Welding and deformation prevention of stainless steel grating

With the continuous development of petroleum, chemical, pharmaceutical and other industries, the demand for corrosion-resistant equipment is increasing. More stainless steel gratings are widely used in chemical enterprises, especially austenitic stainless steel, which has good corrosion resistance and thermal stability. It has an increasing trend in industrial applications year by year. Because it contains high nickel and has a single-phase austenite structure at room temperature, it has high corrosion resistance, high plasticity and toughness at low temperature, room temperature and high temperature, as well as good cold forming and weldability. 304 stainless steel is the most widely used in steel grating production.

Characteristics of 304 stainless steel
The properties of 304 stainless steel flat steel are low thermal conductivity, about 1/3 of carbon steel, resistivity about 5 times that of carbon steel, linear expansion coefficient about 50% greater than carbon steel, and density greater than carbon steel. Stainless steel welding rods are generally divided into two categories: acidic calcium titanium type and alkaline low hydrogen type. Low hydrogen stainless steel welding rods have higher thermal crack resistance, but their forming is not as good as calcium titanium type welding rods, and their corrosion resistance is also poor. Calcium titanium type stainless steel welding rods have good process performance and are used more in production. Since stainless steel has many characteristics different from carbon steel, its welding process specifications are also different from carbon steel. Stainless steel gratings have a small degree of restraint, and are subjected to local heating and cooling during welding, resulting in uneven heating and cooling, and weldments will produce uneven stress and strain. When the longitudinal shortening of the weld exceeds a certain value, the pressure on the edge of the steel grating weldment will produce more serious wave-like deformation, affecting the appearance quality of the workpiece.

Precautions for welding stainless steel gratings
The main measures to solve the overburning, burn-through and deformation caused by stainless steel grating welding are:
Strictly control the heat input on the welding joint, and select appropriate welding methods and process parameters (mainly welding current, arc voltage, welding speed).
2. The assembly size should be precise, and the interface gap should be as small as possible. A slightly larger gap is prone to burn-through or form a larger welding problem.
3. Use a hardcover fixture to ensure evenly balanced clamping force. Key points to note when welding stainless steel gratings: strictly control the energy input on the welding joint, and strive to minimize heat input while completing welding, thereby reducing the heat-affected zone and avoiding the above defects.
4. Stainless steel grating welding is easy to use small heat input and small current fast welding. The welding wire does not swing back and forth horizontally, and the weld should be narrow rather than wide, preferably not more than 3 times the diameter of the welding wire. This way, the weld cools quickly and stays in the dangerous temperature range for a short time, which is beneficial to prevent intergranular corrosion. When the heat input is small, the welding stress is small, which is beneficial to prevent stress corrosion and thermal cracking, and the welding deformation.