welded

Welded refers to an object that has been joined by welding, a fabrication process that fuses materials, typically metals or thermoplastics, by heating them to their fusion temperature with or without the application of pressure and with or without added filler material. Welded joints are designed to become a single piece as the materials solidify.

The most common category is fusion welding, which uses heat from electric arcs (shielded metal arc welding, MIG/MAG and TIG) or gas flames to melt the base materials and any filler metal. Other methods include resistance welding (spot and seam welding), energy-beam welding (laser and electron beam), and solid-state techniques such as friction welding, diffusion bonding, and ultrasonic welding. Each method has different heat input, speed, equipment, and material compatibility.

Key considerations in welding include joint design, surface preparation, filler metal selection, shielding gas, and heat input. The process affects the heat-affected zone, which can change microstructure and mechanical properties. Excessive heat can cause distortion or cracking and may require post-weld treatments. Weld quality is assessed through visual inspection and nondestructive testing such as ultrasonic testing, radiography, or magnetic particle testing.

Applications span infrastructure, shipbuilding, pipelines, automotive, aerospace, and general fabrication. Welded construction is favored for its strength, potential for automation, and ability to join complex geometries and dissimilar materials in some cases. Safety concerns include exposure to ultraviolet and infrared radiation, fumes, and sparks, requiring proper ventilation and protective equipment. Standards from organizations such as AWS and ISO govern welding procedures and qualifications.