SKH51 
 SKH51 is a high-speed steel grades of JIS in Japan, equivalent to the German DIN 1.3343, M2 of the United States, China of W6Mo5Cr4V2. 
 Chemical composition (%): 
 C, of ??Mn of Si of Cr Mo V W P S of Ni of Cu 
 0.80 ~ 0.9 0.15 ~ 0.40 0.2 ~ 0.45 3.80 ~ 4.4 4.5 ~ 5.5 1.75 ~ 2.2 5.5 ~ 6.75 ≤ 0.030 ≤ 0.030 ≤ 0.3 ≤ 0.25 

 Features: 
 High red-hot hardness, high wear resistance and cutting ability, high impact toughness, fine uniform grain, high toughness 
 Purposes: 
 Tool industry: scraper, roller cutter, cutter, drill, etc. 
 Forging industry: forging die 
 Industry of screws: Hex, etc. starts with molding, tooth attack, punch 
 Heat treatment temperature and reference methods: 
 Annealing: the temperature of 800 to 880 ° C, 10 ~ 20 ° C / Hr furnace cooling to about 600 ° C, the hardness of HB269 following; 
 Stress relief: temperature 650 ~ 750 ℃, furnace cooling 
 Quenching: 
 Preheat: Temperature 550 ~ 600 ℃ for 30 minutes in every 25mm 
 Preheat: Temperature 850 ~ 900 ℃ for 20 to 30 seconds in each 1mm 
 Warm-up 3: Temperature 1050 ~ 1100 ℃ for 20 ~ 30 seconds every 1mm, suitable for large-scale complex workpieces 
 Austenitic: the temperature of 1170 ~ 1240 ℃ for 10 to 15 seconds every 1mm 
 Quenching medium: oil, hot baths, air or gas; 
 Tempering: 
 The temperature of 540 ~ 570 ℃ for 60 minutes or more per 25mm tempering 3 times more hardness HRC64 or more. 
 Carbon steel is generally used as mold main material used only as an attachment material. 
 The mold ejector commonly used carbon tool steel, such as T10A steel, it is noteworthy to take salt water - oil liquid quenching bending deformation should be replaced by the nitrate bath quenching, quenching or alkaline bath of alkali bath Ms. quenching the three methods the mandrel hardness of 53 to 58 HRC, can reduce the mandrel quenching bending.