Weldability
The weldability of steel refers to the ability to obtain a high-quality welded joint under specific welding process conditions. Weldability can be categorized into two aspects: weldability during the welding process and weldability regarding service performance. Weldability during the welding process refers to the susceptibility of the weld seam and the adjacent metal to forming hot cracks or cooling-induced shrinkage cracks. Good weldability means that neither the weld metal nor the adjacent base metal develops cracks under specific welding conditions. Weldability regarding service performance refers to the impact toughness of the weld seam and the ductility of the heat-affected zone (HAZ); the mechanical properties of the steel in the weld seam and the HAZ are required to be no lower than those of the base metal. my country employs testing methods for both process-related weldability and service-related weldability.
Durability
Many factors affect the durability of steel. First, steel has poor corrosion resistance, so protective measures must be taken to prevent corrosion and rusting. Protective measures include regular painting and maintenance, the use of galvanized steel, and-in environments with highly corrosive media such as acids, alkalis, or salts-specialized protective measures. For example, offshore platform structures utilize "anodic protection" to prevent jacket corrosion; by attaching zinc ingots to the jacket, the seawater electrolyte preferentially corrodes the zinc, thereby protecting the steel jacket structure. Second, because the failure strength of steel decreases significantly under high temperatures and long-term loading compared to its short-term strength, "endurance strength" (or creep-rupture strength) must be determined for steel subjected to prolonged high-temperature conditions. Steel also undergoes a phenomenon known as "aging," where it naturally becomes harder and more brittle over time. For steel subjected to low-temperature loading, impact toughness must be tested.
