618HH vacuum melted chrome-nickel- molybdenum alloy steel has been quenched and annealed before leaving factory. It has following advantages:
 no risk of crack and deformation in heat treatment;
 no any cost for heat treatment
 shorten the period of making die
 reduce cost (no rectification and deformation)
 easy to correct
 Nitrogenized treatment and flame-hardening treatment is allowed to increase side hardness and wear resistance.


Since produced, 681HH steel has always kept the level of high quality and low sulfur. It has been pre-hardened to 36-40HRC before leaving factory. Therefore, this steel has following characteristics:
 good polishing
 good machining
 high purity
 better wear resistance and longer service life
Remark: 681HH has been completely passed ultrasonic flaw detection.

Large pre-machined steel with thickness over 100mm. More convenience is supplied:
 saving weight
 getting rid of decarbonization coat (dark coat) on surface.
 standard size (positive tolerance)
 reducing mechanical machining
 reducing mechanical machinng and abrasion