【摘要】 通过热裂试验和热塑性试验证实,低碳钢焊缝金属中存在结晶裂纹和离温失塑两类裂纹;脆性温度区间分别为1480～1450℃和1100～850℃。高温失塑裂纹表面形态是:沿晶塑性和带孔洞的光滑面,韧窝和孔洞中有(Mn、Fe) S夹杂物。增锰可以消除这种裂纹。对结晶裂纹和高温失塑裂纹的产生条件和形成原因进行了分折。提出硫在晶界的偏析和(Mn、Fe)S 沉淀,引起微裂纹的形成和集聚,产生塑性低落,可能是低碳钢焊缝金属中失塑裂纹形成的原因。更多还原

【Abstract】 The hot cracking tests and hot ductility tests verified that there are two types ofhot cracks in low—carbon steel weld bead:the solidification cracks and the ductility-dip cracks.Their brittleness temperature ranges are 1480—1450℃ and 1100—850℃respectively.The morphology feature of ductility—dip cracking is intergranular fracturewith dimples and smooth facets,and there are(Mn,Fe)S precipitates on the crackingsurfece.This type of cracking can the prevented by increasing the manganese content inthe weld metal.The formation conditions and possible cause of the cracking were discus-sed.The authors noted that microcracks due to sulfur segregation aud(Mn,Fe)S pre-cipitation at the austenitic grain boundaries may propagate and link up to form a lowductility fractuare.更多还原