Rupture strength

Rupture strength data for several of these alloys also ate available (53). 

It was concluded that 1.5Ti-3.0Al should be considered the most suitable alloy for ECC flue gas expander rotors. A 1,400-mm diameter expander rotor disk was manufactured using this alloy. Test specimens removed from the disk rim showed that the disk had equivalent tensile properties at both room and elevated temperatures, and the same creep rupture strength as that of AISI 685. 

For resistance against fatigue, Nimonic 75 has been used with Nimonic 80 and Nimonic 90. Nimonic 75 is an 80-20 nickel-chromium alloy stiffened with a small amount of titanium carbide. Nimonic 75 has excellent oxidation and corrosion resistance at elevated temperatures, a reasonable creep strength, and good fatigue resistance. In addition, it is easy to press, draw, and mold. As firing temperatures have increased in the newer gas turbine models, HA-188, a Cr, Ni-based alloy, has recently been employed in the latter section of some combustion liners for improved creep rupture strength. 

In the 1980s, IN 738 blades were widely used. IN-738, was the acknowledged corrosion standard for the industry. New alloys, such as GTD-111, were developed and patented by GE in the mid-1970s. GTD-111 possesses about a 35 °F (20 °C) improvement in rupture strength as compared to IN-738. GTD-111 is also superior to IN-738 in low-cycle fatigue strength. 

If some other criterion such as creep-rupture strength is of primary importance, the alloy choice may be restricted. Here it would be necessary to have thennal fatigue comparisons only for the alloys that pass the primary screening. When alloy selection reaches this stage some further cautions are in order. 

Good impact strength at low temperatures and excellent creep rupture strength. 

Oc is the creep rupture strength at a time equivalent to N cycles... 

Example 2.21 A rod of plastic is subjected to a steady axial pull of 50 N and superimposed on this is an alternating axial load of 100 N. If the fatigue limit for the material is 13 MN/m and the creep rupture strength at the equivalent time is 40 MN/m, estimate a suitable diameter for the rod. Thermal effects may be ignored and a fatigue strength reduction factor of 1.5 with a safety factor of 2.5 should be used. 

The austenitic grades, used mainly in the solution treated (softened) state, have low strength at ambient temperature but maintain strength at elevated temperatures much better than the martensitics and the ferritics. As can be seen from Figs 7.23 to 7.25, creep and rupture. strengths are far superior... 

Transverse Rupture Strength 240-390 MPa Coefficient of Friction 0.25 (on tool steel, 50% humidity)... 

Young s Modulus of Elasticity 620-720 GPa Shear Modulus 262 GPa Poisson s Ratio 0.18 Transverse Rupture Strength 550 MPa... 

Recently published laboratory creep studies22 have shown that the rupture strength and rupture ductility of 2.25Cr-lMo steel are diminished when tested in hydrogen as compared to their values in air. These tests were a continuation of previously-reported tests23, 25 that showed somewhat conflicting results in shorter term tests. 

E. B. Norris and E. A. Sticha, Effect of Hydrogen on the Stress-Rupture Strength of 2- 4Cr-lMo Steel, Metal Properties for the Petroleum and Chemical Industries (ASME G00103/MPC-2), American Society of Mechanical Engineers, New York, 1976, pp. 590-592. 

This is the most common test method employed to qualify the leak characteristics of a new seal material. The test method involves applying the seal between two ceramic discs or between a ceramic and a metal disc, pressurizing the cavity formed by the seal and monitoring the pressure decay as a function of time.22 Alternatively, a metal tube and a ceramic disc can also be used [34], Typically, the cavity is pressurized to about 2 psi and the leak rate is determined by the pressure decay as a function of time. These tests can be done at room temperature or elevated temperatures. Similar test arrangement has also been used to test a plastically deformable brazed metal seal between fuel cell anode material and Haynes 214 washer [35], The cavity is pressurized to measure the rupture strength of the seal material. 

Engineers and metallurgists have developed alloys to comply economically with individual codes. In Germany, where design stress is determined from yield strength and creep-rupture strength and no... 

Compound Molecula r formula Densit y> g/mL Mp, °C Micro hardness a Transvers e rupture strength, N/mm2b Compressio n strength, N./mm2b Modulus of elasticity, N/Wb Heat conductivity, W/(cm-K) Coefficien t of thermal expansion, (3 x 10 6 Electrical resistivity, /iO-cm... 

In addition to chemical analysis a number of physical and mechanical properties are employed to determine cemented carbide quality. Standard test methods employed by the industry for abrasive wear resistance, apparent grain size, apparent porosity, coercive force, compressive strength, density, fracture toughness, hardness, linear thermal expansion, magnetic permeability, microstmcture, Poisson s ratio, transverse rupture strength, and Young s... 

Hardness and solubility for other carbides make TiC an important component of sintered cemented carbides. Although the addition of TiC or WTiC2 to WC—Co alloys imparts crater wear resistance, it also reduces the transverse rupture strength and fracture toughness of these alloys. Therefore, the amount of TiC or WTiC2 added to WC—Co alloys for steel machining is kept to a minimum, typically no greater than 10 wt %. The TiC-based cermets, on the other hand, may contain 30—85 wt % TiC. 

An absolute upper limit on operating temperature exists for any given fluid and vessel combination. This limit is determined by the creep or rupture strength of the vessel, ie, the ability of the vessel to contain the increasing vapor pressure of the working fluid. 

This is one of the reasons for the observed decrease of the rupture strength in quick deformation processes (brittleness). 

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