Research progresses of forming causes for orange peel during the tensile deformation of aluminum alloy sheet are reviewed. This paper first shows the surface morphology of tensile deformation of sheets with orange peel and non orange peel，sliding zone，roughness of surface，tensile fracture morphology and nano hardness measurement results and characterization. Recent research results of electron backscattered diffraction（EBSD）using the forming causes of orange peel and the texture measurement results of orange peel and non orange peel using X-ray are further introduced. According to the mentioned results，microstructure and mechanical properties，the forming causes of orange peel are analyzed further. A series of results show the appearance of orange peel surface after tensile deformation is closely related to the texture and grain orientation caused in tensile deformation. The texture generating is closely related to inhomogeneity deformation of grain. Grain size will significantly affect the inhomogeneity deformation and the formation of texture ； coarse grain is easier to cause inhomogeneity deformation，grain rotation and texture than that of fine grain，resulting in surface orange peel forming after tensile deformation. Thus，it introduces a model of surface state of the coarse grain and fine grain after the tensile deformation. It is also suggested that the formation of orange peel should be further researched and analyzed so as to perfect the quantitative description of orange peel formation.
First，the process characteristics of aluminium alloy automotive sheet pre-treatment and the working principle of the air cushion furnace were introduced. The process location and irreplaceable role of air cushion furnace in the aluminium alloy automotive sheet production was pointed out after the difficulty and key point in the whole production process of the automotive sheet were studied. Then development process of air cushion furnace line of aluminum alloy sheet was reviewed ，summarized and divided to two stages. Based on the research status of the air cushion furnace，the key technology of it was analysed，and research key points on process， equipment and control models of air cushion furnace for aluminium alloy automotive sheet in future were put forward. As the rapid develop of the automotive industry，it will be certainly come that the new upsurge of the research and application of air cushion furnace for pretreatment of aluminum alloy automotive sheet.
To achieve satisfied automobile development that integrates various functionalities such as crashworthiness，passengers’comfort，structure reliability and cost control etc.，it is necessary to fully utilize computer aided engineering（CAE）analytical technologies with crossdisciplinary and multi-purpose approach，while taking account of comprehensive performance objectives and automobile development efficiency during the entire process of automobile new product development. Based on research and development process of Geely automobile，the parametric flex technology and multisystem optimization method are introduced to perform prediction and optimization in automobile crash，noise vibration harshness（NVH）and structure strength etc. so as to ensure automobile overall performance and design efficiency，and realize high-efficient development of Geely self-owned brand models eventually.
The present progress and applications in research on high manganese twinning induced plasticity and transformation induced plasticity（TWIP/TRIP）steel were summarized. The influence of grain size on TWIP effect was investigated. The evolution of grain size was investigated，which the mechanism of deformation twin evolution was analyzed. The deformation mechanism of deformation induced martensite and deformation twin was investigated. The effect of vanadium carbid（VC）precipitates on the delayed crack and strain hardening behavior was investigated， and the interaction between VC precipitates and deformation twin was discussed. The post-treatment technology，microstructure，mechanical properties and deformation mechanism of high manganese TWIP/TRIP steel fabricated by using twin-roll strip casting were investigated.
The low silicon transformation induced plasticity（TRIP）steel with phosphorus addition at every stage of fast annealing process has been studied by heat treatment experiment at lab. The effects of annealing temperatures on microstructure constitute at every stage are mainly studied. The addition of low price element phosphorus can reduce silicon content， improve surface quality，solve galvanizing problem and reduce costs. Results show that the ferrite content decrease，and the mixture of bainite and martensite content increase at final microstructure. By X-ray diffraction（XRD）analysis，the retained austenite content increases from 12.7 % at 750 ℃ annealing to 14.9 % at 790 ℃.
The mechanical properties， microstructures， fatigue properties and fatigue fractures of the conventional C-Mn wheel steels and the low- carbon low- silicon phosphorus/chromium-contained transformation induced plasticity（TRIP）steel were investigated. Results revealed that the new-type TRIP steel possessed similar yield strength ， tensile strength increased by 100~150 MPa and fatigue limit increased by 50~140 MPa，compared with the conventional C-Mn wheel steels. The fatigue limit increased with the increase of the tensile strength. The steel containing ferrite，bainite and retained austenite had a higher fatigue limit than the steel containing ferrite，bainite and pearlite or steel containing ferrite，pearlite and martensite-austenite islands.
In order to satisfy the requirements of lightweight in the automotive industry，the development of advanced high strength steel obtained using the quenching and partitioning （Q&P）process has been paid extensive attentions. In the present work，the application of Q&P concept during hot rolling was investigated for wide use of Q&P process on the conventional hot rolling production line. It was shown that introducing thermo-mechanical treatment during the conventional Q&P process was favorable for significantly refining the microstructure and obtaining a certain amount of retained austenite，and the experimental steel possessed the higher product of strength and ductility under the condition of maintaining higher strength. The feasibility of producing the hot rolled Q&P steel（DQ（direct quenching）&P steel）was determined on the hot rolling production line by employing the new-generation thermo mechanical control process （TMCP）with ultra fast cooling at the core.
