Hardfacing is a process of building up of wear and abrasion resisting surfaces. This type of welding, or surface reinforcement as it may be termed, has reached an important stand in modern production work as well as in the field of repair work. It consists in building up, on a surface of a softer metal, a layer or layers of a metal, which will stand, wear abrasion or impact or one that can be used as a cutting surface. A considerable variety of rods is available under Hardfacing heading and the final choice will depend entirely upon the nature of the work. One of the most important types is that containing a high manganese content, and often also nickel and molybdenum, and this type is suitable for building up all types of high (12 to 14%) manganese steel casting, such as tramway, and rail crossing, dredger bucket lips, crusher rolls, steam shovel lips, tractor and caterpillar treads, etc. Certain precaution must be observed in welding manganese casting with these rods. To prevent any cracking, which may develop, the first layers are sometimes deposited on the casting, with rods containing a high chromium and nickel content (as used for stainless steels) and recommended for this purpose.