D557 valve welding electrodes meet the GB EDCrNi-C-15 
 Description: D557 is a low hydrogen sodium type coating CrNiSi valve welding electrodes, welding of metal depend on a large number of silicon intensive, get austenite + ferrite, with the aging time increased, hardness and resistance to abrasion further improved performance, deposited metal has good resistance to corrosion, oxidation resistance and corrosion resistance, the use of DCRP. 

 Uses: temperature lower than 600 ℃ for the high pressure valve sealing surface surfacing. 

 Chemical Composition of Deposited Metal (%) Chemical Composition C Mn Si SP Ni Cr 
 Guaranteed value ≤ 0.20 2.00 ~ 3.00 5.00 ~ 7.00 ≤ 0.030 ≤ 0.040 7.0 ~ 10.0 18.0 ~ 20.0 

 Surfacing layer hardness: HRC ≥ 37 
 Reference Current (DC +) electrode diameter (mm) φ3.2 φ4.0 φ5.0 
 Welding current (A) 80 ~ 120 120 ~ 160 160 ~ 200 

 Note: 
 1. 300-350 ℃ before welding electrodes shall be baked 1h. 
 2. The higher the hardness of deposited metals, so the surfacing of the workpiece according to size, shape, different cooling measures to moderate preheating temperature, preheating temperature is generally 300-450 ℃, as far as possible when short arc welding, small current.