With the development of the industry of automobile, machine, construction and light industry, it requires higher and higher quality of various kind of fastening pieces.

It needs to raise the requirement of design stress and light weight for bolt because of the high capability and light-weighting of automobile, the high-raise of building and super long bridge. Therefore, the bolting steel must be improved as much as it can. In USA, the degree of the bolts used for automobile is above 9.8 and the intension of some automobile and construction machine bolts even require to be more than 1400M Pa. The full length of the magnetic suspension project in Shanghai, which is the key project in China, is 30 kilometers and it needs 1.5 million sets of high-intentioned bolts that is to be used for tightening the stator core of magnetic suspension and tightening the joint of crossbeam and it must assure that they won't rust within 40 years and it has special standard for the intension.

It is reported that the R & D of high-intentioned bolts of 1500M Pa has been a key project in China to meet the demand of fastening pieces in Chinese market.