High-strength steel with good weldability is delivered in the following conditions: normalized rolled (N), mechanically controlled rolled (M), and quenched and tempered (QT). Normalized steel was first developed in the 1940s, with a yield strength reaching 460 MPa. Quenched and tempered steel was first developed in the 1960s, with a maximum yield strength of 1300 MPa. Mechanically controlled rolled steel was developed from the 1970s, with a maximum yield strength of 960 MPa.

For applications where high strength and toughness requirements are not generally necessary, standard hot rolling or normalizing is sufficient to meet the required mechanical properties. Through these production processes and different alloy combinations, it is possible to produce steels with thinner thicknesses and strength grades lower than Q355 and Q420.

For steels requiring higher strength or lower-temperature toughness, a finer microstructure is needed. A production method combining thermomechanical rolling and water cooling is typically employed; steel produced using this method is also known as thermomechanically controlled rolled steel (TMCP steel). Furthermore, trace amounts of niobium (Nb) are often added during the production of high-strength steel to further refine the crystal grains, and vanadium (V) is added to increase strength. For steels of the same strength grade, thermomechanically rolled steel often has a lower carbon content, and the finer grains result in higher strength and toughness.

Quenched and tempered steel, primarily in plate form, is typically used in non-structural applications such as mining, where there is a greater demand for thick plates. The delivery condition of this steel is usually not mechanically rolled (M) or normalized (N). Because quenched and tempered steel (QT) has a higher carbon content and higher content of other alloying elements, control over welding is particularly important. Although the strength grade of quenched and tempered steel (QT) can be lower than Q460, it is generally used in structural applications only when the strength of mechanically rolled steel cannot meet the requirements, such as Q690 to Q960 grades.

Weathering steel possesses excellent resistance to atmospheric corrosion, and its strength can now reach the Q550 level. Welding techniques for weathering steel have also been developed. Weathering steel is now used in exposed structural components of bridges and buildings.

To meet the requirements for strength and toughness, all high-strength steels typically contain one or more microalloying elements, such as niobium (Nb), vanadium (V), or titanium (Ti). The content of these elements is extremely small, less than 0.01% (i.e., less than 1,000 g/ton). Each individual microalloying element has its specific metallurgical effect. For example, adding niobium can make the steel grains finer, which not only increases the yield strength but also improves its low-temperature toughness. Conversely, adding microalloying elements also further reduces the carbon content of the steel, thereby improving its weldability.

For quenched and tempered (QT) steel plates delivered in a quenched and tempered state, or when the steel strength requirement exceeds 500 MPa, molybdenum is typically added during the production process in addition to standard microalloying to meet additional performance requirements. This is because these high-strength steels have high requirements for strength, toughness, and wear resistance. The molybdenum content is generally controlled within the range of 0.1% to 0.7%, with the actual amount increasing as the product strength and plate thickness increase. Adding molybdenum also significantly improves the mechanical properties of the weld heat-affected zone, preventing excessive softening of the heat-affected zone.