Shanghai Ling Sheng Mold Steel Co

Characteristics
, is a chromium-molybdenum-vanadium alloy steel with the following characteristics: high toughness, good wear resistance, good hardenability, dimensional stability during heat treatment, good polishability, good weldability, flame Hardening and high frequency induction hardening properties.

Chemical composition

. . .
Factory state soft annealing to
Application of


Suitable for making cold work molds and plastic molds. Cold stamping dies made of
have high toughness. Made of electrical accessories molds with high wear resistance.

Typical applications
Applications in cold work dies
*General stamping and forming *Punching and forming of thick plates *Deep drawing *Embossing dies *Complex shapes Cold extrusion die * Cold rolling * Shear blade * Prototype tool.
Applications in plastic molds
*High-volume molds *Molds with reinforced plastic materials *Compression molds
The good combination of wear resistance and toughness promotes the suitability for making different molds. The mold made of it has good abrasion resistance, safety and long production life.



Compressive strength
Approximate value at room temperature
Impact strength
Room temperature impact strength after tempering at different temperatures approximation. Quenching temperature ℃, air cooling, tempering twice



Soft annealing
Heat to ℃ in a protective atmosphere and soak for one hour, with each Cool in the furnace to ℃ at a rate of ℃ per hour, then cool in the furnace to ℃ at a rate of ℃ per hour, and then air-cool.
Stress Relief
After rough machining of the steel, if you want to eliminate the residual processing stress, the steel must be heated to ℃, soaked for two hours, then slowly cooled to ℃ in the furnace, and then air-cooled.
Hardening
Preheating temperature ℃
Austenitizing temperature ℃, common temperature ℃
Temperature ℃
Holding time* minutes Hardness before tempering
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*Holding time is the holding time required when the center point of the steel reaches the quenching temperature.
Steel must be protected during the hardening process to avoid oxidation and decarburization.
Quenching medium
*High-speed circulating gas or air *Vacuum cooling (high-speed and sufficient positive pressure gas). *Graded quenching in a salt bath furnace or fluidized furnace at ℃, and then cooled in air. *Oil cooling
Note. Oil cooling is prone to dimensional changes and cracking.
Note. When the mold temperature drops to ℃, it should be tempered immediately
Tempering
According to the required hardness, refer to the tempering curve chart to select the appropriate tempering temperature. Temper at least twice, and immediately cool to room temperature after each tempering. The minimum tempering temperature is ℃, and the holding time is more than 1 hour.
Dimensional changes
Dimensional changes during heat treatment are related to the heat treatment temperature, heat treatment equipment and quenching medium. The size and geometry of the mold also have a great influence, so the mold should leave enough machining allowance to adjust for deformation. The machining allowance of the mold is .%.
The picture below is a test piece with a size of ** mm. The size changes after normal quenching and tempering. Quench at ℃, hold for minutes, air cool.



Some molds undergo surface treatment in order to enhance wear resistance and reduce friction. The most common surface treatments are nitriding and surface coatings, such as titanium carbide and titanium nitride wear-resistant coatings (,).
Gas nitriding and ion nitriding are two commonly used nitriding methods. The temperature of ion nitriding is lower than that of gas nitriding. When the required substrate hardness exceeds, ion nitriding should be used.
Nitriding method Nitriding temperature °C Nitriding time Hours Nitriding layer depth Basic hardness Nitriding layer hardness
Ion nitriding
Gas nitriding
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*The nitriding temperature should be lower than the tempering temperature by ℃
If the nitriding layer is too deep, it will affect the toughness of the mold. Nitriding can be controlled according to the requirements of use. time to adjust the nitride layer depth.
Chemical evaporation coating can also be used, but the temperature cannot exceed ℃. After coating the mold is hardened again.
Physical evaporation coating can be performed at ℃ and ℃. For example, when the temperature of ℃ is used, the hardness of the substrate is higher than that of the coating at ℃. When the temperature of ℃ is used, the bonding force between the coating and the steel is stronger. The temperature should be ℃ lower than the tempering temperature.



The processing parameters listed below are intended to provide a reference for seeking processing conditions. Processing parameters were experimentally obtained from steel in a softened and degraded state.
Lathe processing
Milling machine processing
Surface milling
End milling
, titanium nitride coated high-speed steel Swiss milling cutter, m/min.
, depends on the milling method (side milling or slot milling) and the diameter of the milling cutter.
Drilling
High-speed steel twist drill bit
*Coated high-speed steel drill bit m/min
Tungsten carbide drill bit
, there are cooling pipes and brazed tungsten steel in the drill bit Drill bit, such as or multi-purpose drill bit.
, Adjust according to the diameter of the drill bit.
Grinding
The following are the types of grinding wheels that are commonly used



Take appropriate measures when welding Excellent results can be obtained. . The arc length should be kept as short as possible. The welding rod should be at an angle with the joining edge to reduce undercutting. The welding rod should be at an angle with the forward direction. For large-area welding, the first few layers of welding should be Softer welding materials. Both layers should be welded using the same diameter electrode and the same current. , For large area welding, the mold should be heated and maintained at an appropriate temperature for welding. , The interface should be processed properly in advance.
Argon welding
Electric welding
Heat treatment after welding
The hardened state is lower than the previous tempering temperature ℃ for tempering and softening. The annealed state is heated to ℃ in a protective atmosphere and kept warm. The rate of ℃ per hour is as the furnace is cooled to ℃ and then air cooled.
In order to ensure good polishing and photo-etching effects, welding rods with the same composition as the mold material should be used during welding, that is, welding rods



If electric arc processing is performed in the quenched and tempered state, the mold should be tempered one more time at a temperature lower than the previous tempering temperature