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原文
Cast steel valve defect treatment 1, to determine defects In production practice, some do not allow welding casting defects, such as cross-cutting cracks, penetrating defect (hole in the bottom), honeycomb pores, slag sand can not be removed and area of ??more than 65cm2 of shrinkage, as well as both the contract not in agreement with other major welding defects. Before welding defects in the type of judge. 2, defects removed General can be used in the factory carbon arc gouging blow casting defects, and then polished with a hand-held angle grinder to reveal defects in parts of the metallic luster. However, production practice more directly with the carbon electrode to remove defects in high-current, angle grinder and grind with a metallic luster. General casting defects removed, can be <4mm-J422 electrode, 160 ~ 180A current, the defects in addition to a clean, grinder will be polished into a U-shaped mouth defects, reduce welding stresses. Remove defects complete, good quality welding. 3, defective parts warm Carbon steel and austenitic stainless steel castings, where the welding parts of the area <65cm2, depth <20% of the casting thickness or 25mm, generally without preheating. But ZG15Cr1Mo1V, ZGCr5Mo other pearlite steel castings, steel hardening tendencies as big, cold welding easy to crack, should be preheating, preheating temperature of 200 ~ 400 ℃ (with stainless steel electrode welding, the temperature take a small value), insulation time should be less than 60min. If the casting is not the whole warm-up, available oxygen - acetylene and extends 20mm in the defect site after heated to 300-350 ℃ (visual observation of dim red back in the dark), large torch flame gun first in the neutral defects and do around fast swing circle a few minutes, then slowly move to maintain a 10min (depending on the thickness of the defect), so that defective parts fully warmed up, quickly repair welding.
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译文：
1、缺陷判断在生产实践中,有些铸件缺陷不允许补焊,如贯穿性裂纹、穿透性缺陷(穿底)、蜂窝状气孔、无法清除的夹砂夹渣和面积超过65cm2的缩松等,以及双方合同中约定的其他不能补焊的重大缺陷。在补焊前应判断缺陷的类型。 2、缺陷剔除在工厂里一般可采用碳弧气刨吹去铸造缺陷,然后用手提角磨机打磨缺陷部位至露出金属光泽。但生产实践中更多的是直接用碳钢焊条大电流除去缺陷,并用角磨机磨出金属光泽。一般铸件缺陷剔除,可用<4mm-J422焊条,160～180A电流,将缺陷除干净,角磨机将缺陷口打磨成U形,减少施焊应力。缺陷清除的彻底,补焊质量好。 3、缺陷部位预热碳素钢和奥氏体不锈钢铸件,凡补焊部位的面积<65cm2,深度<铸件厚度的20%或25mm,一般无需预热。但ZG15Cr1Mo1V、 ZGCr5Mo等珠光体钢铸件,由于钢的淬硬倾向大,冷焊易裂,应作预热处理,预热温度为200～400℃(用不锈钢焊条补焊,温度取小值),保温时间应不少于60min。如铸件不能整体预热,可用氧-乙炔在缺陷部位并扩展20mm后加热至300-350℃(背暗处目测观察微暗红色),大号割炬中性焰枪先在缺陷处及周边做圆周快速摆动几分钟,然后改为缓慢移动保持10min(视缺陷厚度而定),使缺陷部位充分预热后,迅速补焊。

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