[实用参考]机械类英语论文翻译.doc

Influence of Hot Press Forming Techniques on Properties of

Vehicle High Strength Steels

( Scho ol of Automotive Engineering , State KeP LaboratorP of Structural AnalPsis for Industrial Equipment,

Dalian UniversitP of TechnologP , Dalian 116024, Liaoning, China)

Abstract:Based on the combination of materials science and mechanicalengineering ,hotpress forming process of the vehicle high strength steels was analPzed. The hot forming processinclud -ed: heating alloP srapidlP to austenite micr ostructures, stamping and cooling timelP,maintaining pressur eand quenching . The results showed that most of austenite micr ostructure w as changed into uniform mar tensite bP the hot press form ing while the samples were heatedat 900 。C and quenched. The optimal tensile strength and Pield streng th were up to 1530 MPa and 1000 MPa, respectivelP, and the shape deformation reached about 23% . And springback defect did not happ -en in the samples. KeP words: high streng th steel; lightw eight ; hot forming ; martensite

As an effective economical energP measure, the lightw eight dev elo pment dir ection of automo -bile has become one of the most important research subjects in the automotive industrP. There are three major waPs to achieve automobile light weight : optimizing vehicle frames and struc- tures; making vehicle bodPor f rame of new and alternativ ematerials to reduce the vehicle mass ( The high and ultra high strength steel can be used as alternative materials because of its thinner thickness) ; adopting advanced manufacturing techniques for the sake of automobile light wei- ght , such as thickness-gradient high strength steel (HSS) or metal based compound plates bP con -tinuous pressing or hot press forming [ 1] . Although HSS has been applied in some domestic top grade vehicles, the keP producing technologies have alwaPs been dominated bP foreign compan- ies, such as Acelor CompanP, so as to raise the product cost obviouslP. BP domestic self-designed hot press forming techniques and water-cooling mould, the automo bile HSS can be produced to subst itute foreign vehicle parts.

In general, with the enhancement of steel blank，s mechanical strength, its formabilitP is worsened dramaticallP. It is difficult to applP the traditional cold stamping technolog P into the f ield of pressing HSS. Thus, the hot stamping technologP of martensit icsteel blank is applied as a new technologP , which combines metal thermoplast ic forming metho d and water-cooling mould quenching principle. In this paper, boro n steel blank was formed and water-cooling mould was quenched simultane ouslP during the process of hot stamping . Compared

with original automobile pearlite steel[ 2] , the automobile HSS obtained bP advanced hot press forming technique can reduce about 30% of the total vehicle mass and achieve compleP g eomet ries, high securitP and mechanical st reng th. The r easo n is that austenite microst ructure with optimal plast icitP and ductilitP can be obtained bP hot press forming at high temperature[ 3- 5] , and the HSS with both ePcellent mechanical properties and light weight will be obtained

after being formed and quenched[ 6- 8] . The application of hot-formed thinner HSS plates will becoman important measure to realize vehicle light weight.

1 EPperimental Setup

In order to form HSS at high temperature, and to avoid cracks and springback, the