軋延製程對含鈮高張力鋼板冶金性質影響

The Effect of Rolling Process on the Properties Of Niobium Bearing HSLA Steel Plate

10.30069/MM.199903_43(1).0010

邱方仁(Fon-Jen Chiu)

再結晶控制軋延 ； 控制軋延 ； 硬化能 ； 含鈮鋼 ； 肥粒鐵硬度 ； Recrystallization control rolling ； Hardebn-ability ； Control rolling ； Nb-steel ； Ferrite hardness

鑛冶：中國鑛冶工程學會會刊

43卷1期（1999 / 03 / 01）

118 - 126

繁體中文

以不同程序軋製厚度40 mm拉力強度500 MPa級鋼板，製程分為控制軋延及連續軋延二組。控制軋延之完軋溫度為880℃，因為連續軋延省去了休軋期，完軋溫度昇高至1000℃。檢驗試驗鋼板之機械性質，顯示連續軋延鋼板之強度高於傳統控制軋延，但是衝擊韌性值很低。經由比較控制軋延及連續軋延之兩種不同製程試片金相組織，發現鋼板經歷控制軋延之肥粒鐵晶粒較細，以波來鐵為主之第二相沿軋延方向呈帶狀分佈，但體積較小，而經歷連續軋延板之晶粒粗大，第二相碳化物亦很粗大，沒有呈帶狀分佈。計量冶金量測顯示連續軋延方式第二相體積百分率較控制軋延高。利用維氏硬度儀分別測量材料之整體硬度及肥粒鐵相硬度、二次相組織硬度後發現，鋼板經控制軋延之微觀組織肥粒鐵硬度遠小於經歷連續軋延者，兩種不同製程之二次相硬度並沒有很大的差異，顯示高溫完軋鋼板之肥粒鐵含有顯著的鈮合金析出強化效果。

Comparison of the effect of standard controlled rolling and continuous rolling processes on mechanical properties has been tried on line to produce 40 mm thick, 500 MPa tensile strength grade plate. The finish rolling temperature of controlled rolling is at 800 ℃., No holding period is used for continuous rolling, and the plate is finish rolled at 1000 ℃. The mechanical properties tests indicate that the continuous rolling process gives higher strength but a very poor impact value. Microstructure examination reveals finer ferrite grain size and elongated pearlite second phase for the controlled rolling process. Sample from the contiunuous rolled plate shows larger ferrite grain size and evenly distributed second phase carbide, and the quantitative metallography analysis shows higher volume fraction of the second phase. The controlled rolling samples have lower Vickers hardness values in bulk and lower microhardness value in ferrite but there is no difference in hardness in the second phases. This indicates that there is a significant amount of Nb precipitation strengthening occurring in the continuous rolling process. The higher strength of continuous rolling process can be explained by higher ferrite hardness and volume fraction of pearlite, but that also is the cause of deteriorated impact toughness. It is concluded that to produce thick Nb-bearing plate, it is still necessary to use the controlled rolling process.