Grain steels

Since the rate of formation of cementite is determined by nucleation, and therefore proceeds more rapidly in fine-grained steels, it follows that the T-T-T diagram will show a more rapid onset of austenite decomposition than in steels of the same composition, but a coarser grain size. The shape of the T-T-T curve is also a function of the steel composition, and is altered by the presence of alloying elements at a low concenuation. This is because the common alloying elements such as manganese, nickel and clrromium decrease... 

Use fully killed or fine grained steels in services below 750°F in critical locations. 

Use fully killed or fine grain steel, controlled rolling temperatures high Mn/C ratios eliminate sharp corners in design, remove defects from steel heat treat steel. For cryogenic operations use high nickel alloy steels or austenitic stainless steels, depending on temperature. 

CA 43, 3770(1949XManuf of cases from carbon fine-grained steels by cup and draw-case forming techniques) l6)Encycl-Britannica 2(1952), 787(Manuf of ctge cases) 17)... 

Liquid chlorine is generally stored in vessels made from nonalloyed carbon steel or cast steel. Fine grain steel with a limited tensile strength is used to ensure proper conditions for welding these containers. Erosion of protective layers on steel is prevented by maintaining the flow velocities to less than 2 m/s. Although organic materials, zinc, tin, aluminum, and titanium are not acceptable for liquid chlorine use, copper, silver, lead, and tantalum are acceptable for some equipment. 

Inhibiting nitrogen taken up by aluminum as Al N2 in fully killed and fine grain steels (nitrogen in steel stabilizes iron carbides.)... 

The approach to the problem of low-alloy, high-tensile steel for heavy-wall reactor vessels, on the other hand, has been different between the United States and Europe. The objective was the same — to produce a steel with high room temperature strength which is maintained at elevated temperature and with good notch ductility and weldability. This requires a fine-grain steel with low carbon and sufficient alloying elements to maintain strength at elevated temperature. 

The prototype of continental European steels is the German steel standardized in DIN 17100 as St 52.3. In practice, St 52 steel is usually supplied as a proprietary grade rather than to the DIN standard. Such fine-grain steels cost about 5% more than standard boiler plate, but the yield stress is increased by 50%, so that in German code construction they can offer a useful saving for vessels requiring thick plate. 

S. Hirano, K. Okamoto, K. Aota, and M. Inagaki, Metallurgical and Mechanical Properties of Friction Stir Welded Ultra Fine Grained Steel, Proceedings of the Fifth International Conference on Friction Stir Welding, Sept 14—16, 2004 (Metz, France), TWl, paper on CD... 

Q4. When rolling high quality fine-grained steel, what range of furnace exit... 

Weld construction steel and fine-grained steel using the MAG process (preferably in combination with Ar or Ar/Oj) (see Section 2.5.3, Example B)... 

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