通冷却介质的埋管铸造中预埋管熔合状况的数值预测方法

提出了一种利用Anycasting软件进行充型模拟、利用Fluent软件进行凝固模拟的数值预测方法,数值计算了埋管铸造工艺预埋管外壁固定点在充型、凝固阶段的温度变化,并与试验测试值进行了对比,结果表明,采用不同软件得到的各阶段计算温度与试验测试温度吻合良好,数值计算结果可信。为了充分验证这种数值预测方法的可靠性,将试验浇注的铸件剖开,发现宏观上预埋管与浇注本体熔合良好,显微照片显示界面处除少量气孔外,熔合较为理想,因此这是一种有效的数值预测方法。

锅炉F-A异种钢接头早期失效统计分析及防控措施

应用于超(超)临界机组的电站锅炉受热面的铁素体钢-奥氏体钢(F-A)异种钢接头经常发生断裂,断裂形式以铁素体钢侧熔合线开裂为主。对江苏省内超(超)临界锅炉F-A异种钢接头失效情况及检验结果进行了统计分析,发现F-A异种钢接头倾向于在低等级材料、薄壁管、较大附加弯矩、复杂管屏、焊缝根部存在焊瘤等情况下发生失效;且接头失效由熔合界面的氧化、蠕变及疲劳3种机制所支配。并进一步针对影响接头失效的关键可控因素提出了防控措施。

Microstructure and mechanical properties of interface between laser cladded Hastelloy coating and steel substrate

In order to improve the corrosion resistance of carbon steel,Hastelloy coatings were prepared on E235steel substrate by ahigh power diode laser with laser scanning speeds of6and12mm/s,respectively.The interface between the coating and substratewas firstly exposed by dissolving off the substrate.Its microstructure,composition and mechanical properties were systemicallystudied.Special“edges”along the grain boundary were found at coating/substrate interface.These“edges”consisted of intergranularcorrosion area and real grain boundary.The interface of coating mainly displayed austenite structure ascribed to the rapidsolidification as well as the dilution of Ni during preparation.Additionally,Hastelloy coating and its interface prepared at the speedof12mm/s showed higher hardness than that prepared at the speed of6mm/s.Grain boundaries had higher friction coefficient thangrains at both coating/substrate interfaces.Moreover,the interface at higher laser scanning speed exhibited smaller grains,lowerdilution rates of Ni and Fe as well as a better tribological property.

基于小波分析的聚乙烯管道电熔接头冷焊缺陷识别

为了实现聚乙烯管道电熔接头冷焊缺陷的自动识别,将超声相控阵检测所得图像的像素灰度值按列水平相加求和并归一化,得到一组一维信号,并对该信号进行小波分析。通过分析信号高频分量的幅值特征确定熔合界面的位置,并以此为参考点确定冷焊特征线的位置。研究结果表明,该方法能够有效抑制图像中部分干扰信号的影响,同时比较完整地保留图像中熔合界面和冷焊特征线的位置信息,从而快速地确定熔合界面和冷焊特征线的位置。