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采用热模拟试样研究了 ＨＱ－７０钢热影响区的性能和组织。试验了焊后５００～７００℃ 回火对过热区韧性的影响。结果表明ＨＱ－７０钢在该区具有再热脆性。出现再热脆性的 主要原因是晶界粗大碳化物的析出和晶内二次硬化。此外，磷在晶界的偏也是另一重 要原因。
Thermal simulation specimens were used to study the properties and microstructure of HQ-70 steel heat affected zone. The effect of tempering at 500 ~ 700 ℃ after welding on the toughness of overheated zone was tested. The results show that HQ-70 steel has re-thermal brittleness in this zone. Reheat brittleness is the main reason for the occurrence of coarse grain boundary precipitation and intragranular secondary hardening. In addition, phosphorus in the grain boundary of the bias is another important reason.