钻孔直径对静态破碎剂致裂性能影响试验分析

进行岩石切割或开采时,静态破碎剂(简称SCA)致裂性能受多种因素的影响。为了研究钻孔直径对SCA致裂效果的影响,研究设计三种不同的SCA浆液水剂比;通过五种不同直径的高强度钢管来模拟不同的钻孔直径,测试了试件中SCA产生的膨胀压力。结果表明:1大直径的钻孔易发生喷孔现象,且首次喷孔时产生的膨胀压力最大;2当SCA浆液水剂比一定时,SCA产生的膨胀压力随着钻孔直径的增大而增大,但不同钻孔直径的钻孔达到最大膨胀压力所需时间基本相同。     

板料冲压模具扩孔和渐进成形扩孔的对比分析

分别采用传统的锥形凸模和渐进成形工艺对板料的扩孔特性进行试验,其中渐进成形扩孔的工具轨迹根据传统冲压的锥形凸模的形状设计.探讨了工具轨迹对渐进成形扩孔特性的影响.结果表明:与传统冲压扩孔件相比,渐进成形扩孔件的厚度最薄处位于孔口向外偏置一定距离的圆周上,而不在孔口边缘;渐进成形扩孔件的变形模式为剪切变形和弯曲变形综合作用,扩孔件沿直径的厚度分布与初始板厚不满足正弦定理;与传统的模具冲压扩孔相比,渐进成形的扩孔率提高了24.4%.     

TC2Mδ1.5钛板翻边成形极限及非轴对称畸变的研究

为研究各向异性对圆孔翻边成形的影响,用TC2Mδ1.5 mm钛合金圆板料在室温及600℃高温条件下分别进行了圆孔翻边试验.结果发现,除翻边底孔尺寸小于极限值时在唇口边缘发生破裂的正常失效方式之外,冷翻边制件卸载后发生了凸缘平面翘曲、翻边孔口部椭圆化、唇口边缘高度不一致、壁厚分布不均匀等非轴对称畸变现象.高温热翻边成形有效地提高了成形极限,并消除了凸缘平面翘曲和口部椭圆化,但口部高差以及壁厚不均等现象依然存在.本文在给出极限翻边系数结论的同时,对非轴对称畸变现象进行了定量描述、分析与解释.     

基于DBSCAN算法与GMM 理论的铝合金板孔边疲劳裂纹萌生监测

针对航空结构中多孔铝合金板在疲劳载荷作用下的孔边裂纹萌生监测问题,以光纤传感系统为基础结合小波分解、含噪声的密度空间聚类以及高斯混合模型,提出了一种孔边裂纹萌生监测方法。首先以光纤光栅传感系统采集循环加载条件下多孔铝合金板孔边裂纹萌生至结构断裂全程中孔边微应变并构建孔边微应变曲线。对孔边微应变曲线进行小波分解,得到微应变曲线的低频分量与高频分量,并以低频分量最小值及高频分量突变作为孔边裂纹萌生特征。在分析裂纹萌生时引入DBSCAN 算法与GMM 理论用于计算孔边裂纹萌生时的疲劳加载循环数并进行比较与分析得到多孔铝合金板孔边主裂纹的萌生位置以及孔边主裂纹裂纹萌生时的疲劳加载循环数。试验结果表明:此监测方法能够准确定位出孔边主裂纹的萌生位置,计算孔边主裂纹萌生时的疲劳加载循环数,且疲劳加载循环数计算误差在5%以内。在未来可应用于全机地面疲劳试验、结构健康监测等多种场景。     

硫含量对中碳非调质钢中硫化物及组织的影响

利用真空感应炉冶炼了不同硫含量的中碳非调质钢,研究了S含量对非调质钢中硫化物形态分布及显微组织的影响.结果表明：在0.025%~0.065%范围内,随S质量分数的增加,非调质钢中硫化物的数量增多,偏聚分布现象加重;晶内铁素体比例随之升高,组织得到细化.通过热力学计算及相图信息研究了硫化物的类型转变. S含量增加时第Ⅲ类MnS在凝固末期以离异共晶形式较早析出,剩余液相中的S在凝固结束时以共晶形式析出为第Ⅱ类MnS.单独MnS以及MnS- V( C, N)复合硫化物均可作为晶内铁素体的有效形核核心,促进铁素体的生成.     

