High-precision cold-drawn pipe in the production and processing requirements are very high. High-precision cold-drawn tubes are under the action of heat, because the surface temperature is relatively high, the contraction speed is relatively fast, and the speed of condensation is also relatively fast, which is easily affected during the process of condensation. In order to obtain good chemical and physical properties, heat treatment of high-precision cold-drawn tubes is required.
The faster the cooling rate, the higher the carbon content and alloy composition, the greater the uneven plastic deformation generated under the thermal stress during the cooling process, the greater the residual stress formed. On the other hand, due to the change in the structure of the steel during the heat treatment process, that is, when the austenite is transformed into martensite, the increase in specific volume will be accompanied by the expansion of the volume of the high-precision cold-drawn tube, and the parts of the workpiece will be transformed in sequence, causing the volume to grow Not the same and cause tissue stress. The change of tissue stress is that the tensile stress on the surface is just opposite to the thermal stress. The magnitude of the structural stress is related to the cooling rate, shape and chemical composition of the workpiece in the martensite transformation zone.
The heat treatment process of high-precision cold-drawn tube is related to the hardness of high-precision cold-drawn tube, and the volume is also related to its processing technology.