permanent expansion meaning in English

持久膨账
永久膨胀
永膨胀

Sealed iron - nickel - cobalt alloy with permanent expansion
定膨胀封接铁镍钴合金
Iron - nickel alloy 4j58 of permanent expansion for line rules
线纹尺用定膨胀铁镍合金4j58
Non - magnetic and porcelain sealed nickel alloy of permanent expansion
无磁定膨胀瓷封镍基合金
Sealed iron - nickel - chromium , iron - nickel alloy with permanent expansion
定膨胀封接铁镍铬铁镍合金