均匀化退火和锻造对双相耐磨钢强韧性的影响

研究了一种低合金双相耐磨钢经均匀化退火和锻造处理后的微观组织和强韧性能.结果表明:经980℃均匀化退火4,8 h和1 150℃锻造处理后,实验钢显微组织主要为板条状马氏体、针状贝氏体及少量残余奥氏体,锻造处理后的晶粒度最小为7.0~7.5级,均匀化退火处理后的晶粒度最大为6.5~7.0级.均匀化退火的保温时间是影响双相耐磨钢力学性能的主要因素,实验钢保温4 h时的冲击韧性和延伸率值高于保温8 h的值.锻造比均匀化退火更适宜于提高低合金双相耐磨钢的强韧性,优化工艺为始锻温度1 150℃、终锻温度800℃、锻造比2.     

Metallographic etching and microstructure characterization of NiCrMoV rotor steels for nuclear power

The grain size of prior austenite has a distinct influence on the microstructure and final mechanical properties of steels. Thus, it is significant to clearly reveal the grain boundaries and therefore to precisely characterize the grain size of prior austenite. For NiCrMoV rotor steels quenched and tempered at high temperature, it is really difficult to display the grain boundaries of prior austenite clearly, which limits a further study on the correlation between the properties and the corresponding microstructure. In this paper, an effective etchant was put forward and further optimized. Experimental results indicated that this agent was effective to show the details of grain boundaries, which help analyze fatigue crack details along the propagation path. The optimized corrosion agent is successful to observe the microstructure characteristics and expected to help analyze the effect of microstructure for a further study on the mechanical properties of NiCrMoV rotor steels used in the field of nuclear power.     

Enhanced mechanical properties of AZ31 magnesium alloy sheets by continuous bending process after V-bending

The effects of V-bending process, continuous bending process and combination process on the microstructure and mechanical properties and formability of an AZ31 magnesium alloy sheet were investigated. The experimental results showed that no twins were found in the microstructure of all samples after processes due to the fine grain. The V-bending and continuous bending processes were proved to be an effective approach to modify the mechanical properties and formability. While the samples after the combination process exhibited better mechanical properties and formability than the single processed sample. The yield strength significantly decreased with the value of 100 MPa and the fracture elongation enhanced to 18.3% at room temperature. The Erichsen value was 5.0 mm which was significantly increased by 117% compared with as-received sample. The superior formability of combination processed samples was mainly attributed to the smaller r-value and n-value.     

退火温度对超纯Cr17铁素体不锈钢冷轧板成形性能的影响

对一种铌、钛双稳定化的超纯Cr17铁素体不锈钢的冷轧板进行不同温度的退火实验,探讨了对组织、织构及成形性能的影响.研究结果表明,退火温度是影响成形性能的关键因素.随着退火温度的升高,晶粒的平均尺寸逐渐增大,不均匀化程度逐渐加重.并且,γ纤维织构逐渐增强,α纤维织构逐渐减弱,使-r值逐渐增大,而Δr值变化不大.为了防止"橘皮"缺陷的产生,退火温度应低于1 000℃,平均晶粒尺寸应控制在40μm以下.在保证不产生"橘皮"缺陷的前提下,试验钢的冷轧板经975℃退火后具有最佳的成形性能:-r值高达1.92,Δr值仅为0.12.     

Production of 316L stainless steel implant materials by powder metallurgy and investigation of their wear properties

In this study,the mechanical and wear properties of AISI 316L stainless steel implant materials,produced by powder metallurgy(P/M),were investigated.AISI 316L stainless steel powder was cold-pressed with 800 MPa of pressure and then sintered at 1200,1250 and 1300°C for 30 min as three sample groups.The microstructure,and mechanical and wear properties of the resulting steels were investigated.Light optical and scanning electron microscopiese were used to characterize the microstructure of the steels.Room temperature mechanical properties of the steels were determined by hardness measurements and impact tests.Wear was determined using the pin-on-disc wear test,and the results were evaluated according to weight loss.The results indicate that the sintering temperature,time and atmosphere are important parameters that affect the porous ratio of materials produced by P/M.Sintering at high temperature can eliminate small pores and make the residual pores spherical.The wear tests showed that the wear of the AISI 316L stainless steel implants changed depending on the sintering temperature and load.Spherical pores in the samples increase the wear resistance.Moreover,decreasing the porosity ratio of these materials improves all of their mechanical properties.     

