Material and shape
Round steel: Round steel is a solid long steel strip with a circular cross section, usually made of carbon structural steel or alloy structural steel. Depending on the use, round steel can be divided into hot-rolled round steel, forged round steel and cold-drawn round steel. Its circular cross section allows round steel to have uniform force performance when subjected to loads such as pressure, bending and torsion.
Conventional steel: Conventional steel covers common types of steel, including but not limited to steel plates, steel sections (such as angle steel, channel steel, I-beam), steel pipes, etc. These steels have different shapes to meet different engineering needs. The materials of conventional steel are also diverse, ranging from low-carbon steel to high-strength steel, and even stainless steel, alloy steel, etc., to meet the strength and corrosion resistance requirements of various application scenarios.

Performance comparison
Round steel usually has high strength and toughness, and can withstand large loads and deformations. At the same time, round steel has excellent processing performance and is easy to cut, weld and forge.
Conventional steel exhibits different mechanical properties, corrosion resistance and welding properties depending on its specific type and material. For example, stainless conventional steel has excellent corrosion resistance and is suitable for harsh environments; high-strength conventional steel has higher yield strength and tensile strength and is suitable for structures that bear heavy loads.

Differences in production processes
Round steel is usually produced by hot rolling or forging. Hot-rolled round steel is made by heating the steel billet to a certain temperature and then rolling it multiple times on a rolling mill. Forged round steel is made by repeatedly hammering or extruding the steel billet through forging equipment to obtain the desired shape and properties.
The production process of conventional steel is more diverse, including hot rolling, cold rolling, extrusion, welding and other methods.

Galvanized wire is made of high-quality, low-carbon steel wire rods. It is made of high-quality low-carbon steel through drawing, pickling and rust removal, high-temperature annealing, hot-dip galvanizing, cooling and other processes. Galvanized wire is divided into hot-dip galvanized wire and cold-dip galvanized wire (electrogalvanized wire). The difference between them is: hot-dip galvanizing is diffusely plated in heated and molten zinc liquid, with fast production speed and thick but uneven coating. The color is darker, consumes more zinc metal, forms an infiltration layer with the base metal, has good corrosion resistance, and hot-dip galvanizing can be maintained for decades in outdoor environments.

Cold-dip galvanized wire (electro-beryllium zinc) is a wire that is gradually plated with zinc on the metal surface through the unidirectional current in the electric chain slot. The production speed is slow, the plating is uniform, the thickness is thin, usually only 3-15 microns, the appearance is bright, and the corrosion resistance is poor. Generally, it will rust in a few months. Compared with electrogalvanizing, hot-dip galvanizing has lower production costs and less impact on the environment than electroplating.

Cold-drawn wire: The raw material is wire rod, which is what we often call rebar. It is processed by the cold drawing process. In this process, the metal wire is stretched through a drawing die at room temperature, so that its size is reduced and its strength is increased. Cold drawing usually does not change the chemical composition of the metal. The surface of cold-drawn wire is relatively smooth, and there is no obvious oxide scale. At the same time, during the drawing process, a variety of surface treatments can be performed, such as polishing, wire drawing, copper plating, sandblasting, etc. Cold-drawn wire has high strength but low plasticity. It can be used as a material for drawing high-carbon steel wire, and can also be used to manufacture carbon structural steel with small and medium cross-section sizes, as well as building structural steel and rebars.

Galvanized wire: It is a process of coating a layer of zinc on the surface of the metal wire. It is usually carried out under the conditions of hot-dip galvanizing or electrogalvanizing. Galvanizing can prevent the metal wire from rusting and improve its corrosion resistance. There is a layer of zinc on the surface of the galvanized iron wire, which has a silver color. Galvanized wire has good toughness and elasticity, and has the characteristics of thick galvanized layer and strong corrosion resistance.

Hot cracks refer to the hot cracks generated when the weld and heat-affected zone metal cools to the high temperature range near the solidus during welding.

Cold cracks refer to the cold cracks generated when the weld joint cools to a lower temperature (i.e., below the temperature at which austenite begins to transform into martensite).

Reheat cracks refer to the cracks generated when the stainless steel plate is heated again within a certain temperature range after welding (stress relief heat treatment or other heating process) and then produced.

Stainless steel is a type of delayed crack steel. This type of steel has a lower thermal conductivity than ordinary carbon steel, a higher expansion coefficient, and slow heat conduction. It is easy to expand when heated and the expansion amplitude is large. Based on this property, many problems may occur in the welding process of stainless steel plates, such as undercut, pores, lack of fusion, cracks, etc.

Factors that cause cracking in stainless steel after welding include improper welding process, influence of material properties, improper preparation and handling, and stress changes during operation.

Stainless steel itself contains elements such as chromium and nickel, has excellent corrosion resistance and high temperature resistance, and is not easy to rust and deform during use. However, if the material quality is poor or impurities are mixed in, it will cause cracking during welding.

From the perspective of welding process, inappropriate welding parameters, uneven heating speed, and lack of proper cooling conditions may all lead to cracking. Stress caused by thermal expansion and contraction during stainless steel welding is also one of the main causes of cracking. The heat capacity and thermal conductivity of the material will also affect the stress of welding. If the temperature and stress distribution are not properly controlled during welding, welding cracking will occur.