浅析冷轧辊的失效与维护

就宝钢冷轧薄板厂冷轧辊的使用状态介绍了冷轧辊的损耗类型,着重分析了冷轧辊产生剥落甚至爆辊的原因,同时提出了预防措施.     

冷轧板边裂原因分析及预防

从热轧原板材料缺陷性能、冷轧工艺等方面分析了冷轧板边裂产生的原因.认为冷轧轧机负荷分配和机架间张力控制不当是边裂产生的主要原因,热轧板边部混晶和硬度波动对其边裂有一定影响.优化冷轧工艺,有效控制热轧板组织均匀性,是解决边裂的主要措施.     

5A06铝合金薄壁管材冷轧裂口成因与工艺措施研究

针对5A06合金薄壁管材在冷轧过程中产生裂口缺陷这一棘手问题,从挤压管坯料质量、管坯退火制度以及送料量等方面分析其产生原因,探讨防止或消除冷轧过程中产生裂口缺陷的方法.     

汽车油底壳冲压失效原因分析

采用网格分析技术对St14ZF冷轧钢板冲压汽车油底壳产生颈缩、裂纹的原因进行了分析,评估了St14ZF冷轧钢板冲制油底壳的成形效果,指出油底壳产生颈缩、裂纹主要是由于St14ZF的安全裕度偏小,应选取FLD0大于50%的冷轧钢板冲压油底壳.     

新型冷轧实验轧机的工艺设计

根据当前冷轧实验轧机的概况分析,并结合冷轧实验对设备的特殊要求, 设计开发了两侧通过液压缸和夹头产生张力的新型直拉式可逆冷轧实验轧机.介绍了该轧机的主要工艺设备参数和系统配置.确定了实验工艺流程,并根据该实验轧机的设备布置设计了轧制工艺.该新型冷轧实验轧机已经成功投入使用.     

双辊铸轧704不锈钢薄带的冷轧实验

对双辊铸轧704不锈钢薄带进行了冷轧处理,分析了冷轧前后薄带的表面质量及显微组织.结果表明:在冷轧过程中,因动态再结晶和动态回复,使薄带的晶粒进一步得到细化.变形量过大时,冷轧薄带内部出现微观晶界裂纹,并随着变形量的增加最终发展成宏观裂纹.笔者还应用金属学、结晶热力学对晶界裂纹的产生机理进行了分析,认为当冷轧变形量达到一定程度后必须对薄带进行固溶处理,以避免裂纹出现.另外,结合冷轧过程中薄带板形的变化,对704不锈钢铸轧薄带给出了合理的冷轧变形量.     

高牌号无取向硅钢稳定轧制研究

影响高牌号无取向硅钢冷轧生产稳定性的主要因素是轧后边裂造成断带。造成冷轧后边裂的因素很多,主要研究常化工艺、切边质量及冷轧工艺对边裂产生的影响。针对性采取措施进行工艺优化,冷轧后边裂产生率大幅下降。     

冷轧产品边裂成因分析及控制

鉴于冷轧边裂情况比较复杂,主要从热轧温度制度、冷轧酸洗切边和冷轧负荷分配等方面进行了分析。结果表明：冷轧边裂产生的原因是热轧温度制度不稳定、冷轧酸洗切边不良以及冷轧轧制负荷分配不均。通过采取相应的预防、控制措施,取得了较好的效果。     

冷轧铜板带残余应力成因及消除方法浅析

文章从冷轧铜合金板带残余应力的产生原因及消除方法等方面,综述了铜合金板带残余应力研究现状;指出深入了解冷轧铜合金板带残余应力的产生原因,研究高精度铜带箔残余应力的控制及消除工艺方法并在生产中产业化应用已经刻不容缓.     

冷轧带钢退火粘结缺陷原因分析及控制措施

针对冷轧带钢罩式退火后产生粘结而降低成材率的问题,分析了冷轧带钢罩式退火后产生粘结的原因,通过采取优化轧机成品卷取张力、提高末架轧机工作辊粗糙度、优化退火及平整工艺等措施,有效降低了冷轧带钢的退火粘结缺陷率。     

Stress corrosion cracking of α-brass in waters with and without additions

Slow strain rate stress corrosion tests on a 0.032 pct As brass in SO₂ solutions of increasing dilution eventually resulted in tests being carried out in various waters which were also found to promote cracking. A 0.002 pet As brass was also found to be susceptible to cracking in deionized water, but in brackish water or an acidified sulfate solution this brass did not display the stress corrosion cracking observed in these more aggressive solutions by the higher As brass. The addition of arsenite to distilled water or arsenate to deionized water in sufficient amounts effectively inhibited the cracking observed at controlled potentials or open circuit in these waters without the As additions. The results are interpreted as indicative of dezincification being involved in these various environments that promoted cracking, but the extent of the dezincification plays an important role in determining whether or not cracking occurs, those additions leading to rapid and massive dezincification involving redeposition of dissolved Cu not being conducive to cracking.     

Stress corrosion cracking of alpha brass in a tarnishing ammoniacal environment: Fractography and chemical analysis

Alloy 260 brass specimens under stress were exposed at room temperature to 15 N aqueous ammonia solution with 8 g/1 of cupric copper predissolved. This environment causes tarnishing of the brass surface and intergranular stress corrosion cracking. Scanning electron microscopy, energy dispersive X-ray analysis, and Auger electron spectroscopy were employed to study fractography, corrosion product composition and distribution within the stress corrosion crack, and fracture surface chemistry characteristic of stress corrosion cracking in this system. A thin oxidized film was detected by Auger spectroscopy at the leading edge of the propagating crack. With continued exposure to the corrosive environment, deposits form on the fracture surface, then coalesce to form a continuous tarnish film that is depleted of zinc. No bulk depletion of zinc was detected in the alloy at the stress corrosion crack leading edge. No evidence of noncrystallographic crack arrest marks was found on the intergranular fracture surface.     

