Carbon Steel Weldability
Date:2018-01-16 View:391 Tag:Carbon Steel Weldability
Welding method is under the conditions of welding materials, according to the design requirements of the welding components, and can meet the requirements of the scheduled service. The four factors are affected by the welding material, welding, the type of part and the usage requirements.
Low carbon steel welding
Due to the carbon content of low carbon steel, manganese, silicon content is less, so there is usually no serious welding hardened tissue or tissue. Low carbon steel welded joints have good plasticity and impact toughness, generally do not preheat during welding, control the temperature and heat between layers, and do not improve the microstructure after welding heat treatment. The welding process is not required to be adopted in the whole process and the weldability is good.
Medium carbon steel welding
Carbon steel carbon mass fraction of 0.25% to 0.60%. When the carbon and manganese content close to 0.25%, the mass fraction is not high, good weldability. As the carbon content increases, the weldability deteriorates. If the carbon content is about 0.45%, when using low-carbon steel welding process welding, the heat-affected zone may have brittle martensite, easy to crack, the formation of cold cracks. During welding, the amount of matrix material is melted into the weld to increase the carbon content of the weld, thereby promoting thermal cracking in the weld, especially when sulfur impurities are strictly controlled. Such cracks are more sensitive in the crater because of the heat distribution in the weld cracks and many wavy lines perpendicular to the weld.
High carbon steel welding
When the carbon content of high carbon steel is more than 0.60%, the weld crack is more susceptible to hardening after being hardened so that the weldability is poor and can not be used for the manufacture of welded structures. Need to be more commonly used in the manufacture of hardness or wear parts, welding work is mainly welding repair. As high-strength carbon steel mainly in the 675mpa above, so the common electrode model e7015, e6015, optional E5016, E5015 electrode structure when the members require too much. In addition, we can also use chrome-nickel austenitic steel welding rod. Due to high carbon steel parts in order to obtain high hardness and wear resistance, the material itself to be heat-treated, the welding should be annealed before welding. Before welding should be preheated, preheating temperature is generally between 250 ~ 350 degrees, the welding process shall not be less than the preheating temperature between the insulation layer. The heat of the slow cooling of the weldment after welding requires the stress relieving heat treatment at 650 ℃ immediately into the furnace.