Shanghai Ming Yuan Metal Products Co., Ltd. supplies high-quality tool steel 718HH 718HH 718HH imports of hot-work tool steel tool steel mold steel chemical composition 718HH 

 Mold steel - Performance 718HH-718HH steel hardness materials 




 718HH die steel chemical composition: 
 UDDEHOLM 
 UHB ASSAB AISI chemical composition (%) 
 C Si Mn Cr Ni Mo S 
 IMPAX HH 718HH P20 + Ni 0.37 0.3 0.8 1.8 0.9 0.2 0.008 

 718HH die steel factory Hardness: Hardened and tempered to about 330 ~ 370HB. 
 718HH die steel strengths: 
 718HH die steel for the vacuum melting of chromium - nickel - molybdenum alloy steel, hardened and tempered after the factory prior to treatment, with the following expertise: 
 ① deformation and heat treatment without the risk of quench cracking 
 ② without heat treatment costs 
 ③ shorten the molding cycle 
 ④ reduce the cost of mold making (for example, without distortion correction) 
 ⑤ Mold is easy to modify 
 ⑥ can be subjected to nitrogen and flame hardened, the mold surface to enhance the hardness and wear resistance. 
 718HH die steel production has since remain high quality, low sulfur level, the factory has been hard to pre-heat treatment 36-40HRC, so 718HH has the following features: 
 ① excellent polishing and photo-etching properties 
 ② good processing properties 
 ③ high purity and excellent homogeneity 
 ④ wear better, longer die life 
 Note: 718HH have 100% inspection by ultrasonic testing. 
 Large size such as thickness of more than 100mm have been pre-processing, steel milling by the rough surface, to provide users with the convenience of the following: 
 ⑴ save weight 
 ⑵ has been removed off the surface of the carbon steel layer (black) 
 ⑶ standard size (positive tolerance) 
 ⑷ reduce the amount of machining 
 ⑸ no oxide layer, reducing the amount of machining and tool wear 
 718HH tool steel is used for: 
 ① large long-life plastic injection mold, such as home appliances, computer housings and other mold 
 ② High surface finish of the plastic mold 
 ③ blow mold 
 ④ as high hardness, can be used to mold the plastic slide 
 ⑤ forming tools, compressed - braking mode (bending machine model), (depending on production needs may be imposed by flame hardening or nitriding) 
 ⑥ parts and shaft construction 
 718HH the physical properties of die steel: 
 718HH die steel hardened and tempered to 340HB hardness at room temperature and high temperature physical properties: 
 Temperature of 20 ℃ 200 ℃ 400 ℃ 
 Density of 780,077,507,700 
 Coefficient of thermal expansion from 20 ℃ 1 / ℃ --- 12.7 × 10-6 13.6 × 10-6 
 Thermal conductivity W / m ℃ 29.0 29.5 31.0 
 Elasticity N/mm2 205000 200000 185000 
 Specific heat J / kg ℃ 460 --- - 

 718HH die steel tensile strength: 
 Approximate value. 25.4mm diameter round specimens drawn from the hardness 340HB. 
 Test temperature 20 ℃ 200 ℃ 400 ℃ 
 Tensile strength Rm N/mm2 1110 1045 870 
 Yield strength Rp0.2 N/mm2 985 920 775 
 Reduction of area Z% 50 53 54 
 Elongation% 13 14 16 

 718HH die steel EDM (EDM) 
 The final stage of fine EDM should be a small current of high frequency. After the mold surface should be ground discharge place "spark white layer", die in a fire to return to 500 ℃ to remove the stress. 
 718HH mold steel welding 
 Should try to avoid mold welding, welding will increase due to the risk of mold fracture. If welding must die, must die preheating before welding, preheating temperature: 200 ℃ -250 ℃. 
 ** Note: a large welding, after welding to be carried out to deal with stress. 
 718HH tool steel grinding 
 The correct polishing technique to avoid grinding cracks better enhance the mold life. Tempering of the mold on the ground particularly sensitive; grinding wheel must be appropriately amended to cut sharp, as far as possible to choose a more soft, low bonding, open grain of the grinding wheel. Limit the maximum peripheral speed, and use a lot of coolant. 
 718HH polished steel mold 
 718HH pre-hardened steel with excellent polishing performance. Usually aluminum oxide or diamond polishing paste, common steps: 
 1 grinding set aside 0.05mm 
 2.45 No. polished with diamond paste, up to a uniform surface 
 Diamond paste and then polished No. * 
 4.3 No. polished with diamond paste, or paste mold surface finish shall be No. 1 Diamond cream. 
 ** Note: Each polished steel Jieyou most appropriate time; polishing time control, as the hardness of steel and polished skills. Will affect the long polished mold surface finish (eg, cellulite (orange peel) generation). 
 718HH die steel photo-etching 
 718HH die steel with low sulfur content as particularly suitable for photo-etching, the mold surface to ensure uniform and precise pattern.