(1) Decarburization (reducing service life)-1. Use a salt bath furnace or a heating furnace for heating. 2. Adopt rapid heating process.
(2) After quenching, the hardness is insufficient, the number of non-martensite is large, and ferrite appears in the core (to produce total residual deformation and reduce service life)-1. Use materials with better hardenability. 2. Improve the cooling capacity of quenching coolant. 3. The temperature of the spring entering the coolant should be controlled above Ar3. 4. Appropriately increase the quenching heating temperature.
(3) Overheating (increased brittleness)-1. Strictly control the heating temperature of forming and quenching. 2. Strengthen the metallographic inspection during quenching.
(4) Cracking (increased brittleness, severely reduced service life)-1. Control the quenching heating temperature. 2. When it is cooled to 250-300C during quenching, take out air cooling. 3. Tempering in time