16NCD5结构钢 面议 C50580-H04铜合金棒C50580-H04化学成分板C50580-H04材质证明盘条带 面议 20NiCrMoS6-4 面议 16NCD17 结构钢 面议 C50580-H08铜合金棒C50580-H08化学成分板C50580-H08材质证明盘条带 面议 C50780-H02铜合金棒C50780-H02化学成分板C50780-H02材质证明盘条带 面议