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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.
Element | Wt. % |
---|---|
C | ≤0.15 |
Mn | 0.30-0.60 |
S | ≤0.030 |
P | ≤0.030 |
Si | ≤0.50 |
Cr | 4.00-6.00 |
Mo | 0.45-0.65 |
Product Form | Standard & Grade |
---|---|
seamless tube | ASTM A213 T5 ASME SA-213 T5 |
seamless & welded fitting | ASTM A234 WP5 ASME SA-234 WP5 |
seamless pipe | ASTM A335 P5 ASME SA-335 P5 |
forged pipe | ASTM A369 FP5 ASME SA-369 FP5 |
plate | ASTM A387 Gr.5 ASME SA-387 Gr.5 |
welded pipe | ASTM A691 5CR ASME SA-691 5CR |
forging | ASTM A336 F5 ASME SA-336 F5 |
forging | ASTM A182 F5 ASME SA-182 F5 |
casting | ASTM A217 C5 ASME SA-217 C5 |
cast pipe | ASTM A426 CP5 ASME SA-426 CP5 |
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.