5Cr-0.5Mo Alloy Steels

The 5Cr-0.5Mo steel is a member of the heat-resistant chromium-molybdenum (Cr-Mo) alloy steel family. Piping materials made of 5Cr-0.5Mo are widely used for a variety of high pressure and high temperature services such as petroleum cracking facility, coking unit, fertilizer production system, steam facility, and other petrochemical & power applications. It exhibits good resistance to oxidation and creep at elevated temperatures with maximum applicable temperature of 1200°F [649°C]. It is usually used for the construction of power boilers, nuclear facility components, and various pressure vessels. Compared to 1.25Cr-0.5Mo and 2.25Cr-1Mo, the higher chromium content imparts considerable resistance to abrasion and erosion to the 5Cr-0.5Mo alloy steel.

Nominal Chemical Composition

Product Forms & Standards

Heat Treatment

The 5Cr-0.5Mo alloy steel shall not be furnished in as-rolled condition since without proper heat treatment the metallurgical structure is martensite with very poor toughness and extremely high hardness. Piping materials made of 5Cr-0.5Mo steel shall be furnished in annealed, isothermal-annealed, or normalized and tempered condition.

If normalized and tempered heat treatment is applied, the tempering temperature shall not be less than 1250°F [675°C]. As the rule of thumb, the 5Cr-0.5Mo alloy steel shall be normalized at 950°C, soaking for 30 minutes. After air cooling, the the steel shall be tempered at the optimum temperature of 780°C, soaking for at least 60 minutes. If annealing is applied, the steel shall be soaked at 900°C for 2 hours. It shall be subsequently cooled down to 650°C in furnace atmosphere followed by air cooling.