卷取温度对热轧F/B双相钢组织性能的影响

采用轧后空冷+超快速冷却工艺,研究卷取温度对热轧铁素体/贝氏体(F/B)双相钢组织性能的影响规律.结果表明:卷取温度由504℃降至250℃时,铁素体体积分数变化很小(857%～878%),铁素体晶粒尺寸变化也很小(36～37μm),组织中的硬相由以贝氏体为主转变为以马氏体为主;实验钢的抗拉强度由510MPa升至597MPa,屈服强度由475MPa降至389MPa,延伸率变化较小(322%～350%).另外,随着卷取温度的降低,铁素体与贝氏体或马氏体间的变形协调能力降低,使扩孔过程中微孔提前形核,同时加快了已有微孔的长大及合并过程,导致试样发生的塑性变形减小,扩孔性能降低,扩孔率由1014%降至524%.     

Ti对C-Mn-V非调质钢组织与性能的影响

研究了 Ti含量和锻造工艺对 C-Mn-V 非调质钢组织与性能的影响,并把实验钢的性能与调质中碳钢进行比较。分析了含Ti 钢的显微组织特点,讨论了钢的组织与性能之间的关系.结果表明:加入少量的 Ti可以改善钢的显微组织,提高韧性,但加入过量(>0.044％)反而会使韧性下降。钢的强化因素是以 70％—80％的珠光体为主。钢中 Ti的最佳含量为0.02％。此外还计算了各组织因素对强度的贡献。     

低碳贝氏体钢中的时效析出行为

测定了Cu-Nb-Cr-Mo系低碳贝氏体钢的时效硬度变化行为,在Gleeble-1500热模拟试验机上模拟了各钢种的蠕变行为,利用金相显微镜、TEM研究了不同钢种的微观组织与沉淀析出.结果表明,含铜钢在不同温度时效时会发生明显的时效硬化效应,在不同温度的蠕变曲线上会出现平台,平台现象是由于蠕变过程中出现了第二相析出,平台出现意味着开始了第二相析出,平台结束则析出过程结束.     

特低渗透砂岩油藏剩余油分布的主控因素及有利区块评价

根据特低渗透砂岩油藏储量动用不均衡的特点,提出了采用动态生产指标来对生产区块进行标定和分类,并通过动、静态相结合的方法分析特低渗透油藏剩余油的主要控制因素,在此基础上,再利用模糊数学评判的方法进行定量分析,指出有利的挖潜区块。对胜利油区五号桩油田桩74块特低渗透砂岩油藏的动、静态特征分析表明,该油藏沉积微相、微型构造及储层非均质性是特低渗透油藏剩余油分布的主要控制因素。其中,沉积微相的控制作用最强,微型构造次之,非均质性控制作用最弱。在沉积微相中,中扇亚相的辫状水道微相是最有利的微相带,中扇水道侧缘微相具有一定的可采储量,但由于相带狭窄不利于后期调整加密;朵叶体微相的井网稀,具有一定的生产开发潜力;顶凸底凸型和顶底均为鼻状凸起型微构造组合模式,水淹程度弱,既是高产区也是剩余油富集区。渗透率变异系数为0.3~0.9的区域,剩余油相对富集。最后以5砂组为例,采用模糊数学方法并结合剩余油控制因素分析结果进行了剩余油定量评判,指出了有利区域,经检验取得了良好的效果。     

Zr含量对微合金钢组织和性能的影响

研究了Zr含量对微合金钢组织和性能的影响。低碳含Zr钢的组织为铁素体 珠光体，随着Zr含量增加，钢中含Zr夹杂物的尺寸有所增大。微合金钢中添加的Zr，对钢的强度和塑性影响不大；Zr含量在0．01％-0．03％时，单位面积夹杂物颗粒数较少，微合金钢的低温韧性最好。     

