【正文】 ite steel[ 2] , the automobile HSS obtained by advanced hot press forming technique can reduce about 30% of the total vehicle mass and achieve plex g eomet ries, high security and mechanical st reng th. The r easo n is that austenite microst ructure with optimal plast icity and ductility can be obtained by hot press forming at high temperature[ 3 5] , and the HSS with both excellent mechanical properties and light weight will be obtainedafter being formed and quenched[ 6 8] . The application of hotformed thinner HSS plates will bean important measure to realize vehicle light weight.1 Experimental SetupIn order to form HSS at high temperature, and to avoid cracks and springback, the sam ples need rapid heating and transform pletely into stabl eaustenite microst ructure. And then, samples are pressed and cooled in selfmade watercooling the obtained HS S sample, its shapefreezing character or no spring back defect is an obvious advantage, and most of microst ructure in the sample is martensite. The thickness of sample is mm, and the main elements of HSS in this experiment are show n in Table 1.Table 1 Main elements of material in the experimen22MnB5CMnCrSiBPSAlMinimumMaximumActual ex perimental procedure included: 1) set different heat t reatment temper atures in ther ange of750 to 1 000℃。 martensiteAs an effective economical energy measure, the lightw eight dev elo pment dir ection of automo bile has bee one of the most important research subjects in the automotive industry. There are three major ways to achieve automobile light weight : optimizing vehicle frames and struc tures。 lightw eight 。 專業(yè)資料分享 Influence of Hot Press Forming Techniques on Properties of Vehicle High Strength Steels( Scho ol of Automotive Engineering , State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian University of Technology , Dalian 116024, Liaoning, China)Abstract: Based on the bination of materials science and mechanicalengineering ,hotpress forming process of the vehicle high strength steels was analyzed. The hot forming processinclud ed: heating alloy srapidly to austenite micr ostructures, stamping and cooling timely,maintaining pressur eand quenching . The results showed that most of austenite micr ostructure w as changed into uniform mar tensite by the hot press form ing while the samples were heatedat 900 。C and quenched. The optimal tensile strength and yield streng th were up to 1530 MPa and 1000 MPa, respectively, and the shape deformation reached about 23% . And springback defect did not happ en in the samples.Key words: high streng th steel。 hot forming 。 making vehicle bodyor 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) 。 2) put the sample into the heat treated furnace to be heated for 4 min at a certain temperature。4) simultaneously, it was watercooled at about 30℃/s in the mound. The mechanical properties of sample were analyzed by tensile test system and the microstructure appear ance was analyzed by metal lographic analysis device.The shape and size of test sample are show n in Fig. 1.Fig 1 The shape and size of specimen2 Results and DiscussionMechanical propert ies of HSS ( boron steels)with different thicknesses ( , , , mm, mm and mm, respectively) were checked (GBT 168651997 was consulted, and samples were selected along 0℃, 45℃ and 90℃ rolling direction respec tively ) . The unidirectional tensile tests (based on the metal tensile test ing standard of GBT2282002 ) were finished. Compared with USIBOR1500, the values of basic mechanical properties for HSS w ith dif ferent thicknesses in the experiment are shown in Fig 2. Fig 2 shows that after watercooling quenching , the tensile strength and yield strength of samples ( except the one w ith thickness of mm )reached 1 500 MPa and 1 000 MPa, respect ively. The values of the strength were twice bet ter than those of samples before quenching , and nearly the same to those of the plates of thickness mm from Acelor Company ( USIBOR1500 shown in Fig 1) .Fig2 Tensile and yield strength of high strength steels with different thicknesses before and aft