1.2312 Plastic Mould Steel P20+S
1.2312 plastic mould steel is a pre-hardened mould steel with excellent machinability, balanced toughness, good wear resistance, and stable performance for general plastic mould applications. It is widely used for plastic molds, mold frames, injection molds, and other tooling parts that require efficient machining, reliable service life, and cost-effective performance, especially where high mirror polishing and corrosion resistance are not the main priorities.
Product Description
Xiri Tool Steel is a leading supplier of DIN 1.2312 plastic mould steel (AISI P20+S) in China. 1.2312 mold steel is a pre-hardened plastic mold steel. Due to the addition of sulfur, it has excellent machinability. It is often used to make plastic molds and mold frames that do not have high requirements for polishing performance, but its corrosion resistance and mirror polishing ability are relatively weak.
Whether you need 1.2312 flat bars, P20+S steel plates, or forged rounds, we provide custom dimensions with machining or grinding services. Our materials are strictly tested to ensure premium metallurgical structure.
1.2312 is a high-quality plastic mould steel that undergoes pre-hardening treatment (typically pre-hardened to 28-34 HRC). Formulated with a refined alloy composition (primarily containing carbon, chromium, manganese, and other elements), it undergoes specialised smelting and heat treatment processes to achieve a hardness range suitable for direct machining upon delivery. This eliminates the need for cumbersome secondary heat treatment, significantly shortening the mould manufacturing cycle and accelerating project implementation.
Chemical Composition of DIN 1.2312 / AISI P20+S mould steel
| C | Si | Mn | Cr | P | S | Mo |
| 0.35-0.45 | 0.30-0.50 | 1.40-1.60 | 1.80-2.00 | max 0.030 | 0.05-0.10 | 0.15-0.25 |
Supply Form & Size Range of 1.2312 / AISI P20+S mould steel
We supply 1.2312 / P20+S steel in various forms to meet your manufacturing needs:
Round bar: Diameter 10mm – 800mm
Steel Plate / Flat: Thickness 5mm – 800mm x Width 100mm – 1800mm
Surface: Black, Peeled, Rough machined or Grinded.
Delivery Condition: Annealed or Quenching +Tempering
Core Performance of 1.2312 P20+S Mould Steel
Superior polishing performance and surface finish: Its pure, uniform internal structure facilitates high-grade mirror polishing (e.g., #12000 grit and above), meeting the stringent surface gloss requirements for automotive interior components, optical lenses, and appliance panels. This reduces post-processing and enhances product aesthetic quality.
Outstanding Etching Pattern Machinability: The material’s fine texture yields crisp, sharp etched patterns with exceptional texture reproducibility, making it an ideal mould material for producing decorative plastic products featuring leather grain, wood grain, geometric patterns, and more.
Balanced mechanical properties and wear resistance: The pre-hardened state delivers an optimal combination of strength and toughness, effectively resisting high-pressure erosion and filling wear from molten plastic. This extends mould service life while reducing maintenance frequency and costs.
Good corrosion resistance: Contains an appropriate level of chromium, providing resistance to gases released during the processing of corrosive plastics like PVC. This minimises the risk of surface rusting and safeguards mould precision.
Superior machinability: Pre-hardened to a moderate and uniform hardness, it exhibits excellent performance in turning, milling, drilling, grinding, and electrical discharge machining (EDM). This significantly enhances machining efficiency, reduces tool wear, and shortens mould delivery times.
1.2312 Wide-ranging applications covering core requirements
Thanks to its comprehensive properties, 1.2312 has become the material of choice for numerous plastic product moulds, particularly suited for:
High-gloss finish moulds: Automotive lamp covers, interior trim components, LCD display housings, cosmetic packaging.
Complex textured moulds: Home appliance panels (simulated metal brushing, leather grain), consumer goods (simulated wood grain, fabric texture), toys.
Long-life general-purpose injection moulds: Electronic/electrical enclosures, office equipment components, large industrial parts.
Transparent component moulds: Optical lenses, light guides, transparent containers (delivering outstanding performance in applications requiring highly polished transparent parts).
Our advantages in Processing 1.2312 Mould Steel
We understand that the quality of mould steel is fundamental to your project’s success. To ensure every batch of 1.2312 mould steel meets the most stringent standards, we implement comprehensive precision control from raw material sourcing to finished product:
Select Raw Materials and Advanced Smelting: Utilising premium raw materials, we employ electric arc furnace (EAF) smelting combined with ladle refining (e.g., LF, VD) or the purer electroslag remelting (ESR) process. This effectively reduces sulphur, phosphorus, and gas content while minimising non-metallic inclusions, establishing the foundation for high material purity and uniformity.
Precision forging/rolling and microstructure optimisation: Employing scientifically rational forging or rolling techniques, we achieve thorough grain refinement, dense microstructure, and elimination of internal defects. This ensures the material possesses excellent isotropic properties and consistent machinability.
Precision Pre-hardening Heat Treatment: Conducting quenching and tempering under stringent process parameter control, utilising advanced temperature regulation and cooling techniques. This guarantees uniform hardness (typically controlled within ±2 HRC across the entire length) and stable mechanical properties, meeting direct machining requirements.
Comprehensive non-destructive testing: Employing methods such as ultrasonic testing (UT) to conduct 100% internal inspection of the steel, effectively identifying and eliminating potential defects including cracks, shrinkage cavities, and inclusions, thereby guaranteeing material integrity.
Rigorous dimensional and surface control: Precise management of steel tolerances and straightness, complemented by surface finishing treatments (e.g., peeling, polishing) to deliver a smooth surface condition, facilitating subsequent machining and application.
Not sure about the best equivalent for your application?
Why Manufacturers Choose Huangshi Xiri
Huangshi Xiri combines international-standard steel grades, a complete tool steel portfolio, strict quality control and reliable global supply. We match DIN / JIS / AISI equivalents precisely, offer cutting and heat-treatment services, and control every step from smelting to inspection. With stable capacity, on-time delivery and responsive technical support, we help manufacturers reduce risk, save costs and run production with confidence.
Contact Us
Contact Huangshi Xiri today for quotations, grade selection and technical support on tool steel, mold steel and alloy steel. Whether you need samples, cutting-to-size service or long-term supply for your projects, our engineers and sales team are ready to respond quickly with professional advice and reliable solutions for your manufacturing needs.
