摘要：The effects of parallel and angular butt designs with different gap widths on the microstructure and mechanical properties of the resultant magnesium joints in gas tungsten arc welding were investigated. The experimental results displayed that the tensile strength of the joint made with angular butt joint and 0.3 ram-wide gap reached 266 MPa, the joint fractured through the heat-affected zone or base metal during tensile testing, and the microstructure examination showed that no macropore appeared in the fusion zone. However, macropores in diameter of larger than 200 micron occurred for other joint designs, the tensile strength of the resultant joints decreased, and the joints fractured through the fusion zone during tensile testing. The fracture surfaces were examined by scanning electron microscopy and the microhardness distribution in the joints was measured by using a Vickers microhardness tester.

摘要：以铝合金联装架为产品对象,进行了铝合金联装架焊接变形控制的研究。通过焊接组件配对优化、焊接变形预判、焊接工装优化设计、零件焊接余量预留、焊后热处理过程控制等方式,控制了联装架的焊接变形量和焊缝质量。最终,上架对角线长度之差和底架对角线长度之差均不超过3 mm,上架安装面的平面度和底架安装面的平面度均不超过1.3 mm,焊缝质量满足QJ 2698A—2011Ⅱ级标准要求。

摘要：通过介绍城市黑臭水体现状治理情况,分析黑臭水体产生机理及形成因素,从传统治理技术和生物生态技术方面阐述了城市黑臭水体的治理技术以及应用,重点研究了生物生态治理技术中的微生物强化技术、生物膜技术、植物净化技术和生态河岸技术的原理及优点,为城市黑臭水体治理提供理论分析和治理思路。