中国微合金化技术与含铌钢发展30周-of Evolution(3)

中国微合金化技术与含铌钢发展30周-of Evolution

22 中国含铌钢技术发展30周年国际研讨会论文集

processing regimes were established. The available strengthening mechanisms used today can be depicted as simple incremental building blocks as illustrated in Figure 2.

Figure 2: Required combination of strengthening components for hot rolled plate and skelp. These strengthening components are all utilized to varying degrees in modern high strength linepipe.

Microalloyed Steels in Linepipe Applications

The first reported use of microalloying techniques in linepipe steels occurred in Europe (Mannesmann) in normalized API Grade X-52 vanadium grades around 1952. This was later extended to API Grade X-56 and X-60 in 1953 and 1962 respectively [15-16].

Hot rolled steel utilizing microalloying concepts emerged in North America in 1959 [1, 17] and completely replaced normalizing in Europe by 1972 [15-16]. However normalizing of medium carbon (0.17%) microalloyed steel was still used in the Soviet Union until the mid 1990’s. The new hot-rolled semi-killed medium carbon steel [1] shown in Table 1 below, was substituted for steels having much higher carbon and manganese contents thereby improving field weldability.