black heart malleable castings

例句：

1. 1.The black heart malleable castings are used in the production of high-quality steel.
   这些可锻铸铁件用于生产高质量的钢材。
2. 2. The black heart malleable castings are known for their strength and durability.
   这些可锻铸铁件因其强度和耐用性而闻名。
3. 3. The black heart malleable castings are widely used in various industries due to their excellent mechanical properties.
   由于其出色的机械性能，这些可锻铸铁件在各个行业中得到了广泛应用。