4Cr13
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4Cr13, as a high-carbon martensitic stainless steel, with 13% Cr corrosion-resistant substrate and optimized heat treatment process as the core
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Product Description
4Cr13, as a high-carbon martensitic stainless steel, with 13% Cr corrosion-resistant substrate and optimized heat treatment process as the core, is irreplaceable in acidic environment molds (PVC/medical), high-finish scenes (optical lenses) and wear-resistant parts (tools/bearings). Through the control of Mo microalloying + Cr/C ≥ 33.5, the annealing hardness is reduced to ≤ 200 HBW (improving machinability), and the pre-hardened steel (30 ~ 36 HRC) is directly processed without heat treatment, so the comprehensive cost performance is significantly better than that of ordinary 420 steel.
Smelting method
-- EF + LF + VD: deep desulfurization by LF (S ≤ 0.030%), removal of hydrogen/oxygen gas by VD (O ≤ 20 ppm), improvement of purity.
Innovative process (high-end type): Some manufacturers adopt steel ingot rolling + shorten rolling annealing interval to optimize grain uniformity. Optional upgrade: Electroslag remelting (ESR) to further improve purity (such as high-end medical equipment steel).
Process characteristics
Heat treatment process:
Annealing: ordinary annealing: heat preservation at 780 ~ 820 ℃ for 8 ~ 12 hours, slow cooling to below 400 ℃ at ≤ 30 ℃/H, hardness ≤ 200 HBW (optimized machinability);
Isothermal spheroidizing
annealing: 905 ℃ × 2 H austenitizing + 750 ℃ × 8 H isothermal, carbide spheroidization rate > 78%, hardness ≈ 192 HBW;
Quenching: oil cooling at 1050 ~ 1100 ℃ to obtain martensite matrix with hardness ≥ 50 HRC;
Tempering: fast cooling at 200 ~ 300 ℃ (the best corrosion resistance), avoid tempering at the secondary hardening peak (near 500 ℃) to prevent carbide coarsening;
Pre-hardening innovation: adding 0.01% ~ 0.10% Mo and controlling Cr/C ≥ 33.5, annealing hardness ≤ 200 HB, reaching 30 ~ 36 HRC after pre-hardening, improving machinability.
Forging process Preheat 650 ~ 750 ℃, initial forging 1130 ~ 1150 ℃, final forging ≥ 800 ~ 850 ℃, avoid cracking.
Purity
Key indicators
Ultra-low impurities: phosphorus (P ≤ 0.030%), sulfur (S ≤ 0.030%), non-metallic inclusions ≤ Grade 2.0 (GB/T 10561);
Gas control: hydrogen content after vacuum degassing ≤ 2.0 ppm, proportion of large-size inclusions (> 5 μm) in ESR process ≤ 20%
High-end level:
flaw detection of steel for medical equipment reaches SEP1921 E/e level (defect ≤ Φ1 mm equivalent)
Micro-structure
Annealed state: spherical pear-lite + uniform fine carbide (such as Cr7C3); Quenched and tempered state: tempered martensite matrix + dispersed carbide, no network carbide;
Grain size: ASTM 8 ~ 10 grade (fine grain ensures high toughness) ;
Impact work
mechanical properties show that: Tensile strength ≥ 520 ~ 590 MPa, elongation ≥ 15% ~ 20%;
High toughness performance: suitable for impact load scenarios (such as die-casting dies, valve bearings) ;
Ultrasonic Flaw Detection
ASTM A388/SEP 1921;
Level:
Ordinary grade: defect ≤ Φ2 mm equivalent;
High quality (medical/precision mold):
defect ≤ Φ1 mm equivalent (E/e level);
Ex-factory status
Annealed state: hardness ≤ 201 ~ 230 HB (smooth round, black fur round surface, etc.);
Pr-hardening state: 30 ~ 36 HRC (to be customized by protocol);
Size specification
Round steel Φ 20-350 mm × 1-6 m; Precision thimble, mold core;
Plate thickness 16-300 mm × width 100-1000 mm; Large form-work, medical equipment;
Square steel 50 × 50 ~ 300 × 300 mm; Special for insert;
Main features
High corrosion resistance: Cr content 12% ~ 14%, forming a passive film, resistant to PVC decomposition acid (HCl/HF) and organic acid corrosion, superior to ordinary die steel.
Mirror polish-ability: pure fine grain structure, polishing up to Ra ≤ 0.05 μm (applicable to optical lens and household appliance shell).
High hardness and wear resistance: the hardness after quenching is ≥ 50 HRC, and the wear resistance prolongs the service life of the die by 30% + 16.
Dimensional stability: low deformation rate in pre-hardened state, suitable for precision assembly.
Product Application area
Industrial area: suitable for discharge, grinding processing, suitable for high mirror surface and high precision injection mold cavity, after heat treatment, it has high hardness and toughness, it can also be used for stamping mold accessories, templates, etc., and there are requirements for the surface of contact products, such as fixture molds, etc. It is generally suitable for high temperature rust prevention and corrosion prevention.
Consumer area: 4Cr13 is also used in the manufacture of surgical instruments, cosmetics, tableware, scissors and other daily necessities. Its excellent corrosion resistance and high hardness make it outstanding in these fields.
