Temperature of choosing the best from the composition detail Thank you D212 component of low carbon steel is a martensitic steel and its constituent carbon content (0.4-0.6%), the total amount of alloying elements in about 5% of the main alloying elements chromium, molybdenum; deposited metal M + A residues, and sometimes a small amount of pearlite, hardness is generally HRC50 welding before welding to be preheated (250-350) ° C and has a good compressive strength, suitable surfacing medium impact wear parts such as gears, , shafts, etc. D707 is a high-carbon high alloy steel, is tungsten carbide, more than 45% of its ingredients generally W (tungsten), carbon (1.5-2.0%). Because the tungsten carbide (WC and W2C), its high melting point, hardness, surfacing when WC is not substantially melted and present in the weld, "inlaid" in the metal matrix, its hardness up to HRC60 or more, a welding Usually without preheating, welding joint stress big should be properly warmed up. The abrasive wear resistance to abrasive wear of this alloy highest performance and heat resistance with moderate impact suitable conditions, such as drilling bits, bulldozer blade.