Usually, the plastic mold steel choices include Swedish 8407 and S136; American 420 and H13; European 2316, 2344 and 2083 and Japanese SKD61. For strongly corrosive plastics, S136, 2316 and 420 steels are usually chosen. In addition to S136, 2316 and 420 steels, low corrosion plastics can also choose SKD61, NAK80, PAK90 and 718M steels.mold steel also has a great influence on product appearance . S136, 2316, 718S, NAK80, PAK90 and 420 steel materials are suitable for clear and high polishing surface products, while highly transparent products should primarily select the S136, and secondarily choose the 420 steel materials.
Common Plastic Mold Steel Series:
DH2F
Price：42RMB/KG
Series：Pre-hardened Steel
Hardness：37-42HRC
Manufacturer：DAIDO
Performance & Purpose：
Complex shaped / precision molds & parts
PAK90
Price：66RMB/KG
Series： Hardened up Steel
Hardness：37-42HRC
Manufacturer：DAIDO
Performance & Purpose
High-performance precision plastic injection mold steel; plastic injection mold steel that is resistant to corrosion, strain, and wear, with a highly smooth surface
NAK80
Price：Imported steel :53RMB/KG; Fushun:38RMB/KG
Series：Pre-hardened Steel
Hardness：37-42HRC
Manufacturer：DAIDO; Fushun
Performance & Purpose：
Pre-hardened and corrosion-resistant stainless steel for plastic injection mold, mirror-polished mold; the steel is extremely brittle and easy to crack due to concentration of processing stress when complicated molds are involved. When welding, the hardness of the welded part will decrease, but after aging treatment and air cooling under 500°C temperature conditions for 5 hours, the welded part and the heat-affected area will be of the same hardness with the substrate.
1.2344
Price：Imported steel 55RMB
Series： Hardened up Steel
Hardness：50 ~52HRC
Manufacturer：BUDERUS
Performance & Purpose：
Pressure-resistant hot-working mold steel; excellent machinability and polishing performance, high toughness and plasticity; great wear resistance at high and low temperatures, resistance to thermo-mechanical fatigue and heat. Mold cores, inserts, ejector pins, and sleeves
1.2311
Price：36RMB/KG
Series：Pre-hardened Steel
Hardness：30-34HRC when leaving factory; preheat it for 2-4 hours under 500-600℃ temperature conditions before quenching, then keep it in the 850-880℃ temperature condition for a certain period of time (at least 2 hours); after that, oil cool the steel to 50-100℃ before air cooling; after quenching, the hardness can reach up to 50-52HRC; to prevent cracks, immediately temper it under the 200℃ temperature conditions, after which the hardness can stay over 48HRC, and reach up to 650-700HV (57-60HRC) after nitridation
Manufacturer：BUDERUS
Performance & Purpose：
After thermal treatment, the 2311 pre-hardened plastic mold steel possesses a great processing and polishing performance, and is more suitable for EDM. Generally, it can be used for production of large plastic molds and plastic mold bases.
1.2738
Price：35RMB/KG
Series：Pre-hardened Steel
Hardness：29-33HRC when leaving factory, and can be quenched to 52HRC; carburized hardness is 55-60HRC, nitrided hardness is 650HV (Depth 0.29/.36/.5)
Manufacturer：BUDERUS
Performance & Purpose：
Mainly used in large-size plastic molds and mold bases, such as molds of vehicle bumpers and TV shells. It is suitable for molds that require high gloss and high uniformity, such as the production of hard (PS) and ultra-hard (ABS) rubbers. It is suitable for plastic molds and mold bases of such parts as TV front shell, telephone, water dispenser, and vacuum cleaner.
718
Price：Imported 38RMB/KG; Domestic 20RMB/KG
Series： Hardened up Steel
Hardness：HB: 290-310 when leaving factory, and can be quenched to 48-50HRC, nitrided hardness is 650HV-700HV (Depth 0.29/.36/.5)
Manufacturer：ASSAB; Fushu
718H
Price：Imported 38RMB/KG; Fushun 22RMB/KG
Series： Pre-harden Steel
Hardness：35-39HRC, and can be quenched to 48-50HRC, nitrided hardness is 650HV-700HV (Depth 0.29/.36/.5)
Manufacturer： ASSAB; Fushu
Performance & Purpose：
Suitable for cores, inserts and slides of home appliance and computer molds
738
Price：Imported steel 58RMB/KG; Domestic steel 30RMB/KG
Series： Hardened up Steel
Hardness：37-42HRC
Manufacturer：Saarstahl
Performance & Purpose：
The core steel of general molds, the mold base of high-level molds
738H
Price：Imported 27RMB/KG; Domestic 21RMB/KG
Series：Pre-hardened Steel
Hardness：HB290-330
Manufacturer： BUDERUS
Performance & Purpose：
Used for large-size, long-life plastic injection molds, such as those of home appliances, computer casings and more.
