一种Ti-6Al-2Zr-1Mo-1V合金锻件的宏观与微观组织特征分析

研究了Ti-6Al-2Zr-1Mo-1V合金环锻件的宏观和微观组织，分析了锻件的变形和热处理工艺。对Ti-6Al-2Zr-1Mo-1V合金环锻件采用了β→α β温度区域的热变形工艺，即在卢区温度下开始变形，α β区温度下结束变形，锻件的退火温度略低于β相的临界分解温度了TK；采用β→α β温度区域热变形的锻件具有中等强度水平，良好的室温冲击性能和高温蠕变、持久性能；β→α β温度区域的变形工艺具有简化变形工序、降低变形抗力的优点，但变形时间的控制较难掌握，需一定的实践探索。     

2A70铝合金五级盘锻件侧面开裂原因

通过对2A70铝合金五级盘锻件宏观组织和显微组织的分析，研究了该锻件侧面开裂的原因，同时对该锻件的生产工艺进行了分析。提出了预防锻造裂纹的措施。     

钢构件磁粉探伤的聚磁成因分析

通过磁粉探伤、低倍检验、金相检验、电子探针等检验和分析方法,得出了由C38N2制成的某钢构件的聚磁成因,并从构件加工等角度,分析了该类裂纹的产生机理。     

Macrostructures and mechanical properties of ultrasonic-assisted friction stir welding joint of 2024-T3 aluminium alloy

In friction stir welding of aluminum alloys, tunnel defect may occur due to insufficient plastic material flow caused by lower heat input in the weld region. The inadequacy in heat input is due to improper selection of friction stir welding tool and process parameters. Ultimately, such defects degrade the properties of weld and may pose serious concerns towards the integrity and safety of the weld component. In order to improve the properties of weld joints, an ultrasonic-assisted friction stir welding device has been configured where ultrasonic energy is transferred from an ultrasonic unit directly into one of the workpieces near the tool. Using this configuration, ultrasonic-assisted friction stir welding was conducted on 6 mm thick 2024-T3 aluminum alloy sheets. The macrostructure and mechanical properties of these welds were compared with the welds of this alloy prepared by conventional friction stir welding using identical process parameters. The results show that the welding speed can be increased while satisfactory weld quality is still ensured. The ultrasonic energy transferred in this configuration could enlarge the volume of weld nugget zone. Also, the influence of ultrasonic energy on the suppression or elimination of the tunnel defect is quite apparent. However, any beneficial effects of ultrasonic vibration on the tensile strength and the elongation of the joint were less obvious in this configuration.     

低倍检验在铸坯质量控制中的应用

介绍了天铁炼钢厂铸坯低倍检验技术在质量控制中的应用情况,分析了低倍组织缺陷的产生原因。通过采用低倍检验技术对连铸工艺参数的确定、设备运行状况的判断及提高铸坯质量起到了很好的作用。     

EFFECT OF ROTATING MAGNETIC FIELD ON MACROSTRUCTURE OF A CENTRIFUGAL CASTING Al-1%Cu ALLOY

1. IntroductionCelltrifugal casting has been broadly used as it offers many advantages over the conventional casting methods. In a celltrifugal casting process, liquid metal is introduced intoa die that is spinning at a high rotational speed. The metal will take the shape of the dieand be subjected to a force 40 to 50 times of gravityg which then usually makes the castmore dense. The cast is also very clean, since the non-metallic inclusions that are presentin the liquid metal are celitrifuged…     

低压交流脉冲对A357合金凝固宏观组织的影响

针对A357铝合金,利用低压交流脉冲处理,研究了脉冲电流对该合金凝固宏观组织的影响.试验结果表明:低压交流脉冲可实现铸件晶粒整体细化,且细化晶粒的电流密度存在一个阈值和饱和值.在凝固过程的不同阶段施加脉冲电流,发现细化作用只发生在形核阶段.低压交流脉冲电流密度对晶粒密度的影响规律与过冷度的影响相一致,脉冲电流在形核阶段可提供一个附加能量,降低形核势垒,导致晶核增殖,晶粒组织细化.     

超高碳钢化学成分中铝含量的合理选择

借助相图计算及试验分析,对含碳1．5％(质量分数)的超高碳钢化学成分铝的合理选择进行了分析研究。结果表 明,随铝含量增加,A1温度升高,珠光体相变组织片层间距减小,网状碳化物减少。随铝含量增加单相奥氏体区变小变无, 液化温度降低,热加工性能恶化。综合考虑,含碳1．5％(质量分数)的超高碳钢化学成分铝的合理添加量应选择为2．0％(质 量分数)左右。     

高功率激光立体成形Ti-6Al-4V合金组织研究

针对高功率条件下激光立体成形Ti-6Al-4V合金组织特征展开研究,揭示高功率条件下组织形成机理,并对比分析了高功率与中/低功率条件下组织形成的差异及原因。结果表明:由于高功率条件下具有更低的温度梯度和更高的凝固速度,激光立体成形Ti-6Al-4V合金的宏观组织由粗大的柱状晶、竹节状的小柱状晶和等轴晶三部分组成,并且沉积层之间存在层带;而中/低功率条件下只有贯穿多个沉积层呈外延生长的粗大的柱状晶。高功率条件下层带内典型微观组织是由大量的魏氏α集束组成,而层带间为α板条编织成的网篮状组织,并且部分α相球化成等轴状。与中低功率条件下典型组织相比,高功率条件下α板条长宽比明显减小,不存在针状α。     

TiAl合金的热压缩模拟

在Gleeble1500热模拟实验机上对Ti-45Al-7Nb-0.15B-0.4W合金进行了恒应变速率热压缩实验。热模拟参数分别如下:温度为1050~1230℃,变形速率为0.01 s-1,变形量为30%。测试了不同温度下的位移-载荷曲线,观察了变形后的宏观与微观组织。结果表明:使用45#碳钢作为包套时,TiAl合金的包套热压缩温度不能低于1050℃,也不能超过1230℃,最优温度为1180℃;当包套TiAl合金的名义相对压缩量为30%时,TiAl合金块的实际最大相对压缩量为50%,TiAl合金和微观组织被拉长、压扁。