The annealing of cold-drawn flat steel is a metal heat treatment method that heats the steel to a temperature where a phase transition or partial phase transition occurs, keeps it warm for a period of time, and then cools it at a suitable speed in a furnace or buried in a furnace or in a medium with poor thermal conductivity.

The annealing of cold-drawn flat steel is not only to eliminate and improve the tissue defects and residual stress left over from the previous process, to prevent deformation and cracking of the workpiece; to soften the steel for cutting, refine the grain, and improve the organization to improve the mechanical properties of the workpiece; and to prepare for subsequent processes.

Annealing is the heat treatment of semi-finished products, also known as pre-heat treatment.Normalizing is a heat treatment method that heats steel above the critical temperature, converts all steel into an average austenitic, and then cools naturally in the air.If the annealing method of flat steel is not mastered properly, it will affect the quality and performance of flat steel.

When cold-drawn flat steel controls the cold-drawing of steel bars at the cold-drawing rate, the control value must be determined by the test.Requirements for test and measurement: there must be no less than 4 test specimens in the same batch in the same furnace. Each specimen must be measured according to the cold tensile stress specified in the specification. The corresponding cold tensile rate, and the average value of the specimen is taken as the actual cold tensile rate of the batch of steel bars in the furnace.If the strength of the steel bar is too high and the average cold drawing rate is less than 1%, the cold drawing rate of 1% should still be controlled when the steel bar is cold drawn.

The use of cold-drawn flat steel is relatively common, and it is well used in many fields. When this product is produced, there are many guidelines to be followed and aspects to be paid attention to.

①Adhere to the combination of theoretical ingredients (ingredient calculation) and practical experience.Regardless of whether the test algorithm or the graphical method is adopted, the theoretically calculated ingredient data cannot be determined as the ratio, and it is necessary to master the law of change of elements in the melting process of the intermediate frequency furnace.If the lining is an acidic material and the temperature of the liquid iron is 15001, only the lower limit can be taken in the amount of 31, and the lower limit must be taken for carbon.

② Grasp the chemical composition of various metal materials entering the furnace and the burning and reduction laws of each element.Strict requirements for clear composition are put forward for the classification, stacking and numbering of returned iron (pouring risers, scrap castings).The reduced elements in the furnace are subtracted when the ingredients are made, and the burned elements in the furnace are made up when the ingredients are made up.

③The alloying elements in the cold-drawn flat steel ingredients are based on the principle of one-time addition. The middle limit is taken for other ingredients other than 3. 42CrMo round steel 0, 3, etc. can be added after melting and clearing the slag, and it will burn less in an acid furnace.

④Control of 0 and 3 content.The amount of 0 and 3 is mainly derived from the new iron. The amount of 0 and 8 can be controlled within the required range by selecting the charge, so it is necessary to make the amount of 0.06 and 04 of the new iron so that when calculating the ingredients, the amount of 0 and 8 can not be considered, due to the different technical requirements of castings.