Steel strength level

The grades of steel most commonly used in the chemical-process industries have tensile strength in the 345- to 48.5-MPa (50,000 to 70,000-lbf/in") range, with good ductihty. Higher strength levels are achieved by cold work, alloying, and heat treatment. 

The mechanical and physical properties of some alloys chosen for rebar in concrete are relevant in the performance of the alloys. The mechanical properties of some reinforcing bar alloys are given in Table 7.11. All the steels except duplex steels were subjected to cold work in order to increase their strength. Duplex S31803 steel in the annealed state exhibits strength levels close to the values of the cold-worked alloys. 

Heat treatment is more widely used than cold work to strengthen metals because final properties can be tailored to design requirements and additionally achieve much higher strength levels. Not every metal may be heat treated. For example, the only way of strengthening austenitic stainless steels (300 series) is by cold work. 

The martensitic and precipitation-hardening stainless steels are more susceptible to hydrogen embrittlement than are the austenitic alloys. The susceptibility of these stainless steels is sensitive to microstructure and strength level. Figure 22 shows the resistance to cracking for a martensitic (type 410) stainless steel and some precipitation-hardening stainless steels in an H2S-saturated solution [174]. The low resistance of type 410 stainless steel is typical for most... 

The stretch flangeability of multiphase steels is lower than that of single-phase steels at a particular tensile strength level, although stretchability of the former is superior to that of the latter. 

---