What are Basic Low-Hydrogen type of MMAW electrodes?
This covering has high content of Calcium Carbonate (in the form of limestone, calcite or marble) and Calcium Fluoride (in the form of Flourspar). This results in a chemically basic slag which is fairly fluid. Use of organic materials such as cellulose and minerals with chemically combined water (such as china clay, talcum and mica) are avoided in order to keep the arc hydrogen free. This type of coating is called the low-hydrogen type. The gaseous atmosphere formed around the arc consists of CO, CO2 and F compounds. The basic characteristics of the slag results in good transfer efficiency of the alloying elements from the coating to the weld deposit. The so-called hydrogen controlled mild steel electrodes are generally made with this type of coating, and this coating is also preferred in low-alloy high tensile electrodes, in order to minimise the risk of hydrogen-induced cracking or cold cracking in the base metal. The popular Basic coated electrodes use potassium as binders for use i
