论文部分内容阅读
In most engineering metallic structures,welded joints are often the locations for the crack initiation due to inherent metallurgical,geometrical defects as well as heterogeneity in mechanical properties and presence of residual stresses. In order to maintain structural integrity of welded structures for whole service life of the structure,relationship between welding process,properties(of base metal & weld joint) and performance of the structure(requirements & controlling factors of the service conditions) should be well-understood and established. The quality of the relationship between this 3P is crucial to obtain economic and safe design,fabrication and service life. Specific features of each welding and joining process should ideally be well understood by the designer for a selected material at the early stage of the design. Resulting micro-structural & mechanical and geometrical properties should be obtained to have defined or intended structural performance under either specific environment or stresses. Nowadays,use of advanced welding processes with high performance steels and aluminum alloys together with well established and high quality welding consumables ensures safe and economic design,fabrication,inspection and service of the welded components and structures. Additionally,new developments in the fitness-for-service(FFS) procedures(e. g. BS 7910,R6 and FITNET FFS) and codes have significantly increased the accuracy of the structural integrity assessment of weld flaws. More and more engineering structures are built using multi-material design approach where numbers of materials with significantly different mechanical properties are joined to create weight and cost-efficient structures. Structural safety evaluation of such material-mix structures require sound understanding and description of the welding process,interfacial & weld joint properties in conjunction with global behavior of the component under external loadings. The existing knowledge on the weld strength mismatch will significantly help to design innovative products and resolve complex deformation and fracture problems of such emerging structures. Such structures are expected to perform under severe service conditions with minimum maintenance and safely. This Houdremont Lecture will,therefore,address to the engineering significance of the relationship between different stages of the“life of the welded structure”which I have been describing as 3P(Process-Property-Performance) of welded structures.
In most engineering metallic structures, welded joints are often the locations for the crack initiation due to inherent metallurgical, geometrical defects as well as heterogeneity in mechanical properties and presence of residual stresses. In order to maintain structural integrity of welded structures for whole service life of the structure, relationship between welding process, properties (of base metal & weld joint) and performance of the structure (requirements & controlling factors of the service conditions) should be well-understood and established. The quality of the relationship between this 3P is crucial to obtain economic and safe design, fabrication and service life. Specific features of each welding and joining process should ideally be well understood by the designer for a selected material at the early stage of the design. Resulting micro-structural & mechanical and geometrical properties should be obtained to have defined or intended structural performance under either specific environment or stresses. Nowadays, use of advanced welding processes with high performance steels and aluminum alloys with well established and high quality welding consumables ensure safe and economic design, fabrication, inspection and service of the welded components and structures. the fitness-for-service (FFS) procedures (eg BS 7910, R6 and FITNET FFS) and codes have significantly increased the accuracy of the structural integrity assessment of weld flaws. More and more engineering structures are built using multi-material design approach where numbers of materials with significantly different mechanical properties are joined to create weight and cost-efficient structures. structural safety evaluation of such material-mix structures require sound understanding and description of the welding process, interfacial & weld joint properties in conjunction with global behavior of the component under external loadings. The existing knowledge on the wThis structure is expected to perform under severe service conditions with minimum maintenance and safely. This Houdremont Lecture will, therefore, address to the significance of the significance. eld strength mismatch will significantly help to design innovative products and resolve complex deformation and fracture problems of such emerging structures. of the relationship between different stages of the “life of the welded structure” which I have been describing as 3P (Process-Property-Performance) of welded structures.