Defects of Vacuum heat treatment quenching
Vacuum quenching technology gradually spread, but also began to point out its problems.
First evaporated Cr, Mn and other alloying elements, and from the heat to the surface of abnormal tissue clamp the work piece by the vacuum vapor deposition cr generated. Measures taken in response. Is to reduce the degree of vacuum, the gas is introduced into the furnace control.
Second, the problem of insufficient cooling capacity of SKH51 punch, with pressurized nitrogen cooling 5 ~ 6Bar of, for SKD6l die casting, with 20Bar super pressurized nitrogen cooling, it is close to be resolved.
Third, deformation hardening, vacuum hardening, quenching deformation is its commodity features, but we all know that this is a false consciousness, although small deformation, recently also tended to improve in order to reduce deformation hardening furnace structure.
Fourth, coloring problem, although the work piece can actually use, but reduces the value of goods, an increase from the mold user claims.
Today, vacuum furnace there are a lot of the heat treatment plant in the vacuum hardening furnace for heat treating bearing rings, will produce deformation of the work piece, SIMUWU vacuum equipment for everyone to do a simple analysis of the deformation of the products in question, and I hope to help everyone .
The first is the use of vacuum hardening furnace before quenching problem, there may be processed before quenching deformation of the bearing rings formed mainly in the following ways:
(1) Cold rolled bearing steel, hot-rolled bearing steel after annealing of the ball according to the specifications required by the mill, cold-rolled into cold-rolled steel corresponding specifications, and then turning forming, or directly turning cold roll forming steel molding, maybe Ways processed residual stress will be relatively larger, it increases the amount of distortion in the subsequent heat treatment.
(2) forging the way, refers to the cold forging steel ball annealing after the first, and then the cold forging or cold grind, and finally turning forming. This approach may also cause deformation of the work piece prior to hardening heat treatment in a vacuum furnace.
(3) forging the way, refers to the steel first by forging ball annealing, cool before turning forming. The same may cause deformation of the work piece before the vacuum heat treatment.
(4) refers to the hot-rolled steel hot-rolled steel to spheroidizing annealing, and then turning way forming.
For the outer diameter of the bearing rings ≤100mm, the current majority grind with cold forming process. This process is due to the energy-saving, can effectively reduce the cost, it is widely used. But the stress produced by this process is relatively large, to the final heat treatment also brings some difficulties. Thus requiring heat treatment process needs to be more precise, the operation to be more serious, while equipment for the heat treatment (optional SIMUWU vacuum hardening furnace can meet the requirements) are also more demanding, and only then will we be able to achieve the required product technical Claim.