Plastic mold: home appliance shell (TV, refrigerator), toys; high finish + corrosion resistance;
Medical equipment: hyperbaric oxygen chamber, mask machine, surgical instruments; Organic acid corrosion resistance + sterile surface;
Precision optical parts: lens, CD mold; Ultra-mirror polishing;
Industrial components: hot oil pump valve plate, spring, bearing; High hardness + wear resistance;
Packing and shipping
Generally, packing and transportation will be arranged according to the customer's requirements, whether to pack and arrange the appropriate mode of transportation, vehicles, such as whether to directly load and transport, whether to pack steel belts, whether to pack and spray marks, etc.


Keywords:
4Cr13
FAQ
Q How should I choose the right die steel material for my die?
Ans: There are several key factors to consider when selecting a die steel, including: Mold use: injection molding? Die casting? Stamping? Cold work? Hot work? Processing material: plastic type (including glass fiber?) , metal type, yield requirements. Performance requirements: wear resistance, toughness, corrosion resistance, high temperature strength, polishing, dimensional stability. Budget: The price of different material grades varies greatly. Processing conditions: working temperature, stress, cooling mode. Suggestion: Provide as much detail as possible about the application of the die, or contact our technical sales team directly, and we will recommend the most suitable material grade according to your specific needs.
Q Is the die steel provided by you genuine? How to ensure the quality of materials?
Ans: Yes, the die steel we provide is produced and processed independently. We have long-term cooperation with first-line brands at national and abroad to ensure that all materials are genuine. We provide a complete original warranty (material certificate), including key data such as chemical composition and physical properties. We will also carry out strict factory re-inspection of some materials to ensure that the quality meets the standards.
Q The price of die steel fluctuates greatly. What are the main factors affecting the price?
Ans: The price of die steel is mainly affected by the following factors: Raw material cost: market price fluctuation of alloy elements (such as chromium, molybdenum, vanadium, tungsten, etc.). Production process: ESR, VD/VAR and other special processes increase the cost. Grade and brand of material: The price of material with high performance and famous brand is higher. Specifications and sizes: Premium prices may apply for special sizes, large sizes, or small quantities. Market supply and demand: changes in supply and demand in global and regional markets. Processing state: the price of pre-hard state (such as P20, 718, NAK80, etc.) Is higher than that of annealed state. We will provide a transparent and reasonable quotation according to the market situation.
Q What is time for delivery?
Ans: The delivery time depends on: Material inventory status: Common brands and specifications We usually have in stock, can achieve faster delivery (for example: 1-3 working days). Material specification and status: special size, uncommon brand or special treatment (such as pre-hardening, deep processing) may need to be ordered, the cycle is relatively long (for example: 1-6 weeks). Order size: Large orders may require coordinated production scheduling. Please tell us your specific requirements (brand, specification, status, quantity) at the time of inquiry, and we will provide the most accurate delivery information.
Q Can you provide heat treatment or processing services after the purchase of die steel?
Ans: Yes, we provide complementary professional services: Heat treatment: With professional heat treatment equipment (vacuum quenching, cryogenic treatment, tempering, etc.) And strict process control, we can provide customers with precise heat treatment services (according to material brand and hardness requirements). Finish machining: We can provide precision machining services such as milling, grinding (surface grinding, internal and external grinding), wire cutting, EDM, etc. According to customer's drawings. Please provide your specific needs (drawings, technical requirements), and we will evaluate and provide quotations and service programs.
Q The mold cracks and wears too fast during use. What are the possible reasons? Is it related to the material?
Ans: The causes of mold failure are complex and diverse, which may be related to materials, but also involve many links such as design, processing, heat treatment, service conditions, etc.: Material factors: improper selection of materials (performance does not match the working conditions), internal defects of materials (inclusions, segregation), counterfeit and shoddy materials. Heat treatment factors: Improper process leads to poor structure, uneven hardness and excessive residual stress. Design/processing factors: stress concentration, poor surface roughness, too deep tool marks. Usage factors: overload, insufficient lubrication, poor cooling, improper maintenance. Suggestion: In case of failure, please provide detailed information as much as possible (material grade, heat treatment status, photos of failure location, description of working condition). Our technical team can assist you in preliminary analysis to determine whether it is related to the material or provide suggestions for improvement.
Q Do you have a minimum order quantity (MOQ) requirement for your die steel products?
Ans: For the stock of conventional grades and specifications, we usually do not have strict MOQ restrictions, and can be purchased according to the actual needs of customers. For materials requiring special orders (such as unusual grades, special sizes, customized heat treatment/processing), Certain MOQ requirements may be set to ensure the economy of production, usually a minimum of 8 tons. Please consult our sales staff for specific MOQ before placing an order.
Q In addition to standard grades, can you offer special die steels with custom compositions?
Ans: We mainly deal in standard grades of die steel, which are widely proven to meet the needs of most applications. For the development of customized alloys with special performance requirements, this usually involves a large amount of R & D investment and production coordination, which is costly and takes a long time. We recommend that priority be given to the material closest to the demand from among the existing mature grades, or to meet special requirements by optimizing the heat treatment and surface treatment. If there is a need for customization, please specify the technical requirements and we will evaluate the feasibility.
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