Metal heat treatment is one of the important processes in mechanical manufacturing. Compared with other processing processes, heat treatment generally does not change the shape and overall chemical composition of the steel product, but changes the micro-structure inside the item or changes the chemical composition of the surface, thus endowing or improving the performance of the product. The purpose of metal heat treatment is to improve the intrinsic quality of the metal so that it has the required mechanical properties, physical properties and chemical properties. In addition to the reasonable selection of materials and various forming processes, heat treatment processes are often essential. Steel is the most widely used material in the mechanical industry. The micro-structure of steel is complex and can be controlled through heat treatment. Therefore, the heat treatment of steel is the main content of metal heat treatment.

Carbon steel is an iron-carbon alloy with a carbon content of 0.0218%-2.11%. It generally contains small amounts of silicon, manganese, sulfur, and phosphorus. The higher the carbon content in carbon steel, the greater the hardness and strength, but the lower the plasticity. 

Export tax rebate is a common tax measure in international trade, aiming to encourage fair competition in the export of goods from various countries. Under WTO rules, export tax rebates comply with the principle of national treatment. However, on November 15, 2024, the Ministry of Finance and the State Administration of Taxation of China announced that starting from December 1, 2024, the export tax rebates for 34 tax codes for copper materials and the export tax rebates for 24 tax codes for aluminum materials will be canceled.

Stainless steel is a common metal material that has excellent corrosion resistance and aesthetics, and it is widely used in various fields. The most basic characteristics of stainless steel are its rust resistance under atmospheric conditions and corrosion resistance in various liquid media. This characteristic is directly related to the chromium content in the steel. The presence of chromium causes an invisible film to be formed on the surface of the steel, which can prevent oxidation and make the material "passivated" or resistant to corrosion. Adding other elements such as nickel or molybdenum can improve corrosion resistance, strength and temperature resistance. In order to further enhance the function and appearance of stainless steel, it is often necessary to perform surface treatment. This blog will shed light on the common surface classifications of stainless steel over the past few years.