The SCC of single crystals of β brass in water: Fractography and crystallography

The crystallography of transgranular stress corrosion cracking (TG-SCC) in randomly oriented β brass single crystals exposed to distilled water has been studied over a range of electrochemical potentials and slow strain rates. Transgranular SCC in this system is characterized by unusually large {001} crystallographic facets. Steps linking these primary {001} facets were also observed to be of the {001} orientation. Additionally, it is observed that cracking prefers to follow the <011> directions. W.K. BLANCHARD, Jr., formerly Graduate Student, Department of Metallurgical Engineering, Michigan Technological University,     

The influence of deformation path on the slow strain-rate stress corrosion cracking of admiralty brass sheet

The slow strain-rate stress corrosion cracking (SCC) of Admiralty brass sheet in an aqueous 0.1M CuSO₄ solution has been studied over a range of strain paths from uniaxial to equibiaxial tension. At a constant bulk solution pH and open circuit potential, the brass undergoes transgranular SCC characterized by cleavage-like cracks propagating on a macroscopic plane normal to the maximum principal strain axis for all strain paths. The average crack growth velocity is also independent of deformation path. It is thus concluded that the mechanism of transgranular SCC in this system does not depend on multiaxial strain path for the range of stress states examined. However, the fracture strain data show that the slow strain-rate SCC of the brass sheet results in ductility losses which are much larger in equibiaxial tension than in either uniaxial or plane strain tension. This behavior is attributed to stress corrosion cracks acting as linear imperfections whose presence causes failure of the uncracked ligament by a form of localized necking and whose influence is dependent not only on time but also on strain path.     

Stress corrosion cracking relation with dezincification layer-induced stress

Brass foil with a protective layer formed on one side was deflected during corrosion in an ammonia solution under various applied potentials, and then corrosion-induced stress generated at brass/dezincification layer under different potentials could be measured. At the same time, susceptibility to stress corrosion cracking (SCC) of brass in the ammonia solution under various applied potentials was measured by using a single-edge notched specimen. At open-circuit potential, both corrosion-induced tensile stress and susceptibility to SCC (I _σ) had a maximum value. Both tensile stress σ _p and susceptibility I _σ decreased slightly with decreasing potential under anodic polarization, but reduced steeply with a decrease in potential under cathodic polarization. At the cathodic potential of − 500 mV_SCE, corrosioninduced stress became compressive because of the copper-plating layer; correspondingly, susceptibility to SCC was zero. Therefore, the variation of SCC susceptibility with potential is consistent with that of the corrosion-induced additive stress.     

无铅易切削黄铜的现状及改进方向

概述了目前国内无铅易切削黄铜的应用状况,重点介绍了无铅易切削硅铋黄铜的开发及应用,该系合金既有硅黄铜、铋黄铜的优点,又克服了其缺点,并具有良好的性价比,应用前景良好。     

High temperature creep of ordered and disordered beta brass—I. Creep rate

The high temperature creep behavior and creep transient behavior after strain transient dip tests were investigated in ordered and disordered beta brass solid solution alloys. No primary creep is observed in ordered beta brass. A brief inverted primary creep is observed in disordered beta brass. The power law creep exponent for steady state creep is 3.5 in ordered beta brass and 3.2 in disordered beta brass. The instantaneous elongation and the instantaneous contraction for a given stress change are in good agreement in ordered and disordered beta brass. The dislocations observed in ordered beta brass show smoothly curved shapes with homogeneous distributions.     

无铅易切削黄铜的研究进展(续)

2我国已授权或已公开的无铅易切削黄铜专利 唐吉苗等发明了一种含硅无铅易切削黄铜^[23]。合金成分的质量分数分别为铜80％-84％,硅2．5％-5．0％,砷0．02％～0．10％,杂质总量不大于0．05％,余量为锌。该合金具有良好的切削性能、力学性能和导电性能。     

加工工艺对稀土HSn62-1黄铜耐脱锌腐蚀性能的影响

采用脱锌腐蚀深度测量方法、恒电位测试方法和光学显微镜等分析方法,研究了不同的加工工艺对稀土HSn62—1黄铜的耐税锌腐蚀性能的影响。结果表明,冷轧态的黄铜,由于β相沿着冷加工方向分布,同时位错密度和残余应力的增加,导致了其耐脱锌腐蚀性能比热轧态的黄铜和铸造态的黄铜差。热轧态的黄铜,由于在热加工过程中发生了回复和再结晶,使得其耐蚀性和铸造态的相当。     

无铅易切削黄铜的特点与发展方向

综述了我国无铅易切削黄铜合金的研究、开发和使用现状,重点介绍了目前广泛生产和使用的铋黄铜、硅黄铜的主要特点;分析了一种新型无铅易切削碲铋黄铜的开发使用情况,认为该系合金拥有具有硅黄铜、铋黄铜的优点,同时克服了相应的缺点,具有一定的应用发展前景;分析了我国无铅易切削黄铜合金的发展方向是高性能、易成型、低成本及系列化。