【正文】 osphere and ocean atmosphere. Among them, rural countryside of atmospheric corrosion of mild steel。 the higher the carbon content, the greater the impact of heat treatment. This is because with the increase in carbon content of steel is also a corresponding increase in cementite, different heat treatment systems, the number of cementite precipitates is different from carbon as the cathode of a mixture of carbon steel for nonpassive system, the cathode efficiency increases, will inevitably lead to an increase in corrosion rate. In the carbon content under the same conditions, pearlite morphology and distribution of corrosion to a certain extent, for example, spherical than the flaky pearlite pearlite good corrosion resistance, and its greater dispersion, the average corrosion rate of the more Great. Some of the carbon steel, low alloy steel after heat treatment, materials, mechanical properties and corrosion studied the relationship between that extension of the high rate of steel corrosion resistance of the material useful, and the steel strength, hardness, brittleness and impact the value of changes, and corrosion almost no effect. Elimination of stress and high temperature annealing heat treatment, proved to be useful to reduce the corrosion rate of steel in the original state of the effect of heat treatment has a direct relationship. carbon steel corrosion in the general environment tend to Carbon steel construction, machinery, transport, daily necessities, the most fundamental institution of conventional weapons materials, uses a very wide, with the exception of part of surface treatment, most of them are directly related to environmental exposure, such as air, industrial water, sea water, mud , fertilizer and so on. Therefore, to understand the environment in the carbon steel corrosion in the above trend, with practical significance. Carbon steel in the general atmosphere of dry air or corrosive than the moist air is small, such as the oceanatmosphere climate than the mainland serious corrosion. Carbon steel corrosion rate with changes in environmental factors have changed a lot. In the atmosphere, for example, because of its position, humidity, temperature, airflow and light of the different corrosion rate can be / a varied between. But the majority of cases, / a. Corrosion in aqueous solution was more plex than the atmosphere, most acid, alkali, salt water solution are highly corrosive to carbon steel. Only the strong oxidation of concentrated sulfuric acid, dilute acetic acid, sulfur, saltpeter mixed acid, alkaline hydroxides, alkaline cyanide, alkaline sulfide, as well as nitrate, carbonate, chromate, acetate and ammonia solution and so on, may use the carbon steel at room temperature. In addition, anic solvents such as hydrocarbons, alcohols, amines, aldehydes and ketones, can also be used to make carbon steel containers. Tap water, river water, sea water, distilled water so the corrosion of carbon steel, and water dissolved oxygen, flow, PH value, temperature, bacteria, etc. is different, they are very different。 Sulfide inclusions are plastic, like the distribution of clusters along the rolling direction。 used in fertilizer and oil resistance to hydrogen sulfide steel。s production of lowalloy steel to the following categories: (1) highstrength steel: about twothirds of the total lowalloy steel for more than 18 steel has been officially included in the national standard. Yield strength from 300mpa to 700mpa, initially formed a strength series. Such a wide use of steel to be used for the construction of the Nanjing Yangtze River Bridge, 100 tons of mine dump trucks, 300,000 tons of ammonia synthesis tower, 220,005 1000 kilowatts hydro scroll, 10000ton oceangoing vessels and military ships chemical system, highpressure container and so on. (2) lowtemperature steel: 40105 degree has taken initial shape of the temperature series, and for oxygen equipment and ethylene devices. (3) The corrosion resistance of steel: This type of steel, including resistance to atmospheric corrosion and corrosionresistant steel for sulfuric acid dew point。 other countries, lowalloy steel production usually accounts for steel production of 710%, in 1983 China39。 highcarbon steel is mainly used to manufacture a variety of tools. Carbon steel is divided into ordinary carbon steel and two types of highquality carbon steel, ordinary steel and carbon steel have Group B divided steel. And highquality carbon steel will not only guarantee the mechanical properties, there is need to ensure that chemical position, the phosphorus in steel mixed with sulfur than conventional lowpass steel. The various types of carbon steel in a carbon content of % of the A3 steel or steel production 20 largest and most widely used. Of such steel is greater than the tensile strength of the general 400mpa, the yield strength is greater than 240mpa. Carbon content of less than % of the steel can produce boiling steel. In addition to boiling steel, the steel required to use silicon, manganese alloys deoxidation, and their removal of deoxidation products of most of the floating, but always remains a part of a nonmetallic inclusions. In terms of the carbon steel, carbon steel, nonmetallic inclusions in the type, quantity, morphology and distribution, just the heat treatment system, steel surface conditions, the corrosion would have an impact. This effect is only in the corresponding conditions is parable, and can only be statistical data have actual meaning. Lowalloy steel in the 19th century, 70 years in industry began to apply, but it develops slowly, aware of the late 20th century, 50, because of advances in technology and industrial production of lowalloy steel increased the demand that prompted its rapid and vigorous developed, and now it has bee the