钢的断裂应变、延伸率和断面收缩率,对制定316LN钢的锻造工艺有一定的指导作用。     

应力状态对316LN钢高温塑性的影响

对316LN钢在Gleeble-1500D热模拟实验机上做高温拉伸实验,试样尺寸为Ø/10.0 mm×121.5 mm,缺口半径分别为0.5、1.0、2.0、4.0 mm和∞(光滑试样),温度为950℃~1200℃,应变速率为0.5 s^-1,得到不同变形条件下试样的断面收缩率变化规律;通过数值模拟,得到开始拉伸时不同缺口拉伸试样最小横截面部位的应力三轴度分布.对比实验与数值模拟结果表明:316LN钢的高温塑性与应力三轴度和晶粒尺寸有关.如果晶粒尺寸相差不明显,应力三轴度起主导作用,应力三轴度越小,断面收缩率越大,塑性越好;如果晶粒尺寸相差明显,晶粒尺寸起主导作用,应力三轴度越小,断面收缩率越小,塑性越差.     

微合金化钢的动态再结晶及其显微组织的研究

应用Ｇｌｅｅｂｌｅ－１５００热模拟试验机测定了微合金化钢在不同终轧温度下的真应力－－真应变曲线，研究了终轧温度及微合金元素含量对动态再结晶的影响，研究结果表明，Ｖ，Ｎｂ可显著抑制微合金化钢轧制过程中形变奥氏体的动态再结晶，因此，在较高的终轧温度下，仍能得到细小而均匀的显微组织。     

轧制工艺对钒铌微合金化钢显微组织的影响

应用Gleeble—1500热模拟试验机对V、Nb复合微合金化钢进行了模拟轧制,测定了形变奥氏体的动态再结晶曲线,研究了轧制工艺对铁素体晶粒大小和亚结构的影响,从而确定了能够获得细小铁素体—珠光体组织的V、Nb含量及与之相应的轧制工艺。     

14SiMn3型贝氏体高强钢的复微合金化研究

结合国内资源优势,研究了用少量Ｍｏ、微量Ｖ、Ｂ、Ｒｅ进行复微合金化,对１４ＳｉＭｎ３型贝氏体高强钢的力学性能影响。结果表明：复微合金化可显著提高其空冷状态的韧性,明显改善低温韧性,并可显著提高回火抗力和高温回火后的强度。     

热老化对核级316LN锻造控氮奥氏体不锈钢微观组织及性能的影响

研究了热老化对核级316LN锻造奥氏体不锈钢的位错组态、电阻率及显微硬度的影响规律。结果表明,随着热老化的进行,奥氏体基体中位错密度总体下降,而始于晶界向晶内延伸的扩展位错数量增多且宽度变窄,其中,固溶态的扩展位错宽度约为1．0μm,热老化5000h后约为0．2μm。分析认为,碳原子在晶界及其附近微区的偏聚是引起位错亚结构变化的主要原因：电阻率随热老化时间的延长、检测温度的升高而增大,且热老化5000h后电阻率随温度的增长速率高于固溶态;晶内和晶界处的显微硬度值随热老化的进行均有所升高,二者之间显微硬度的差值逐渐增加。     

Nb微合金化钢异型坯连铸工艺的优化

为了减少Nb微合金化钢连铸异型坯表面裂纹缺陷，研究了Nb微合金化钢的高温塑性，并结合工业性试验，对Nb微合金化钢异型坯连铸二冷工艺制度进行了优化；另外对结晶器用保护渣的理化性能进行了改进，大大提高了Nb微合金化钢连铸异型坯表面质量。     

316LN热变形行为及动态再结晶晶粒的演变规律

采用热压缩试验研究了316LN不锈钢在温度1250℃-900℃,应变速率0．005s^-1～0．5s^-1,变形程度50％条件下的变形行为和组织演变;分析了变形参数对应力-应变曲线的影响规律,计算获得了该钢热变形应力指数和激活能;并通过动态再结晶晶粒演变规律的研究,建立了该钢热变形动态再结晶图,以及动态再结晶晶粒演变规律模型。研究结果可为316LN不锈钢锻造过程晶粒细匀化的控制提供科学的依据。     

Fe-3%Si电工钢的相图计算及组织分析

使用热力学软件分析了碳含量对Fe-3%Si的电工钢相图的影响,考察了奥氏体和铁素体两相区内两相相对量随温度的变化.结合金相法观察了不同加热温度及不同保温时间的淬火组织,初步确定了不同温度及不同保温时间下电工钢组织的形貌特征.     

Phase diagram structure model of glass

Phase diagram structure model of glass has been proposed and discussed. Validity of this model has been supported by lots of experimental data in various glass systems.     

Gelcasting of 316L stainless steel

A novel near-net process, gelcasting, was successfully used to prepare larger size 316L stainless steel parts with complex shape. In this study, the effects of process parameters on the viscosity of the slurry and the dry green strength were investigated. The results show that gas atomization (GA) powder is more suitable for gelcasting compared with water atomization (WA) powder. The maximum solid loading is 55vol% for ball-milled slurry with GA powders. And the optimum amounts of monomers (acrylamide (AM) methylenebisacrylamide (MBAM); the mass ratio, 30:1) and initiator in the AM system are 1.8% (based on the weight of metal powder) and 0.8%-1.4% (based on the weight of monomers), respectively, at which, the maximum green strength obtained is 33.7 MPa. The mechanical properties of the sintered specimen are as follows: ultimate tensile strength, 493 MPa; yield strength, 162 MPa; and HRB, 72.     

Gelcasting of 316L stainless steel

A novel near-net process, gelcasting, was successfully used to prepare larger size 316L stainless steel parts with complex shape. In this study, the effects of process parameters on the viscosity of the slurry and the dry green strength were investigated. The results show that gas atomization (GA) powder is more suitable for gelcasting compared with water atomization (WA) powder. The maximum solid loading is 55vol% for ball-milled slurry with GA powders. And the optimum amounts of monomers (acrylamide (AM) methylenebisacrylamide (MBAM); the mass ratio, 30:1) and initiator in the AM system are 1.8% (based on the weight of metal powder) and 0.8%-1.4% (based on the weight of monomers), respectively, at which, the maximum green strength obtained is 33.7 MPa. The mechanical properties of the sintered specimen are as follows: ultimate tensile strength, 493 MPa; yield strength, 162 MPa; and HRB, 72.     

EuCl3-PrCl3二元系相图的研究

利用DTA测定了EuCl3-PrCl3二元系相图,发现该体系有一个异份熔化化合物EuCl3·2PrCl3,转熔点为573 ℃,EuCl358.8%(摩尔分数);低共熔点为510 ℃,EuCl375.6%(摩尔分数).同时探讨了相图的某些规律.     

Biocompatibility of MIM 316L stainless steel

To evaluate the biocompatibility of MIM 316L stainless steel, the percentage of S-period cells were detected by flow cytometry after L929 incubated with extraction of MIM 316L stainless steel, using titanium implant materials of clinical application as the contrast. Both materials were implanted in animal and the histopathological evaluations were carried out. The statistical analyses show that there are no significant differences between two groups (P>0.05), which demonstrates that MIM 316L stainless steel has a good biocompatibility. Foundation item: Project (2003AA302210) supported by the National Hi-tech Research Program of China