Austempering is to reduce the deformation of steel pipe and an effective method of quenching crack Jian, but how to properly use the process method should be based on reasonable seamless steel pipe material, size, hardness and toughness, deformation requirements, and specific working conditions the choice will be Isotherml quenching problems that need attention are summarized as follows:
[1] Such as carbon steel and other lower hardenability of steel austempering quenching hardening, should be appropriate to increase the quenching temperature, H is to increase the stability of the austenite to avoid and prevent the occurrence of high-temperature non-shellfish in an austempering quenching process transition’s body.
[2] Austempering restricted steel and pipe size. During austempering quenching quenching, the basic principle is to ensure that change does not happen seamless steel high temperature in the cooling process, and therefore the size of seamless steel pipe steel grades and a direct impact on the quality of the austempering quenching quenching, the general requirements for the carbon steel seamless pipe effective thickness should be less than 5mm, the effective thickness of the alloy should be less than 30mm. From the perspective of the carbon content in the 0.4% to 0.6% of the carbon is not suitable for austempering, higher than 0.6% or more of carbon steel to austempering quenching.
[3] Temperature and time should be based on austempering hardening seamless steel pipe performance requirements, referring to the steel C-curve is determined, in principle, all of the austenite is transformed into bainite, on the cooling medium usually nitrate bath solution in order to ensure a stable temperature, the cooling device should be added in the medium to prevent the increase of the temperature of the medium affects the quality of quenching. Etc. In addition the length of time the temperature should organize the transition end seamless steel pipe as a benchmark, long working efficiency is reduced, and therefore should be taken seriously.
[4] Austempering hardening steel and some may not be tempered. But for some ^’s body hardening of the workpiece, the internal residual austenite will be transformed in the subsequent air cooling process is martensite, must be tempered, the purpose is to eliminate brittleness and stability seamless steel ruler, note the tempering temperature should be below the austempering temperature.
Post time: May-04-2023