Aging treatment During aging treatment, copper rich phase precipitates from martensite, making the steel precipitation hardening. At this time, the shrinkage rate of steel parts is 0.04%~0.06%. The more precise the workpiece is, the more consideration should be given to machining the valve seat after heat treatment. Heating can be carried out in atmosphere or vacuum. In case of atmospheric environment, oxide skin on the surface shall be considered. During aging treatment, rapid cooling is prohibited after forging to prevent forging cracking, and furnace cooling, pit cooling, or sand cooling shall be adopted. It is known that the surface hardness test result of Stellite NO.6 surfacing on 2Cr13 is 379HB. However, the surface hardness of the valve seat is more than 50HB different from this hardness, so 17-4PH steel sample is used for heat treatment test. The effective temperature is about 620 ℃. Even if the workpiece is used in the harsh marine environment, there will be no stress corrosion cracking, which means it has the effect of stress relief heat treatment. If the aging temperature is 620 ℃, its stress corrosion cracking resistance is superior to other precipitation hardening stainless steels in acidic chloride solution containing H2S.

Application and advantages of pneumatic butterfly valve
Pneumatic butterfly valve, wire maintenance pipe for installing optical cable, fine optical ruler, optical measuring instrument, medical instrument, machine equipment, remote water meter, door magnetic alarm and other equipment that need to stop safety protection for wires, maintenance pipe for various small wires, and network wire maintenance pipe for various computers, machine operators, etc.
The pitch is sensitive, with good flexibility, no blocking and stiffness, light weight, good caliber divergence, flexibility, repeated bending, good flexibility, soft and smooth, easy to position the threading device.