For three different strength level， different thicknesses were systematically formability test，Comprehensive analysis of the mechanical properties of （dual- phase）DP steel，cupping performance，cold bending，forming limit. Studies show that：Elongation and the value of n for DP steel decreases with rising intensity level. Cupping test results show that the height of the cupping with the DP steels up strength level decreases，and increases with increasing thickness of the material. Duplex steel cold bending properties with increased material strength level decreases. Bulging under biaxial strain tests showed that DP steel has good formability. Based on mild steel FLD0 empirical formula can’t be directly applied to the DP steel.
Based on the 22MnB5's composition，new boron steel applied on hot stamping was developed by adding some special chemical elements，such as adding Cr，Mo. Materials properties， materials continuous cooling transformation curves（CCT） and heat- treatment properties of new boron steel were tested by metallographic microscope、micro- hardness and electronic tensile testing machines. Process parameters testing，parts production and part properties analysis were also finished by the middle production line and some other testing equipments. Tests result show that the new boron steel owned great oxidation resistance properties and fine microstructure，the new boron steel and 22MnB5 materials have the same strength levels，but new boron steel have better elongation than 22MnB5.
Based on the front bumper of a commercial vehicle，the hot stamping mould was developed，and the hot stamping experiment was carried out. The laser scanning，microstructure， microhardness and mechanical properties of the components were detected. The results showed that the shape of the components meets the design requirements；the structure of components after hot stamping is martensite structure；the hardness of the components is more than HV400； the yield strength of the components is more than 1 000 MPa；the tensile strength of the components is more than 1 400 MPa；the elongation exceeds 10 %.
Quenching and partitioning（Q&P）treatment was applied to cold rolling sheets of 409L and 410S ferritic stainless steels，which resulted in a multiphase microstructure of ferrite， martensite and retained austenite. The austenitizing temperature，quenching temperature and partitioning time were optimized to obtain the maximum martensite and retained austenite. Compared to normally annealed and quenching and tempering（Q&T）treated sheets，the Q&P treated one exhibited the best combination of strength and elongation，a continuous yielding and moderate n- value and r- value，which satisfied the requests of high strength and well formability and can substitute advanced high- strength steel in manufacture of automobile structural parts.
The present study focuses on the Ti-V microalloying system which draws less attention. By using the Formaster-FII dilatometer，the sample was held at austenite/ferrite dual- phase temperature region and the Ti-V complex interphase precipitates were obtained during the austenite to ferrite transformation. Optical Microscopy （OM） and transmission electron microscopy （TEM） were employed to analyze the microstructure，especially the morphology of the interphase precipitate and its crystallographic orientation relationship with ferrite matrix. Studies show that 650 ℃ is the nose temperature for static isothermal transformation. The interphase precipitates exhibit sheet-like distribution，including flat and curved sheets and adopt Baker-Nutting orientation relationships with the ferrite matrix.
This paper researched and exploited high strength hot rolling bulletproof steel B900FD. The chemical composition of B900FD was designed. The effects of different coiling temperatures on microstructure and mechanical property of bulletproof steel are discussed. The shooting test was carried out. The deformation characteristics and microstructure of the tested samples were analyzed. Cold forming and welding test were also progressed. The results show that B900FD has excellent strength and ductility compatibility. Shooting resistance property can satisfy the requirement of bulletproof steel. The machining and welding property can suit existing production process and reduce the cost. The comprehensive properties of developed B900FD steel achieve the standard of Protection specification for cash carrying vehicles (GA 164—2005).
The light-aging test method commonly used in the automobile industry is utilized to carry out light- aging research on automotive instrument panel（IP）materials and bumper materials. On one hand，the impacts of common light-aging test methods on aging degree of automotive component materials are compared；on the other hand，the light-aging resistances of different component materials are compared. The results show that，for light-aging behavior of IP materials，the aging degree of the third test method is not severer than that of the second method，but it is severer than that of the first method. The light-aging resistance of IP material A is almost the same as that of IP material B. With reference to light-aging behavior of bumper materials，the aging degree of three common test methods indicates that the aging degree of the sixth test method is not severer than that of the fourth method，but it is severer than that of the fifth method. The light- aging resistance of bumper material D is superior to that of bumper material C.
Research on heat treatment process of 6016 aluminum alloy has been carried out by means of hardness measurement，mechanical properties test and bake- hardening property test. The results indicate that hardness of alloy increases with the rise of solution temperature and solution time increase. The hardness of alloy initially decreases and then increases with pre- aging time increase when pre- aging. The higher the temperature of pre- aging，the bigger the decrease value of hardness will be. The heat treatment process of 6016 alloy satisfying the demand of outer panel property is：540 ℃×20 min solution treatment + 120 ℃×10 min preaging.
Researches on dent resistance property and the relationship among dent resistance， mechanical property and bake- hardening property of 6016 aluminum alloy have been carried out by means of mechanical properties test，bake- hardening property test and dent resistance test. The results indicate that after two years natural aging，the strain hardening exponent nvalue and elongation of 6016 aluminum alloy sheets increase. With 30 min baking at different temperatures，strength of the sheets increases. The bake-hardening values remarkably increase with temperature rising. The sheets exhibit good bake-hardening property. The dent resistance property is related to baking process. The higher the baking temperature is which leads to higher strength，the better the dent resistance property of the sheets will be.