【正文】 peak, the test force will be reduced, along with the decreasing crosssectional area of sample till the f racture. It can be seen that the appropriate toughness and plastic deformation proper ties of austenitizing sample at 900℃ will help HSS be hot formed to plicate vehicle parts. It is an effective measure to form HSS with roomtemperature martensite microstructure character, and it is a theoretical basis to design the hotforming process for HSS in the article.The vehicle hot forming parts and the original cold forming parts are practically contrasted. There areobvious differences both in the springback defect and in the formability, as shown in Fig5.From Fig5, it shows that the hotforming parts havehig her accuracy, almost no shape distortion, and no springback defect . But the coldforming parts will exhibit deformation defects, crimping,large spring back and twisted grooves obviously,which can destroy the yield of products seriouslyw hich can destroy the yield of products seriously .Therefore, instead of tradit ional cold forming , the vehiclehigh strength steels which are produced by hot forming have bee an inevitable trend. In addition, the positions of samples are shown inTable 1, based on not only the contribution for formability and microst ructure, but also the cost .For example, ponent boron as a ponent of sample can reduce the energygradient on the grain boundary because it is easily adsorbed on grain boundary to fill the defect of lower energy. Whileaustenitizing temperature is decreased by watercooling system, ?phase ferrite is easily to be nucleated on the grain boundaries. But the nucleation and growth of ferrite and bainite will bee slower because of the low erenergy gradient on the grain boundaries, and are beneficial to make austenite stable。 in addition, the plete closerow microstructure shows that residual stress ( including thermal stress and phase transformation stress, etc. )has been released pletely, and there is no microgap in the micrograins so as to benef it sample for higher security and better mechanical propert ies.T he domestic research of vehicle HSS is mostly limited to do in the lab, but advanced automated manufacturing technologies are difficult to be realized in the lab. In this paper ,the properties’ targets of HSS produced by practical production line are satisfactory, and the technical process also meets the demands of mass production(a) Original HSS microstructure before hot forming and quenching。熱成型工藝包括：快速加熱合金，奧氏體微觀結(jié)構(gòu)，沖壓和及時冷卻，保持壓力和淬火。關(guān)鍵詞：高強(qiáng)度鋼；重量輕；熱成型；馬氏體0 引言作為一種有效的經(jīng)濟(jì)的能源措施，輕巧的汽車發(fā)展方向，已成為汽車行業(yè)最重要的研究課題之一。在一般情況下，隨著鋼質(zhì)坯件的機(jī)械強(qiáng)度的增強(qiáng)，其可塑性急劇惡化。相對于原汽車珠光體鋼[2]，汽車HSS通過以下方式獲得先進(jìn)的熱壓成形技術(shù)可以減少車輛的總質(zhì)量的30％左右，實(shí)現(xiàn)復(fù)雜的幾何形狀，高安全性和機(jī)械強(qiáng)度。然后，樣品被壓在自制的水冷卻模具中冷卻，對于得到的HSS樣本，其形狀凍結(jié)字符或沒有回彈缺陷是一個明顯的優(yōu)點(diǎn)，并且大部分樣品中的顯微組織為馬氏體。2結(jié)果與討論硼鋼（HSS）的機(jī)械性能不同厚度（，分別）進(jìn)行了檢查（GBT168651997征求意見，樣本選取沿0℃，45℃和90℃軋制方向分別）。淬火前的強(qiáng)度的值的兩倍優(yōu)于那些樣本，（USIBOR1500在圖1所示）。從圖3，這是明顯的價值達(dá)到900兆帕，抗拉強(qiáng)度Rm在750℃的最優(yōu)值在900℃，為1530兆帕，當(dāng)溫度高于900℃，該值將下降。也就是說，樣品的拉伸強(qiáng)度是一個小較高她比原有的（Rm是600兆帕斯卡或左右）。然后，樣品是熱的形成和水冷卻的淬火，馬氏體組織樣品中的餾分是95％以上，所以該曲線示出了峰值。溫度/℃圖3拉伸強(qiáng)度與預(yù)熱溫度曲線至于樣品而言，A是初始的和未經(jīng)處理的樣品。B由與高溫的過渡奧氏體微觀結(jié)構(gòu)，其韌性也優(yōu)于馬氏體，和變形是大于后者。曲線的彈性變形階段中的值將趨于屈服點(diǎn)，之后逐漸增大的軸向試驗力。從圖4（b）中，相應(yīng)的峰值后，試驗力將降低，隨著樣品直到斷裂的減少的橫截面積。無論是在回彈缺陷和在成形性有明顯的差別，如在圖51所示。樣品的組合物如表1所示。在生產(chǎn)線中，混合相的析出和生長將有效地被禁止，通過控制溫度和加熱速率。其抗拉強(qiáng)度Rm和屈服強(qiáng)度分別只有653兆帕和500兆帕。在本文中，產(chǎn)生的HSS的屬性的目標(biāo)是令人滿意的，和實(shí)際生產(chǎn)線的技術(shù)工藝也符合大規(guī)模生產(chǎn)的要求。他們都將減少的拉伸強(qiáng)度。參考文獻(xiàn)：[ 1] Schieβl G, Pos schn T , Heller T , etal. Manufacturing a Roof Frame From Ultra High Strength Steel Materials by Hot Stamping [ C] IDDRG In ternational Deep Drawing Research Group 2004 Conference. Sindelfingen: [ s. n. ] , 2004: 158.[ 2] TANG Zhiyong, J IANG Haitao, TANG Di, etal. Study on the Continuous Cooling Transformati on of Austenite of 27MnC rB5 Steels [ J ] . Hot Working Technology, 2007, 36( 20) : 41.[ 3] FAN Junf eng, CHEN Ming. A Study on the Road of Vehicle Lightw eight in Chin a [ J] .Casting2006, 55( 10) : 995 ( in Chinese) .[ 4] CHEN Heqin g, PENG C hengyun, WEI Liangqing. High Strength Steels and Applicati on of Them to Vehicle Manufacturing [ J ] . Mould and Die Project, 2007 ( 8) : 88 ( in Chinese) .[ 5] LIN Jianping, WANG Liying, TIAN Haob in, etal. Research and Devel opment of the Hot Press Form ing of Ultra High Strength Steel [ J] . Metal Casting Forgin g Welding Technology, 2008, 37( 21) : 140 ( in Chinese) .[ 6] XING Zhongwen, BAO Jun, YANG Yuying, e