How to improve the service life of mandrel?

The quality of mandrel material was improved
To improve the service life of mandrel, the quality of mandrel material should be improved first. Which material properties or metallurgical processes can be effectively improved
High mandrel life?
a. Ductility
a. The lower the content of non-metallic inclusions, the better → improving the deoxidization process of removing inclusions
b. The less the liquid carbide, the better → homogenization at high temperature
c. Grain refinement → tempering after forging
b. Redness
a. Improve the hardness of heat treatment
b. Improving alloy composition
c. Toughness
a. Optimization of quenching process
b. Full tempering
The quality of mandrel material was improved
The manufacturing process of mandrel:
Electric arc furnace (induction furnace) → ladle refining → vacuum degassing → (electroslag remelting) → heat treatment → strong forging → grain refinement →
Annealing → straightening → roughing → heat treatment → straightening → finishing → chromium plating
In the above process, Tianda high core technology mainly adopts different process parameters for the mandrel:
⚫  Process parameters of ladle refining, vacuum degassing and impurity removal
⚫  Heat treatment temperature and time
⚫  Forging, grain refinement process
⚫  Heat treatment scheme

Toughness of steel: it refers to the ability of material to resist stress concentration and prevent crack extension; the toughness of material comes from the uniformity of matrix structure.
Because the matrix of steel is composed of tempered martensite and carbide, the size and distribution of carbides determine its toughness and ductility
◆ The size and distribution of carbides, the content of nonmetallic inclusions and the segregation of microstructure
◆ Heat treatment process and conditions (cooling mode, surface decarburization and tempering timely and fully)
◆ State of working surface (machining scratches, grinding cracks, etc.)

Steel ductility: is the performance of steel metallurgical process quality, is the main index to distinguish different brands of special steel products. Is the material "prefer bending to bending", in the load
The ability of a material to respond to a load by deformation (without cracks) when the load exceeds the elastic strength of the material
The ductility and toughness of special steel are closely related to the uniformity of matrix structure, the content of non-metallic inclusions and the quality of heat treatment process
➢ The smaller and more uniform the liquid precipitated carbides are, the higher the toughness ductility is
➢ The less the content of nonmetallic inclusions, the higher the ductility
➢ The more the martensite transformation and tempering are, the higher the toughness ductility is


Red hardness of steel: it is the ability of steel to maintain strength and hardness at high temperature, which is usually expressed by hardness temperature time curve.
The red hardness of special steel results from the alloy composition and the distribution uniformity of alloying elements in the steel. Recent studies have shown that the heat treatment of the workpiece has a great influence on the red hardness of the material.
➢ Alloy composition and element distribution
➢ Heat treatment process and conditions