Heat treatment cryogenic process
What is heat treatment cryogenic process?
In the process of metal material treatment, cryogenic process is an extension of heat treatment, which can transform the retained austenite into martensite and eliminate the treatment internal stress, so as to improve the material properties, hardness, wear resistance and life.
The cold treatment technology of metal materials is a new technology that has improved the performance of metal workpieces in recent years. The so-called cryogenic treatment is to use liquid nitrogen (- 196) as a cooling medium to continue the cooling process of quenched metal materials, to a certain temperature far below room temperature, to promote the further transformation of retained austenite after conventional heat treatment, thereby improving the performance of metal materials. After cryogenic treatment, the wear resistance, toughness and dimensional stability of the metal workpiece can be obviously improved, and the service life of the workpiece can be doubled.
The mechanism of cold treatment of metal materials is as follows:
1. Improve the hardness and strength of workpieces.
Cryogenic treatment, in a sense, is the continuation of quenching, allowing the material with a lower Mf point to continue the transformation from A to M. After conventional quenching, some materials retain austenite up to 25%, or even higher. By continuing the transformation, usually can reach ** RC1-3 degrees, or even HRC 5-6 degrees for many times. The martensite matrix precipitates nanoscale superfine carbides, which improves the hardness of the workpiece. According to the material manual, when the hardness of the material is above HRC50, we can see that the tensile strength of chromium steel, chromium vanadium steel and chromium molybdenum steel usually increases by about 30 MPA for each increase of HRC 0.5 degree.
2. Improve wear resistance of workpieces.
Hardness increases, martensite is more wearable than austenite. When the hardness of materials such as W18CR4V CR12 is increased from HV600 to HV800, the relative wear resistance increases by about 15% to 20% respectively. A large number of ultra-fine carbides precipitated and dispersed in the martensite staggered line and twin band play a pinning and supporting role on the martensite matrix. Even if the hardness of the workpiece is not obviously improved by cryogenic sometimes, we can see the improvement of wear resistance. For high carbon and high alloy workpieces, wear resistance is increased by 50% or more.
Application of heat treatment cryogenic process
Heat treatment and cryogenic process improves wear resistance, releases internal stress, increases dimensional stability and strengthens durability on steel. It is suitable for cutting tools, measuring tools, dies, foundries, hardware, automotive parts, textile parts, precision stamping dies, nanomaterials, precision plastic molds, cutting tools, hobbing cutters, screw punches. Knitting Machine Parts, Precision Springs, Aluminum Alloy Material, Motor Axis, Screw Plate, Powder Metallurgy Mould, Packaging Mould, Tungsten Carbide Material, Pneumatic Tool Parts, Golf Ball Head, Racing Engine, Aluminum Alloy, Copper Alloy, Cemented Carbide, Plastic, Rubber, Asphalt, Glass, Drill Bit for Open Mountain Geology, Oil Nozzle Springs, gears, bearings, saw blades, engine turboshafts, rollers, valves, high-speed tool steels, cemented carbide tools and various drills.