热处理过程中产生的过烧组织,在一定程度上会损害铝硅合金基体的连续性,直接影响合金的力学、耐疲劳、耐腐蚀等性能.过烧对铝硅合金基体的影响,在后续的机加工、涂装等过程都无法消除.因此,对过烧组织的判定是材料检测的重点.相比于行业标准JB/T 7946.2—1999《铸造铝合金金相铸造铝硅合金过烧》,JB/T 7946.2—2017《铸造铝合金金相第2部分:铸造铝硅合金过烧》,完善了标准适用范围,增加了规范性引用文件,修改了过烧、过烧三角、复熔球、复熔共晶体等术语和定义,补充了试样的切取和制备工艺,完善了部分过烧级别的金相组织,更新了原有效果较差的金相组织图.本文有助于JB/T 7946.2—2017标准的宣贯和使用者对标准的理解.%The burned structure generated from heat treatment will damage the continuity of aluminum-silicon alloy substrate partly, which affects mechanical properties, fatigue resistance, corrosion resistance and other properties directly. This effect can not be eliminated in subsequent machining and coating processes. Therefore, the determination of burned structure is important for material testing. Compared with JB/T 7946.2—1999 edition, JB/T 7946.2—2017 "metallograph of cast aluminum alloys -part 2: cast aluminum-silicon alloys burning", the scope of standard application is changed, normative reference files is added, terms and definitions such as burning, burning trigonum, remelting pellet and remelting eutectic are revised;supplemented sample cut and preparation process;completed the microstructure of some burned levels;updated metallographic pictures with poor effect on original ones. This article will avail JB/T 7946.2—2017 of being implemented and comprehensive.
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