8407
Price：Imported 58RMB/KG; Domestic 30RMB/KG
Series： Hardened up Steel
Hardness：37-52HRC
Manufacturer：ASSAB
Performance & Purpose：
The max. hardness of the heat-treated 8407 reaches up to HRC52. If the min. size of the part is greater than 300mm, the hardness after heat treatment should be kept within HRC50. If the min. size of 8407/8402 materials is greater than 300mm, and a large amount of EDM is required after heat treatment, tempering must be performed to remove stress; if 8407 or 8402 requires nitriding, the heat treatment process is described as follows: first quench the hardness to HRC42-45 (no higher than HRC45), and then nitride the surface to a depth of 0.1mm, the hardness will reach HRC65-68. Suitable for such materials as /PP/PE/PS/POM/PA
420H
Price：Imported steel 68RMB/KG
Series： hardened up Steel
Hardness：48-54HRC
Manufacturer：USA
Performance & Purpose：
The 420 mold steel is applied after being quenched or tempered (Hardness: 48-54HRC). In order to meet the long life cycle requirement or the requirement of producing up to 1 million parts, the appropriate application method should be quenching before low-temperature tempering. Steel quenching is to heat the temperature to 1000-1050 ° C for a certain period of time (30 minutes / 25mm), then oil cool it to 50-100 ° C and immediately temper it to prevent cracking. After tempering at 200 ° C (for at least 4 hours), the hardness can reach over 48HRC, with better polishing and corrosion resistant performances. Applicable to various kinds of plastic product molds, and more suitable for molds with special requirements.
Suitable for production of molds that are used in low acid and humid environments.Suitable for production of transparent plastic products, such as CD, and optical instruments.Suitable for mirror polishing molds.
P20
Price：Imported 18-22RMB/KG; Domestic 11-16RMB/KG
Series：Pre-hardened Steel
Hardness：285-330HB (30-36HRC), nitrided hardness reaches up to 650-700HV (57-60HRC)
1050（50#）
Price：Domestic 6-9RMB/KG
Series：Pre-hardened Steel
Hardness：HB170-220 (HRC17-20)
Performance & Purpose：
The material features low hardness, great tenacity, and poor optical rotation performances, poor wear- / corrosion-resistant, prone to rust, with a low price, mainly used for production of mold bases, unimportant parts, and trial molds; only carburizing can be adopted to improve the surface hardness of the material to HRC52-56. Other thermal treatments, such as quenching and nitriding are not applicable.
SKD61
Price：Imported 55RMB/KG; Domestic 28-38RMB/KG
Series： hardened up Steel
Hardness：56-58HRC nitridable
Manufacturer：Hitachi; Fushun
Performance & Purpose：
The material features low hardness, great tenacity, and poor optical rotation performances, poor wear- / corrosion-resistant, prone to rust, with a low price, mainly used for production of mold bases, unimportant parts, and trial molds; only carburizing can be adopted to improve the surface hardness of the material to HRC52-56. Other thermal treatments, such as quenching and nitriding are not applicable.
H13
Price：Imported 38RMB/KG; Fushun 35RMB/KG;
Series：Hardened up Steel
Hardness：HRC43-45
Performance & Purpose：
The optimal heat treatment condition for the H13 material is to quench it to the hardness of HRC43-45
Beryllium Copper (BeCu)
Price：230-280RMB/KG
Series：Pre-hardened
Hardness：HRC38-43
Performance & Purpose：
The specific application of BeCu in plastic injection molds is to improve the cooling effect in some locations where is relatively thick, so as to prevent shrinkage and other quality defects in these areas.
Porous Steel
Series：Pre-hardened Steel
Price：920-950RMB/KG
Hardness：35-40HRC
Performance & Purpose：
Inserted in a plastic injection mold to help solve ventilation issues. It is usually applied in small quantities as inserts, with standard parts available on the market; the standard porous steel part, i.e. the round bar usually costs no more than 100 RMB, and the cheapest costs only 10 or 20 RMB.
Note:
In terms of resistance to corrosion, POLMAX > S136HSUP > S136SUP > S136H > S136 > 168
In terms of optical rotation performance, POLMAX > S136 > S136H > S136SUP > S136H SUP > 168
Among them, POLMAX can be used to make the molds of various optical lenses; S136 & S136H, various polished molds; and S136SUP & S136H SUP, molds working under highly acidic environments.