Since the steel structure is often used in the manufacturing process, it is very important for the low-alloy high-strength steel for such applications to be welded by the arc welding process which is widely used in the thickness of the thin plate and the steel strip. It is also very important that the welds of the steel structures produced have the required strength and toughness. This will survive the most unfavorable conditions for the intended use. Recently, the development of low-alloy high-strength steel has been carried out simultaneously with the development of various welding processes, and special care must be taken to ensure that these steels have appropriate welding properties. Most of the low-alloy high-strength steels are well welded if the welding is done properly. For large sections and grades with higher carbon and manganese content, preheating and/or low hydrogen welding electrodes are required. For some low alloy high strength steels, low oxygen electrodes should be used regardless of their thickness. Gas-shielded molten-arc welding of low-alloy high-strength steels with a minimum yield point of up to about 345 MPa is generally suitable for low-carbon coated electrodes. For alloys with a minimum yield point above about 415 MPa and when special properties are required for the weld metal, such as higher corrosion resistance, low alloy steel electrodes are usually required. For submerged arc welding, gas shielded metal arc welding and flux cored arc welding, it is recommended to use the same metal-filled electrode as the recommended electrode for gas-shielded arc welding. For low-alloy high-strength steel sheets for the automotive industry, the carbon content is generally limited to not more than 0.13% for good spot welding performance.