DP980+Z烘烤硬化值与退火温度的关系

摘要：为了研究退火温度对镀锌DP980+Z烘烤硬化值的影响，退火温度控制在760～820℃之间，系统分析退火温度对烘烤硬化值的影响。通过准静态拉伸试验机测量烘烤硬化值及抗拉强度，采用lepara试剂对组织中的马氏体进行着色，利用金相显微镜及图像处理软件测量马氏体的体积分数；采用扫描电镜观察DP980+Z的双相组织特点，并且将组织图片通过CAD转化成有限元图进行网格划分，建立代表性体积单元（RVE），通过有限元分析铁素体、马氏体强度对烘烤硬化值的影响。在同样的变形量情况下，DP980+Z的原始屈服强度越高，烘烤硬化值越高。     

Effect of Continuous Annealing on Microstructure and Bake Hardening Behavior of Low Carbon Steel

The influences of the heating rate,annealing temperature and soaking time during continuous annealing on the microstructure evolution and bake hardening behavior of the low carbon steel were investigated.After 2% prestraining,bake treatment(180 ℃×20 min)was carried out to measure BH(bake hardening)values.The results showed that,with the increase of the annealing temperature,the grain size increased except for annealing in the intercritical region.Furthermore,the BH value increased and the mean grain size reduced with increasing the heating rate from 5to 80 ℃/s.The BH value was very low before complete recrystallization.After a significant decrease from 630 to 720 ℃,the BH value enhanced when the steel was annealed at 750℃.With the increase of the soaking time from 20 to 100s,the BH value reduced linearly due to the segregation of solute C atoms.     

不同成分体系对超低碳烘烤硬化钢性能的影响

研究了不同成分体系超低碳烘烤硬化钢的性能特征,生产结果表明:Ti-BH钢屈服强度和BH值较低,伸长率和"值富裕量较大,并且BH值波动较大.通过对不同成分体系钢板的微合金化原理进行分析,确定了不同成分体系烘烤硬化钢性能不同的原因,并据此将烘烤硬化钢的成分体系由Ti-ULC改为Nb+Ti复合体系.更改后的烘烤硬化钢性能指标...     

Study of Bake Hardenability and Strengthening Mechanism of Hot Rolled Low Carbon Steel

The controlled rolling and controlled cooling,bake hardening experiments have been carried out for the test steel,mechanical property test of the sample and microstructure analysis have been made by tensile testing machine,optical microscope,TEM and X-ray diffractometer.The results show that fine and uniform microstructures can achieve much higher BH and BHT values;With the increase of pre-strain there is a trend of increase first and then decrease in the BH and BHT values;bake hardening mechanism mainly consists of Cottrell atmosphere strengthening,second phase strengthening,dislocation strengthening.     

Physicochemical and sensory characteristics of no‐bake wheat–soy snack bars

BACKGROUND: Health and wellness is a trend observed throughout ready‐to‐eat cereals, cereal health bars. Therefore, the main objectives of this research were to produce a low cost, acceptable, nutritious and healthy wheat‐ and soy‐based bar under no‐bake conditions. Also, the physical, chemical, microbial, acceptability and the nutritional value of this product were studied. Six different bars were produced: a wheat bar (WB), a wheat bar with coating (WBC), a wheat and soy bar with coating (WSBC), a soy bar with coating (SBC), a wheat bar with 3% glycerin (WB3%), and a wheat bar with 6% glycerine (WB6%). RESULTS: WB and WBC had the highest water activities while WSBC had the lowest. The three bars with coating had higher L and lower b values, which indicates that they were lighter and not as highly yellow coloured as the wheat samples. WSBC had the lowest value for hardness while the SBC and WBC had the highest. SBC received the highest scores for overall acceptability, appearance, sweetness, flavour and texture while WSBC received the second highest score in all categories. CONCLUSION: It appears that consumers prefer the soy varieties to the wheat bars. These types of bars can aid in feeding the general population, which is becoming increasingly concerned with nutrition and convenience. Copyright © 2010 Society of Chemical Industry     

Development of 600MPa High Aluminum Cold Rolled Dual Phase Steel and Its Application

An original 600MPa high aluminum dual phase steel had been successfully developed in this paper.The microstructure analysis showed that the microstructures of the steel mainly consist of ferrite and 16% martensite which distributed around the ferrite grain boundaries.TEM analysis demonstrated that there exist lots of high density dislocations in ferrite as well as an obvious twin-structure and some ribbon structures in martensite.The tensile test and the bake-hardening test showed that the steel delivers an excellent mechanical properties of R p0.2 =350-390MPa,R m =620-660MPa,R p0.2 /R m =0.55-0.65,A 80mm =25-29%,n=0.18-0.21 and an excellent bake-hardening property of BH 2 =50-60MPa as well as an excellent of work-hardening (WH) property of WH=120MPa。The spot-welding test showed that this dual phase steel has a good welding adaptability.Own to the excellent formability,the steel has been successfully used in the production of some auto parts.     

Effect of hook characteristics on the fracture behaviour of dissimilar friction stir welded aluminium alloy and mild steel sheets

ABSTRACT

Under tensile shear loading, fracture modes of dissimilar lap welds produced by friction stir scribe technology were studied. Three fracture modes were observed. For zone A fracture, the initial crack was restrained, and the joint ultimately fractured in the base mild steel. For zone B fracture, the initial crack progressed through the aluminium sheet just above the Al/steel interface. For zone C fracture, the initial crack proceeded along the steel hook to the aluminium sheet surface. Fracture mode and joint strength were greatly influenced by steel hook size, and the steel hook size was affected by welding parameters and tool scribe height. In this study, the experimental joint strength achieved the calculated joint load limit.     

Experimental study on Ti+Nb bearing ultra-low carbon bake hardening sheet steel hot-rolled in the ferrite region

A Ti+Nb bearing ultra-low carbon bake hardening sheet steel hot-rolled in the conventional austenite region and in the ferrite region with lubrication was experimentally studied.Subsequent cold rolling and continuous annealing processes were also conducted.The results show that microstructures of ultra-low carbon bake hardening hot strips at room temperature are basically irregular polygonal ferrites.The yield strength,ultimate tensile strength,n value,and r value of the No.2 specimen hot-rolled in the ferr...     

添加HPMC对无麸质大米面包品质的影响

水稻是全球主导的粮食作物之一,作为无麸质食品的主要原料倍受青睐。但水稻中缺乏面筋蛋白,在发酵过程中难以形成持气性较好的网孔结构,所以很难获得理想的面包类发酵产品。本论文探讨了采用HPMC为面筋替代物制作无麸质大米面包的可行性,并研究了HPMC对大米面包品质的影响,从而为无麸质大米面包的制作奠定基础,为大米资源的广泛应用开辟新的途径。结果表明,当添水量提高到100%110%时,4%的HPMC可以作为面筋替代物,用以改善大米面团的品质,烘焙出优质、理想的无麸质大米面包,但其淀粉体外消化率和整体感官评价却受到影响。最后认为,应该把无麸质大米面包看作为一类新型的焙烤食品,不一定要完全适用小麦面包的评价体系。