镀铜合金焊丝表面色差分析与改进

Analysis and improvement of surface color difference of copper plated alloy welding wire

针对镀铜合金焊丝表面色差问题,通过SEM、能谱分析等手段,发现对于Si含量较高的ER70S-G合金焊丝用钢,其铸坯表面易出现难以去除的Fe_(2)SiO_(4)氧化铁皮和氧化裂纹,随着轧制和盘条拉拔遗传到焊丝表面,造成焊丝产品镀铜不良而导致表面发黑。同时,研究了Fe_(2)SiO_(4)氧化铁皮和氧化裂纹与铸坯加热温度、加热时间和残氧含量关系,加热温度在1150℃以上时,Fe_(2)SiO_(4)相比例显著增加;在1100℃高温条件下,随着加热时间的延长,氧化反应持续发生,氧化裂纹显著加深;炉内残氧含量越高,铸坯氧化速率越快;10%残氧含量铸坯的氧化速率是2%残氧含量时的4倍。为此,采取对加热炉加设挡墙以及采用一空一装坯方式,控制加热时间约80~90 min,入炉温度小于750℃,加热一段温度为770~820℃,加热二段温度为950~980℃,均热段温度为1050~1100℃的措施,解决了高Si含量焊丝产品镀铜表面发黑的问题。

The surface color difference problem of copper plated alloy welding wires was studied by SEM,EDS etc.It was found that for alloy welding wire steel with high Si content,such as ER70S-G,iron oxide scale with Fe_(2)SiO_(4) and oxide cracks were prone to appear on the surface of the cast billet,which were difficult to remove.After rolling and wire rod drawing,they were inherited to the surface of the welding wire,causing poor copper plating and resulting in surface blackening.The relationship between Fe_(2)SiO_(4),iron oxide scale,oxide cracks and the heating temperature,heating duration,and residual oxygen content was studied.When the heating temperature was above 1150℃,the proportion of Fe_(2)SiO_(4) in the iron oxide scale significantly increased.Under 1100℃,oxidation reactions continued to occur and oxidation cracks significantly depened with the prolongation of heating duration.The higher the residual oxygen content in the furnace,the faster the oxidation rate of the billet.The oxidation rate of billets under a 10%residual oxygen content was four times that of a 2%residual oxygen content.To solve the color difference troubles,two retaining walls were added to the heating furnace and a special billet loading method is adopted.Thus the heating duration is cut down to be about 80-90 minutes.The temperature of furnace entrance is decreased to be less than 750℃.The first heating stage temperature is about 770-820℃,the second heating stage temperature is about 950-980℃,and the uniform heating stage temperature is about 1050-1100℃.This heating process solves the surface blackening problem of the high Si content welding wire products.