Method for rapid preparation of metallographic standard samples of high carbon steel

Abstract

The invention discloses a method for rapid preparation of metallographic standard samples of high carbon steel. The high carbon steel is prepared from the chemical compositions in percentage by weight: 0.77-0. 85% of C, 0. 15-0. 35% of Si, 0. 20-0. 40% of Mn, less than or equal to 0. 03% of S, less than or equal to 0. 035% of P and the balance of Fe. The method for rapid preparation of the metallographic standard samples of the high carbon steel comprises the steps that a group of samples are processed, specifically, a sample is taken and placed in a vacuum chamber of a thermal simulation testing machine, and the sample is heated to 780-800 DEG C and heat preservation is carried out; the sample is cooled to the required isotherm temperature at a rate greater than 400 DEG C / s and heat preservation is carried out, then the sample is cooled to a room temperature at a cooling rate of 40-50 DEG C / s, and finally, the metallographic structure of the sample is analyzed by a corrosion sample toobtain the required metallographic standard sample; and the above steps are repeated to obtain metallographic standard samples with different metallographic structures. The operation process is simple, pollution-free and low in cost, and is suitable for rapid preparation of the metallographic standard samples of the high carbon steel.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, in particular to a method for rapidly preparing metallographic standard samples of high-carbon steel. Background technique [0002] The preparation of metallographic standard samples of high carbon steel is generally obtained from austenitized workpieces. Austenitized workpieces are quenched into a hot bath at a certain temperature below the pearlite transformation temperature for a certain period of time, so that the workpieces can obtain Fine pearlite, bainite and martensite structure, and then take out the workpiece quickly or directly cool it in the air or add a tempering process, different isothermal temperature and different isothermal time quenching workpiece can obtain different structures and mechanical properties. Due to the poor hardenability of high carbon steel, the workpiece size should not be too thick. However, thin workpieces are easily deformed or cracked due to the exis...

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Problems solved by technology

In addition, the incubation period of high carbon steel is relatively short during isothermal transformation, requiring the quenching agent to have the ability to rapidly cool the workpiece to avoid austenite transformation before the isothermal temperature, so molten lead is an ideal quenching agent, and in order to facilitate the actual Control, a certain amount of chromium, nickel, copper and other elements will be added in the composition design to improve the hardenability of the steel, prolong the transformation incubation period, and obtain the required workpiece, which undoubtedly increases the cost of the alloy

In addition, because molten lead is more expensive than oil and salt and is volatile and oxidized, it is not easy to remove when it is attached to the surface of the workpiece, which is harmful to the health of the operator and pollutes the environment. It is not recommended to use it more

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