Tempering steels

Anlass-farbe, /. (Steel) temper color (Leather) graining color, -harte,/. tempering hardness, -hartung,/. temper hardening. 

Fig. 8.20 Effects of different temprering times upon the time to failure ratio of two steels tempered at various temperatures (after Parkins el al )...

Most martensitic steels are hardened by heat treatment. These steels tempered below 425°C have good corrosion resistance. When the steels are tempered at about 425-540°C, resistance to SCC and hydrogen embrittlement is increased. The corrosion resistance of the steels in potable water and high-purity water at high temperature is satisfactory. These steels are highly resistant to flow erosion and erosion-corrosion. These steels are useful in applications such as boat propellers, propeller shafts and pump impellers. 

Similar results were obtained by Clerbois et a1 (45). These authors compared the current-potential curves of two 18 /B stainless steels tempered for two hours at 650°C one of the steels was Ti-stabilized and the other contained no Ti. The Ti-free-steel (A. LS. I. 302) shows a characteristic peak in 20% H2SO4 at a potential of - 50 mV. This peak corresponds to cfee corrosion sensitization of the grain boundaries. The Ti-stabilized steel (A, l. S. L 347) is not sensitized by the same tempering and does not show any peak at - 0.50 mV (Fig, 20). Similar observations have been presented more recently by Serge and Jacquet (4c). 

The ozonator was constructed of stainless steel. Tempered glass windows were bolted on each end of the assembled ozonator, using steel rings. Cooling water was supplied and withdrawn at connectors located on top of the ozonators. The dimensions were ... 

In very hard tool steels, for example, cold work steels tempered at low temperature, the wear resistance is originated mainly by hypereutectoid carbide which is not affected by hardening. These carbides are very small and evenly distributed and very hard (heavy-duty... 

Figure 5.6. Fractographic evidence on 0.45C-Cr-Ni-Mo steel, tempered at 800°F, showing the difference in inclnsion content at different snlfur levels [5].

Equation 6.14 provides a formal connection between creep crack growth and the kinetics of creep deformation in that the steady-state crack growth rates can be predicted from the data on uniaxial creep deformation. Such a comparison was made by Yin et al. [3] and is reconstructed here to correct for the previously described discrepancies in the location of the crack-tip coordinates (from dr/2 to dr) with respect to the microstructural features, and in the fracture and crack growth models. Steady-state creep deformation and crack growth rate data on an AlSl 4340 steel (tempered at 477 K), obtained by Landes and Wei [2] at 297, 353, and 413 K, were used. (AU of these temperatures were below the homologous temperature of about 450 K.) The sensitivity of the model to ys, N, and cr is assessed. 

Type Corrosion resistant plastic mold steel (good machinable) Tempered mold steel Tempered and hardened mold steel (highly polishable and etchable)... 

Figure 6.17 (a) Manson—Coffin curve for different martensitic steels tempered at 9—10% Cr, T = 550°C [43] (b) fatigue crack initiated at the free surface (left) and propagating in-depth (right). One pixel = 1 pm. Steel grade 91, pure fatigue, E/2 — 0.35%, 550°C [46]. 

T) In heat treatment, to reheat hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing hardness and increasing toughness. The process is also sometimes apphed to normalized steel. (2) In tool steels, temper is sometimes inadvisably used... 

The half-time to reach the steady state hydrogen permeation flux, which corresponds to the apparent hydrogen diffusivity in the metal, was four times longer in the Ce-bearing steel than in the non-Ce steel in the 480 K temper condition and 2.5 times longer in the Ce-bearing steel than in the non-Ce steel tempered at 670 K. These results indicate that... 

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