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1、Materials Section,R&D Center,FAW,ChinaShanqiang YingMay,22,2013,Research on the Application of Automotive Steels,2,Qualified/Stability,Silicon steel,Spring Steel,Bolting Steel,Gear steel,Rolled products,Non-quenched and tempered steel,3,3,M3,Compared with traditional material 16MnL,the new material
2、should be high strength to meet weight reduction,steel plates used as frames of the commercial vehicle,For example,with the yield strength of 500MPa grade can increase yield strength by 43%,making weight of the whole body frame decreased by about 300kg.Materials with the yield strength of 700MPa can
3、 make the weight reduction to achieve 23%.,4,Most of the hot-rolled steel sheets used as frames must be pickled to get rid of the oxide on the surface,but pickling process may make the surface rough and raise the cost of the process as well.It will be appreciated to have steel sheets to get rid of p
4、ickling.By improving the rolling process,a layer of Fe3O4 appears on the surface of the steel sheets.This kind of steel can perform well when being stamped,and the cost will be decreased as well.,This kind of so called“black surface steel”is being developed by many steel suppliers,including companie
5、s in Europe,Japan and China.Although Chinese suppliers have been making a lot of efforts,domestic steel products for car manufacturer are not as good as those by European and Japanese suppliers.,5,By comparison among Besturn B50 and some other foreign automotives,it can be seen that in FAW models,th
6、e use of the AHSS especially UHSS is still needed to be broadened.We are making our efforts on the application of AHSS and UHSS.In the model newly developed,PHS and the 3rd generation steel are utilized,and the scale of the application of AHSS and UHSS is increasing on our cars.,6,Hope for support f
7、rom steel suppliers,7,The spring steels are mainly used as suspension spring,valve spring,supporting spring for stabilizer bar and gearbox,etc.,Spring steels,8,Leaf springs are mainly used as a significant part in suspension of heavy-duty vehicles.Due to the need of lightweight,comfort and reliabili
8、ty,the working stress of the leaf springs increases a lot.As the tapered leaf springs are used more widely,the requirements for the spring steels are higher in good hardenability,high stress and long fatigue life,which is one new challenge for manufacturing of spring steels.For FAW,materials mainly
9、used contain 60Si2MnA,55CrMnA and 50CrVA.,Leaf spring of one Chinese truck,Furthermore,we also develop some other materials independently,such as 50CrMnSiVNb and 50CrMnMoVNb.,Spring steelsLeaf spring,Leaf spring of one Mercedes truck,9,With the development of heavy-duty vehicles,the load that the le
10、af spring born is increasing.The thickness of one leaf spring increases from 13mm to 24mm even to 50mm,so good hardenability is required.Accordingly,the FAW develops some new materials including 50CrMnVA and FAS3550,which makes a great contribution to the lightweight design.,Spring steelsthe applica
11、tion of leaf spring with good hardenablility,Harden ability,10,Spring steelsmaterials of leaf spring in FAW,11,Coil springs are used widely in cars and off-road vehicles,required with good fatigue performance and elastic extenuation resistance.So the materials are mainly Si-Cr series steel,usually h
12、eat formed.There are several kinds of materials mainly used as coil springs in FAW,such as 60Si2MnA,50CrVA,50CrMnVA,50CrMnSiVNb,50CrMnMoVNb,etc.As supporting spring for stabilizer bar and gearbox,materials are oil quenching and tempering spring wires:carbon steel wires and 55CrSi,etc.,(a)Coil spring
13、 used for off-road vehicles suspension;(b)Coil spring used for cars suspension;(c)Valve springs in engine.,Spring steelsCoil Spring,12,The valve springs bare high alternating load and high rotating speed,so it is required for the materials to possess good fatigue performance,good wear resistance and
14、 good heat resistance.The materials used in FAW are usually 55CrSi(oil quenching and tempering spring wires),most of which are produced by companies of Japan and Korea,while Chinese materials cant meet the demand of long fatigue life.Methods such as nitriding and shot blasting are being researched i
15、n the world to improve the design stress to a higher level.,Spring steelsmaterials of coil spring in FAW,13,Spring steelstorsion bar springs&stabilizer bar,The torsion bar springs for suspension are used in some light-duty vehicles，which mainly requires good fatigue performance.The torsion bar sprin
16、gs for over-turn device are used for turning over the cab or the trunk,which mainly requires good loose resistance performance and strongly pre-twist.There are two different kinds of materials with different heat treatment used as the torsion bar springs.One kind of material is carbon steel with ind
17、uction hardening,such as 45,40Cr.The other is spring steel with quenching and tempering,such as 60Si2MnA,50CrMnVA,50CrMnMoVNb,45CrNiMoVA,etc.,The stabilizer bar is an elastic part for keeping stable when cars are making a turn,usually with a complicated shape.There are two kinds of stabilizer bar,ho