管线钢硫化氢应力腐蚀的影响因素

为了解决国产高强钢的H2S应力腐蚀开裂(sulfide stress corrosion cracking，SSCC)敏感性问题，采用恒载荷拉伸法(constant load tensile)和慢应变速率法(slow strain rate test，SSRT)测试了在含H2S的介质中不同焊接匹配及不同冷变形度条件下管线钢母材及其焊接接头的SSCC性能。结果表明，不同的焊接匹配导致管线钢具有不同的耐腐蚀性能；冷变形促进了材料局部微观缺陷内能的增加，这些缺陷所在的位置往往是氢易被捕捉的地方；随着冷变形度的增加．材料的抗腐蚀能力降低，可见，焊接匹配和冷变形度是影响国产管线钢SSCC的重要因素。     

边水断块油藏蒸汽吞吐开发效果分析

边水小断块稠油藏蒸汽吞吐的效果受多因素的影响,产出水性质的识别对分析小断块边水活跃程度、储量动用状况等尤为重要.作者以新庄油田57 断块稠油开发为侧,在对注蒸汽吞吐开发过程中油层物理和流体变化规律分析的基础上提出了产边水识别的综合判断方法,用周期内生产井的综合含水变化特点、周期产水量/注蒸汽量比值,以及对比累积产水量与累积注蒸汽量等多参数综合分析,将生产井进行科学分类.在此基础上,进一步分别分析产边水井、正常生产井的开发特点及影响因素,提出了生产井到油水边界的合理距离和边部生产井的工作制度,从而避免生产井多周期低效生产,对提高该类油藏的开发效果有重要的意义.     

Influence of semisolid forging ratio on the microstructure and mechanical properties of Ti14 alloy

The present work is focused on the microstructure and mechanical properties of Ti14 alloy with different semisolid deformation ratios during forging tests. The results revealed that the forging ratio had a significant effect on the precipitation of the alloy. Fewer plate-shaped Ti₂Cu tended to precipitate on grain boundaries with higher forging ratios, and finally the plate-shaped Ti₂Cu formed precipitate-free zones along grain boundaries with a forging ratio of 75%. The precipitation on grain boundaries was found to be controlled by a peritectic reaction. Large forging ratios accelerated the extrusion of liquid and resulted in less liquid along the prior grain boundaries, which reduced the peritectic precipitation in this region and formed precipitate-free zones during re-solidification. In addition, increasing the forging ratio could accelerate dynamic recrystallization, which is favorable for improving the semisolid formability. The tensile ductility increased with increasing forging ratio, and a mixed fracture mode, involving both cleavage and dimple fracture, was observed after forging with a forging ratio of 75%, which is attributed to the presence of precipitate-free zones formed along grain boundaries during semisolid processing.     

正交各向异性单层板轴向拉伸时圆孔边应力集中的研究

本文对复合材料的孔边应力进行了理论计算与测试研究。文中引用了正交各向异性单向板圆孔边应力集中系数的理论计算式。介绍了用光弹贴片法对拉伸时圆孔边应刀集中系数的实测．测试值中考虑了贴片的增强效应与泊松比失配影响。最后对测试值与理论值进行了比较，符合较好。     

面向高性能结构材料的超细晶粒钢研究现状及发展方向

实现传统钢铁材料性能的全面升级符合社会可持续发展战略,组织超细化是同时提高钢铁材料强度和韧性的最佳强化机制。大量研究成果表明,通过不同的晶粒细化工艺可使钢铁材料组织细化到微米级、亚微米级和纳米级,使得传统钢铁材料的综合力学性能得到大幅度提高。但目前困扰超细晶粒钢的焊接技术尚未得到彻底解决。现阶段易于工业化晶粒超细化处理工艺所制备的超细晶粒钢,其焊接问题主要表现为焊接热影响区(HAZ)存在不同程度的脆化和局部软化现象,严重影响了焊接接头与母材性能的匹配。基于氧化物夹杂诱导形核的晶内针状铁素体组织强度高、韧性好,具有很强的自身细化能力,通过氧化物冶金技术获得具有大量有益微夹杂物的超细晶粒钢有望解决其焊接性问题。深入研究钢材基体中超细夹杂物形成与作用机理和焊接HAZ晶内针状铁素体的形成规律及影响因素,制备焊接性能良好的超细晶粒钢是新一代超级钢材料研究的重要发展方向。