Medium carbon steel generally refers to the carbon content of about 0.25 to 0.60% carbon steel. Manual arc welding of carbon steel casting and welding of the main features as follows:

(1) Base metal near the weld area prone to low plasticity of hardened tissue. The higher the carbon content, plate thickness, the greater the tendency hardened. Weldment stiffer, faster cooling and rod selection is not the time, prone to cold cracking.

(2) Since the base metal melted into the first layer of weld metal ratio of about 30%, so the higher the carbon content of the weld, the result is easy to weld metal hot cracking and cold cracking.

Measures taken by the welding of carbon steel

(1) If possible, choose a basic low-hydrogen electrodes. Such electrodes and high resistance to cold cracking resistance to thermal cracking capacity. Individual cases, by strictly controlling the preheating temperature and minimize a reduction of the base metal penetration weld carbon content and other process measures, the use of calcium ilmenite type electrode may also get satisfactory results. When the strength of welded joints and base metal does not require equal time should be used in low-intensity basic low hydrogen electrodes. Such Weld Weld plastic, produce cold cracking and thermal cracking of less dangerous.

(2) Preheat the main technological measures welding and repair welding of carbon steel, particularly the thickness of the weldment, rigidity is large, warm-up in favor of reducing the maximum hardness of the heat affected zone and prevent cold cracking, and can improve joint plastic. Overall warm-up and proper warm-up also reduces local post weld residual stress. The carbon content of different welding carbon steel welding preheat temperature and no uniform rules. This is not only because the choice of the preheating temperature is determined by the carbon content of the electrode, but also affected by other factors, such as the size and thickness of weldment, welding type, the welding parameters and the stiffness of the structure and so on.