18、llow and solid.The hollow stabilizer bar can decrease the weight for about 30%40%,which has been used in heavy-duty vehicles.Typical materials for hollow stabilizer bar include tubes made by 30CrMoA,35CrMoA,35Mn2,while common materials for solid stabilizer bar include 60Si2MnA,40CrMnVA,55CrMnA,55CrS
19、iA,etc.,14,The spring steel with high level of stress,fatigue resistance and elastic extenuation resistance are necessary for the automotive industry.Compared with other countries,the design stress of leaf spring and stabilizer bar is lower for 100200MPa.For example,the typical design stress of leaf
20、 spring we produce is usually 500600MPa,while in Europe and America,this value is 700800MPa.Similarly，the typical design stress for stabilizer bar is about 500MPa,while this value is 700MPa in Europe and America.Now the valve springs with high level of stress are usually produced by materials suppli
21、ed by foreign countries.In many other countries,the data of performance of fatigue and elastic extenuation of the materials and the CCT curve are all provided by the steel companies.For us,it is appreciated if we can get all these data we needed from domestic steel companies.,Spring steelsissues to
22、be solved by steel suppliers,15,Kinds of motors,automotive driving motors,Silicon steel,Silicon Steel,16,It is put forward by the National Outline for Medium and Long Term Science&Technology Development(20062020)that priorities will be assigned to research on and development of key technologies for
23、high-efficiency and low-emission internal combustion engines,fuel cell engines,accumulator batteries,driving motors,and other critical components,and technologies for developing experiment and test techniques and infrastructure for automobiles using new energy.As a magnetic permeability material,the
24、 silicon steel plays a significant role in the driving motors.It weighs more than half of the total weight of driving motor,and the cost of material is 40%of the total cost.The whole power of driving motors is determined by the electromagnetic properties of the silicon steel,and the reliability of d
25、riving motors is deeply affected by the mechanical properties of the silicon steel.,17,First,the frequency is way higher.In other industry,the frequency of the driving motor is usually 60120Hz,while in automotive industry,the frequency of the driving motor approaches to 1KHz.Second,the driving motor
26、 works under a high temperature for about 200 caused by the high frequency,which affects the properties of the materials.Last,good mechanical and fatigue properties are required due to high working frequency and high rotating speed(about 12000rpm).,2/3 of the whole silicon steels in the world are pr
27、oduced in China,while the best and advanced product is produced by the Nippon Steel in Japan.For recent years,China becomes the biggest supplier of the silicon steel.The key material of the driving motors used in automotive industry is different from those used in other industries.Unfortunately,ther
28、e is no standard of material and testing techniques for the material yet,which becomes an obstacle of the research and development of the driving motors for FAW and the whole industry.,Silicon steelthe characteristic of the automotive driving motors,18,Silicon steelMain impact factors of the magneti
29、c properties,Main factors affecting the magnetic properties of silicon steel,ThicknessFrequencyTemperatureProcess statusHeat treatment,19,The frequency of automotive driving motors keeps increasing,whick makes the core loss increases sharply.So the reduction of the thickness is the most efficient me
30、thod to reduce the core loss.With the decrease of thickness of steel sheets,the core loss goes down sharply.Compared with steel for the thickness of 0.35mm,the P10/P400 of the steel for the thickness of 0.30mm decreases for about 11%,while the P10/P400 of the steel for the thickness of 0.27mm decrea
31、ses for about 15%.So it will increase the efficiency of driving motors if the thickness goes down,which is also the trend of development of silicon steel.,Silicon steelthe trend of thinner sheet,20,Silicon steelthe development process,Manufacturing of driving motors,Application of silicon steel,21,F
32、AW has established some standards of the silicon steel and testing techniques,and keep researching on the development,application and testing techniques of the silicon steel.,Properties of typical silicon steels being used in FAW,Silicon steelmaterials used in FAW,22,1.The steel companies should dev
33、elop the silicon steel used in electric motors of high performance vehicle with high economical efficiency,reliability and friendly to the environment.2.We should develop the testing methods and the standards of the silicon steel with the characteristic of high temperature and frequency.3.We should
