|
Di-Hard Alloy Cast Steel
|
 |
 |
Di-Hard differentially hardened rolls were developed to overcome the compromise between strength and wear resistance which is so often a problem when manufacturing conventional rolls.
In the differential hardening process, the rolls are first treated to produce the optimum structure for meeting the mechanical requirements of the mill and then the barrel surface layer is hardened to a controlled depth by means of a special rotary SELAS furnace. In the case of grooved rolls, by machining the pass grooves before SELAS treatment the hardness contour can be made to follow the barrel profile thus ensuring adequate hardness at the bottom of the passes at discard.
Thus, Di-Hard rolls combine maximum resistance to breakage with excellent wear and surface finish and are capable of tonnage outputs substantially higher than those of conventional rolls. The high strength and spall resistance of the hardened layer makes the rolls particularly suitable as backup rolls.
The characteristics of the barrel surface material result in a very fine fire crack pattern so that Di-Hard rolls work very well in Primary Mills.
|
|
Applications
|
|
| Product |
Type of Mill |
Position |
| Slab |
Universal |
Horizontal & Vertical |
| Slab |
High Lift |
|
| Blooms |
2 & 3 High |
All Positions |
| Plate |
4 High |
Work and Backups |
| Wide Strip |
2 & 4 High |
Roughing & Backup |
| Beam Blanks |
2 High |
|
| Heavy Sections & Rails |
2 & 3 High |
All Positions |
|
Typical Mechanical Properties
|
|
|
N/mm2 |
|
| Property |
Barrel Surface |
Journals & Axis |
| Tensile Strength |
1350 |
750 |
| Bending Strength |
1850 |
1030 |
|
Typical Hardness Gradient
|
|
|
|
|
Micrograph. Barrel Surface x 100
|
|
|
|
Typical Analysis
|
|
| Code |
Leeb E |
Shore C |
C |
Si |
Mn |
Ni |
Cr |
Mo |
| DH2 |
555-620 |
45/55 |
0.6/1.0 |
0.3/0.8 |
0.5/1.1 |
0.4/0.8 |
0.5/1.0 |
0.2/0.5 |
| DH6 |
555-620 |
45/55 |
0.6/1.0 |
0.3/0.8 |
0.5/1.3 |
1.0 max |
1.5/2.5 |
0.2/0.5 |
| DH3 |
590-650 |
50/60 |
0.6/1.0 |
0.3/0.8 |
0.5/1.1 |
0.7/1.2 |
0.7/1.2 |
0.3/0.6 |
| DH4 |
620-680 |
55/65 |
0.3/0.7 |
0.3/0.8 |
0.5/1.1 |
1.0 max |
2.5/3.1 |
0.3/0.6 |
| DH8 |
620-680 |
55/65 |
0.6/1.0 |
0.3/0.8 |
0.5/1.3 |
1.0 max |
2.0/2.5 |
0.3/0.6 |
| DH7 |
650-710 |
60/70 |
0.3/0.7 |
0.3/0.8 |
0.5/1.1 |
1.0 max |
3.0/3.6 |
0.3/0.6 |
|
