E308 electrode can weld cast iron
Stainless steel electrodes can be divided into chromium stainless steel electrodes and chromium-nickel stainless steel electrodes, these two types of electrodes where in line with the national standard, are in accordance with the provisions of the national standard GB/T983-1995 assessment.
Chromium stainless steel welding rod instructions Chromium stainless steel has a certain corrosion resistance (oxidizing acids, organic acids, cavitation) heat and corrosion resistance. Usually selected as power station, chemical, petroleum and other equipment materials. However, chromium stainless steel is generally poor weldability, attention should be paid to the welding process, heat treatment conditions and the selection of suitable electrodes.
1, martensitic stainless steel welding:
Martensitic stainless steel, including chromium-containing 5-9% chromium steel and chromium-containing 12% high-chromium steel. Such steel hardening tendency is large, easy to produce high hardness martensite and bainite after welding to increase the brittleness, residual stress is also larger, easy to produce cold cracks. Therefore, generally must be preheated before welding and interlayer heat preservation, high temperature tempering after welding before cooling.
2, chromium 13 stainless steel welding:
This kind of chromium steel welding hardenability is larger, prone to cracking, if the use of similar chromium stainless steel electrodes (CHK202, CHK207) welding, it must be more than 300 ℃ preheating and post-welding tempering about 700 ℃ slow cooling treatment. If the weldments can not be post-welding treatment, the application of chromium stainless steel electrodes (CHS107, CHS207) and other welding.
3, chromium 17 stainless steel welding:
This type of chromium steel is usually to improve corrosion resistance and weldability and add an appropriate amount of stabilizing elements titanium, niobium, molybdenum, weldability is better than chromium 13 steel, can be used with the same type of chromium stainless steel electrodes (CHK302, CHK307) welding. Before welding, the weldment should be preheated at about 200℃ and tempered at about 800℃ after welding. Can also be used chromium-nickel stainless steel electrodes (such as CHS107, CHS207), no heat treatment after welding.
Chromium-nickel stainless steel welding electrode instructions
Chromium-nickel stainless steel welding electrode has good corrosion and oxidation resistance, it is widely used in the chemical industry, chemical fertilizer, petroleum, food, medical equipment manufacturing. In recent years, with the development of China's industry, chromium-nickel stainless steel welding rod has more than thirty varieties, basically meet the needs of China's construction.
Chromium-nickel stainless steel in welding, subject to repeated heating, easy precipitation of carbide, thereby reducing corrosion resistance and mechanical properties, therefore, chromium-nickel stainless steel welding should be based on the working conditions of the equipment (operating temperature and type of medium, etc.) properly select the electrode, and pay attention to the following matters when using:
1, rust steel electrode flux skin usually have titanium calcium type and low hydrogen type two. Among them, titanium calcium flux skin stainless steel welding rod is generally due to the shallow arc penetration, suitable for thin plate top welding (manual welding), not suitable for all-position welding. At the same time, due to the stainless steel core resistance, AC welding is easier than DC welding red, so as far as possible using DC welding. The low hydrogen flux skin of stainless steel electrode is suitable for all-position welding above the center plate.
2, a variety of stainless steel electrodes in use should be kept dry, titanium calcium flux skin should be 150 ~ 250 ℃ baked for 1 hour, low hydrogen flux skin should be 200 ~ 300 ℃ baked for 1 hour, (can not be repeated drying, otherwise the flux skin is prone to cracking and fall off), to prevent the electrode flux skin sticking to the oil and other dirt, so as not to make the weld to increase the amount of carbon and affect the quality of welding.
3, in order to prevent heating and intergranular corrosion, welding current should not be too large, generally lower than the carbon steel electrode should be about 20%, while the arc should not be too long, the interlayer fast cooling, to narrow channel welding is appropriate.
4, the amount of ferrite in the weld, according to the chemical composition, from Scheufele and Descartes diagram to find.