34、develop the testing methods and the standards of the mechanical properties for the design of the driving motors.4.It is expected that the steel companies can provide the key data for designing the electric motor of vehicles.,Silicon steelsissues to be solved,23,After the year of 2000,FAW made cooper
35、ation with the Northeast Special Steel Group and developed steel FAS2271 and FAS2237 for fracture-spilt connecting rod,steel FAS2225 for front axle,FAS2239 for crankshaft,and non-quenched and tempered steel FAS2241 with low cost.FAW also developed steel FAS2340 for front axle with Shi Jiazhuang stee
36、l company.,The non-quenched and tempered steelcurrent situation in FAW,24,The non-quenched and tempered steel,Hardness(HB),Impact value(J/cm2),Tensile Strength(MPa),High ductility,High strength,High strength&ductility(Martensite type),High strength&ductility(Bainite type),25,the non-quenched and tem
37、pered steel used in connecting rod,Connecting rod of MAZDA 6,26,Due to the demand of the reliability and low-noise of the engine,the accuracy of manufacturing of crankshaft must be improved.The shape and distribution of sulfide can affect the cutting performance of crankshaft,and the segregation of
38、sulfide may cause surface defect.In FAWs products,steel FAS2239 is utilized in the crankshafts of the 6DL series and DEUTZ series engine.,the non-quenched and tempered steel used in crankshaft,27,16Mn2VB 32SiMnVTiS FAS2225,Year 1986,45Mn2V Year 1992,12Mn2VB,16Mn2VB Now,32SiMnVTiS,FAS2225,the non-que
39、nched and tempered steel used in front axle,Through the results of the experiments,it is implied that the fatigue performance of the steel we use satisfies the requirements completely.,Front axle,28,Year 198440MnV NowadaysFAS2230,the non-quenched and tempered steel used in half shaft of automobiles,
40、29,FAW has made some experiments with the cooperation of Nippon Steel of Japan and Northeast Special Steel Group on the steel for grade 8.8 bolts,of which the main elements include manganese,chromium and niobium.Through the analysis of the microstructure,it is implied that there is hardly the tenden
41、cy to decarburization.Comparing the fatigue performance in high frequency with each other,we can see the difference.The fatigue limit of the one quenched and tempered is 496N/mm2,while the fatigue limit of the one non-quenched and tempered is 512N/mm2,which is better than the other.We keep developin
42、g and researching on the high strength non-quenched and tempered steel used for grade 10.9 bolts,of which the series of elements are low carbon-manganese-boron.,the non-quenched and tempered steel used in fastening bolts,30,the non-quenched and tempered steel used in fastening bolts,31,1.Since it is
43、 benefit to utilize the non-quenched and tempered steel,it is necessary for the automotive industries and the steel companies to keep developing and spreading the product.2.The non-quenched and tempered steel with high strength and high ductility should be developed.3.The improvement is necessary fo
44、r the standards of the non-quenched and tempered steel.4.The research should be kept doing for the non-quenched and tempered steel with low cost.,Suggestions for the steel suppliers,32,Nowadays,bolts are mainly used in automotive industry,electronic industry and architecture industry,among which aut
45、omotive industry is the biggest client,whose demand is 23.2%of all the sales volume.,In 2011,the volume of bolt production in China reached 6.8 million tons,with the sales revenue of 66 billion RMB.Thanks to the rapid development of automotive industry,architecture industry and manufacturing industr
46、y,the sales revenue of our bolting market may go to 200 billion RMB until 2015.,In 2011,the aggregate demand of the bolts in the global market is 64.4 billion dollars,and this quantity is increasing by 5.2%every year,which will reach 82.9 billion dollars in 2016.,The bolting steelcurrent situation,3
47、3,The volume of bolt production in China is about a quarter of the global production,40%of which is for exporting.China has become the biggest producer and exporting merchant.In 2011,the value of our export is 4.6 billion dollars,while the value of our import is 3 billion dollars.The average price f
48、or export is 1260 dollars per ton,while the average price for import is more than 9000 dollars per ton.,In 2008,the cold heading steels of high quality are used more than 1.8 million tons,which is 7%12%of all the steels of high quality in automotives.There are 14 tons of this kind of steels uesd in
49、FAW for one year.,According to some statistics,there are about 4000 bolts weighing 50kg in a car or a light-duty vehicle,while there are about 7500 bolts weighing 90kg in a medium-duty or heavy-duty vehicle,4/5 of which are high strength bolts.To one vehicle,the cost of bolts makes up 2.5%3%of the t
50、otal,and the number of bolts make up 40%of the number of all the parts.,The bolting steelcurrent situation,34,A large quantity of bolts used in FAW is provided by Jilin standard fastener company,and they do have some principles about the materials they use to produce high strength bolts.For example,
