Metallography
The microstructure of BethStar 80 plate is essentially a combination of ferrite and pearlite. Figures 20A and 20B illustrate representative microstructures at original magnifications of 200X. The material is extremely fine grained with a typical grain size of ASTM 12 and finer.

Effect of straining, aging and stress-relieving on properties of BethStar 80
BethStar 80 responds to cold straining in much the same manner as other materials. Small amounts of strain result in modest increases in strength and modest decreases in ductility and notch toughness. Aging after straining results in slight further emphasis on these changes. Proper stress relief annealing will essentially restore the original notch toughness and tensile properties.

Ref. Figure 18	Ref. Figure 19

Formability
This excellent formability is associated with the low sulfur and the relative absence of stringer manganese sulfide-type inclusions. Figure 1 (page 2) shows 3�8 in. plate that was bent to a 1�2 T bend radius and no evidence of failure can be seen.BethStar 80 plate can be readily formed at room temperature if adequate power is available and proper procedures are following. The suggested minimum inside radius for forming the 80,000 psi yield strength plate, as a function of thickness, is given below.

Precautions
The following precautions should be taken for severe bending operations.
1. The largest radius permissible should be used.
2. Major bends should be made on a line which is perpendicular to the length of the plate (rolling direction), if possible.
3. The outside radius should not be restrained. Closed-die forming may require doubling the suggested radii to avoid breakage.
4. Sharp notches on the edge of plates, resulting from shear breaks or torch cutting, require removal by grinding or machining to prevent cracking during severe forming.
5. Roll forming of cylindrical sections should be preceded by crimping of the butt edges before forming.
6. Extremely severe forming should be done hot, after heating the plate to 1100�F max.

Representative microstructures of BethStar 80 plates at an original magnification of 200X - 1/4 in. (Fig. 20A) and 3/4 in. (Fig. 20B).

Figure 20A	Figure 20B

BethStar Steel Plate BethStar Characteristics BethStar 50 (page1) BethStar 50 (page 2)
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