roll barrel的用法和樣例：
例句
- The roll barrels are mainl composed of pearlitic or temper sorbite in the microstruscutre.
輥身金相組織為珠光體或回火索氏體。 - Propagation develops within the working surface of the roll, gradually increasing in depth and width followed by a large surface spall of the overlying barrel surface.
這種斷裂首先是在工作層中產生的，進而逐漸往輥身方向變深變寬，最終導致輥身大面積的剝落。
