3A21铝合金的介绍

没有区别，3A21是新牌号，LF21是老牌号，是同一种材质。

LF21铝合金(新牌号3A21)为AL-Mn系合金，是应用最广的一种防锈铝，这种合金的强度不高（稍高于工业纯铝），不能热处理强化，故采用冷加工方法来提高它的力学性能：在退火状态有很高的塑性，在半冷作硬化时塑性尚好，冷作硬化时塑性低，耐腐蚀好，焊接性良好，可切削性能不良。用途主要用于要求高的可塑性和良好的焊接性，在液体或气体介质中工作的低载荷零件，如邮箱，汽油或润滑油导管，各种液体容器和其他用深拉制作的小负荷零件：线材用来做铆钉,广泛用于厨具、食物及化工产品处理与贮存装置、运输液体产品的槽、罐、以薄板加工的各种压力容器与管道、热交换器、铆钉、焊丝、洗衣机缸体等。

材料牌号: 3A21

标准：GB/T 3191-1998 铝及铝合挤压棒材材

国家与地区： China

金属类别： Aluminium Alloy

注释： Former Grade LF21, has the same chemical composition with present grade

中国的旧牌号LF21-新牌号3A21，那与3A21形似，将其替代的应该就是美国的3003（钎焊手册近似的认为是一种。没有严格的区别）.

具体成分比对结果：3A21与3003所含Si、Fe、Cu、Mn、Zn元素范围相同。3A21中较3003多含W（Mg）0.05、W（Ti）0.15

Vehicle Performance test system configuration and the diversity of the normative

Distributed networked control system. 3.3 System Performance System Performance Automotive comprehensive performance test that reflects the effect of output indicators, including the production of quantitative indicators - detection efficiency and quality indicators - both the content level of service. 3-3.1 detection efficiency. Detection system detection efficiency is reflected in the number of vehicles detected per unit time index, available on the number of vehicles seized, the number of annual inspection of vehicles, the effective annual number of vehicles and other indicators to represent. 3.3.2 services. Inspection station's output is essentially a service level of service reflects the detection system to detect the depth and breadth of the vehicle, the test results with the real situation close to the level of the index. 4 Conclusion According to incomplete statistics,mbt footwear, as of the late 90s, has been built around the country comprehensive performance vehicle inspection station 1500 (of which A-Station 338, B-class station 827, C-class station 335), a rational capacity \Communications Standardization \approach, in order to achieve the real effect of external relations. Key words: concreteappearance qualitycommon problemcontrol CLC: U443.17 Document code: B Article ID :1002-4786 (2004) 08-0036-02PreventionandCureExteriorQualityGeneralDiseaseofConcreteLIUFeng - yunHenanRoad-bridgeDevelopConstructionGeneralCompany, Shangqiu476000, China) Abstract: Inordertogetthearticleresulttheexteriorqualityofconcreteshouldadoptsomemea. suresofpreventionandcure. Keywords: concreteexteriorqualitygeneraldiseasepreventionandcure quality of concrete structures, including internal quality and appearance quality. Modern construction technology and management structure for the intrinsic quality of easy assurance, but the quality of the appearance of structures there is always this or that defect, the light can not be rated as excellent works, causing heavy scrap, in the economic, credit, causing significant losses. Therefore,tory burch shoes, the structure must attach great importance to visual quality, especially for large-scale bridges and overpasses and other cities, the appearance size and quality of utmost importance. ,>7,>7,>7,>7,>7,>70: ->, 0 :->,ralph lauren uk,,>7 a,http://www.wholesale-maccosmetics.org, the appearance of quality defects of concrete quality problems, including the appearance of concrete cellular, Ma surface, fracture, color, smoothness bad, cold joint aspects. (A) of the cellular concrete structures there, Pock 1. Causes ① concrete segregation. ② stone size larger. ⑧ vibration due to vibration or leakage. ④ poured concrete layer thickness does not meet the requirements. Support, management and orderly,mbt shoes discount, convenient and comprehensive performance testing of automotive network has been formed, the state of technology for the protection of the vehicle completely, the quality supervision and inspection of vehicle maintenance, improve road transport capacity to provide strong technical support and protection. Comprehensive performance test in China's automobile industry development, the test standards and regulations have been established and improved, standardized testing system from the general trend is increasing, but on the other hand, Vehicle Performance Test System Configuration 2. ① Select level solution with the thickness of cell aggregate, maximum aggregate size must meet the minimum bar spacing requirements. ② rate adjustment sand and concrete slump, meet workability requirements. ⑧ concrete vibrator vibration can not leak due to vibration, can not be too vibration. Tap the eligibility criteria for the concrete is no longer sinking, no bubbles can be. ④ concrete to meet the requirements of the mixing time and casting methods, when the infusion there was a high degree of convergence of ≥ 2m, the problem of inadequate personality, test system configuration from the testing requirements is more serious. Solution to this problem is, we must first full analysis of test demand, to meet the testing standards and testing requirements based on the purpose of testing the system structure and configuration to achieve the normative and unity in diversity, which is the rational allocation of inspection resources and improve the effectiveness of detection systems and means of the inevitable requirement. Received date :2004-04-12j \ More articles related to topics：

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铝基钎料铝硅系合金的熔点低，流动性好，适合作钎料。典型的铝基钎料是4343、4045(美国牌号)和4004合金。工业纯铝、铝锰系合金和铝-镁-硅系合金中的6951(美国牌号)合金有很好的钎焊性能，它们可用上述铝基钎料钎焊。铝镁硅系中的6061、6053(美国牌号)和6063合金也有较好的钎焊性能，但是因为它们的开始熔化温度比工业纯铝和铝锰系合金的低，因此要严格控制钎焊温度，以防止过烧。4004钎料含有镁，适合在真空钎焊法中使用，在钎焊过程中，镁的蒸气与炉内残留的氧和水反应，起净化作用，镁蒸气还抑制被钎焊铝合金的再氧化。

4343钎料适用于钎焊1060、 1100、3A21等铝合金母材，4043和4047钎料适用于钎焊3004、6063、6082等铝合金母材。