外文翻译--金属热处理

外文原文

Metal heat treatment

Metal heat treatment is a kind of craft to heat pieces of metals at the suitable temperature in some medium and to cool them at different speed after some time.

The metal heat treatment is one of the important crafts in the machine-building, comparing with other technologies, the heat treatment seldom changes the form of the work pieces and chemical composition of the whole .it improve the serviceability of the work piece through changing their micro- work pieces, chemical composition, or surface. Its characteristic is improving inherent quality of work pieces which can not be watched by our eyes.

In order to make the metal work piece have mechanics , physics and chemical property which are needed, besides the use of many materials and various kinds of crafts which are shaped , the heat treatment craft is essential. Steel is a wide-used material in the mechanical industry, its complicated micro-composition can be controlled through the heat treatment , so the heat treatment of the steel is a main content of the metal heat treatment . In addition aluminium, copper, magnesium, titanium and their alloys also can change their mechanics , physics and chemical property through the heat treatment to make different serviceability.

During the process of development from the Stone Age to the Bronze Age and to the Iron Age, the function of the heat treatment is gradually known by people. As early as 770 B.C.~222 B.C., the Chinese in production practices had already found the performance of the copper and iron changed by press and temperature . White mouthfuls of casting iron’s

gentle-treatment is a important craft to make farm implements.

In the sixth century B.C., the steel weapon was gradually adopted. In order to improve the hardness of the steel, quench craft was then developed rapidly. Two sword and one halberd found in YANXIA, Hebei of China , had “MA structure” in its micro-composition which was quenched.

With the development of quenching technology, people gradually found the influence of cold pharmaceutical on quality of quenching. Pu yuan a people of the Three Kingdoms(now, Shanxi province Xiegu town)made3000 knives for Zhu Ge-liang.the knives were quenched in Chengdu according to legend. This proved that the chinese had noticed the cooling ability of waters with different quality in ancient times, and the cooling ability of the oil and urine at the same time were found. People found a sword in Zhongshan tomb which were up to the Western Han Dynasty (B.C. 206 -A.D. 24 ),in whose heart department carbon was about 0.15-0.4%, but on whose surface carbon was about more than 0.6%.this has shown the use of the carburization craft. But as the secret of individual's " craftsmanship " at that time, the development was very slow.

In 1863, Britain metallo graphy expert and geologist's discoverity that six kinds of different metallography organizations existed in the steel under the microscope, proved that the inside of steel would change while heating and cooling. the looks of steel at the high temperature would change into a harder looks when urgently colded. Frenchmen Osmon established Allotropic theory , and Englishmen Austin first made the iron- carbon looks picture .these tow theories set the theoretical foundation for the modern heat treatment craft . Meanwhile, people also studied the metal protection in the heating to avoid the metal's oxidizing and out of carbon in