Scope of Application
Widely used cold work mold steel, with high strength, good hardenability, and excellent wear resistance, but poor impact toughness. Mainly used for cold stamping dies and punches, cold cutting scissors, drill sleeves, gauges, wire drawing dies, embossing dies, thread rolling dies, etc., which bear small impact loads and require high wear resistance.
Cr12 mold steel belongs to high carbon high chromium martensitic steel, and is also widely used cold work mold steel. This steel has good hardenability, wear resistance, and hot workability. Carbides are well distributed in the steel, making it suitable for manufacturing various cold work molds under complex shapes and heavy working conditions, such as cold stamping dies, thread rolling dies, wire drawing dies, material molds, metallurgical powder molds, woodworking cutting tools, cold cutting scissors, drill sleeves, and gauges. In our research and development, through repeated exploration and experimentation, we have formulated reasonable smelting processes and special ingot molds and forging processes, achieving uniform and consistent material structure. Additionally, for standard material processing, we boldly innovated by adopting a new dual-blade cutting chip process, greatly improving efficiency, shortening cycles, and reducing costs.

Characteristics
1. Vacuum degassing refining treatment results in pure steel quality.
2. Spheroidizing annealing softening treatment, good cutting performance.
3. Reinforced elements of vanadium and molybdenum are specially added, resulting in extremely excellent wear resistance.
Mechanical Properties
Hardness: Annealed, 269-271HB, indentation diameter 3.7-4.1mm; quenched, ≥58HRC
Cr12 Heat Treatment
Metallographic structure: tempered martensite + undissolved carbides + residual austenite.
Delivery Condition: Steel is delivered in an annealed state.
Cr12 Quenching Temperature
Cr12 quenching at 950-1000℃ oil quench, secondary tempering at 550℃
High temperature quenching at 1100-1150℃, low temperature quenching at 960-1050℃, tempering at 550-650℃, the former has secondary hardening phenomenon, tempering not less than 2 times, each time 2h, after tempering can air cool or oil cool, it is best to preheat twice before high temperature quenching, and protective measures should be taken during high temperature heating to prevent oxidation.

Tempering
Cr12 Recommended Specifications
Applications    Heating Temperature/℃    Tempering Time/h    Tempering Times   Hardness (HRC)
Eliminate stress and stabilize structure
Eliminate stress and reduce hardness    180~200
320~350    2
2    1
1    60~62
57~58
Cr12 Quenching
Quenching Temperature/℃    Cooling Medium    Hardness
950~980    Oil    59~63
Processing Technology
Cold work mold steel is mainly used for punching, stretching, bending, cold extrusion, cold heading, thread rolling, and pressing of metal or non-metal materials. Therefore, the molds are required to have high strength, high wear resistance, and sufficient toughness to ensure their service life. Cr12 type steel is widely used as a general-purpose cold work mold in mass production, and its heat treatment methods usually have two types: one-time hardening method (low quench + low temper) and secondary hardening method (high quench + high temper).
The quenching temperature for the one-time hardening method is 1020-1040 degrees, and the tempering temperature can be selected according to the mold requirements. Generally, for cold stamping molds requiring high hardness and wear resistance, low temperature tempering at 160-180 degrees is used, and the hardness after tempering can reach above HRC60. For stamping molds requiring higher hardness and certain toughness, tempering at 250-270 degrees can be used, and the hardness after tempering can reach HRC58-60. For molds that bear higher impact toughness, high temperature tempering at 520 degrees can be used, and the hardness after tempering is HRC55-57.
The quenching temperature of the secondary hardening method is 1080 to 1120 degrees. Due to the presence of a large amount of residual austenite in the steel after quenching, the hardness is relatively low (HRC 42 to 45). Through multiple (3 to 5 times) high-temperature tempering, the residual austenite transforms into martensite, resulting in secondary hardening. The hardness can rise to HRC 59 to 64, mainly suitable for mold parts that require red hardness. The disadvantage is that the impact toughness is relatively poor, affecting the life of multi-stroke molds, so it is not suitable for cold work molds.
Due to the low-temperature tempering used in the primary hardening method, although the hardness can reach above HRC 60, the tempering temperature is low, and the stress relief after quenching is not sufficient. Moreover, during subsequent processing, the surface hardness of the workpiece is prone to decrease due to grinding heat, affecting its service life.
Therefore, the preferred method is medium-temperature quenching + high-temperature tempering, that is, quenching at around 1050 degrees, with a hardness of HRC 63 after quenching. Then, high-temperature tempering at 500 to 520 degrees is applied. Due to the secondary hardening, the hardness after tempering can reach above HRC 60. This process has a lower quenching temperature than the secondary hardening method, resulting in higher strength of the mold after heat treatment, while also possessing certain toughness. Additionally, due to the sufficient stress relief after high-temperature tempering, it is less prone to cracking during subsequent wire cutting and electrical discharge machining, less likely to anneal during grinding, and can be titanium plated, among other advantages, leading to certain applications in production.
Typical examples
1) This steel can be used for silicon steel cold stamping molds, used for deep drawing and punching molds that require high wear resistance and simple shapes under dynamic load conditions.
2) Widely used to make cold work molds with complex shapes, subjected to impact forces, and requiring high wear resistance, such as silicon steel cold stamping molds, thread rolling dies, drawing dies, etc.
3) Used to make concave molds for deep drawing that require wear resistance, with a recommended hardness of 62 to 64 HRC.
4) When used for convex molds for cold extrusion of aluminum parts, a hardness of 60 to 62 HRC is recommended.
5) Used to make convex and concave molds with high wear resistance and complex shapes for bending molds, with a recommended hardness of 60 to 64 HRC.
6) Used for forming carbon with a mass fraction of 0.5% to 0.80% steel plates, with a hardness of 37 to 42 HRC, and a service life of up to 220,000 times.
7) Used for making concave molds for cold heading truck bolts, with part dimensions of Ф8.9mm × Ф9.0mm concentric cylinders, and a service life of only 1,000 to 2,000 cycles.
8) Used for thermosetting plastic molding molds, requiring high wear resistance and high strength.
9) Used for wear-resistant brick forming molds treated with boron + quenching + tempering, compared to the original Q235 steel carbon molds, the service life is increased by 5 to 6 times, with a simple process and significant economic benefits.
10) The solid boron-chromium treated Cr12 steel convex mold has a usage life of up to 160,000 to 170,000 times. The conventional quenching process only has a life of 6,000 to 8,000 times, and boron treatment only has a life of 7,000 to 10,000 times.
11) The Cr12 steel wire drawing plate after vanadium composite treatment increases the mold's service life to 17,000 pieces.
12) The hexagonal mold for cold heading hex bolts made of Cr12 steel, after vanadium composite treatment, has increased the mold's service life by 10 times.