A typical circumferential crack formed during the open-die forging

A typical circumferential crack formed during the open-die forging - Ingot defects

Figure 1: A typical circumferential crack formed during the open-die forging of a 6-ton low alloy steel ingot.

Figure 2: Photograph of a 6-ton low alloy steel ingot during the open-die forging the similar ingot. Note that no crack is formed in the intersection of the hot top (right) and ingot (left).

Table 1: Chemical compositions of ingot and mould.

Table 2: Experimental conditions used for the simulations.

Defect name: Crack
Record No.: 3343
Type of defect (Internal/Surface): Surface
Defect classification: Forging defects, ingot defects
Steel name: Steel
Steel composition in weight %: No data.
Note: Today’s forging industry requires a wide range of raw materials, all of which must meet certain standards that limit the quality of the semi-finished products. In addition to imparting a certain shape and geometric dimensions, the forging process eliminates defects in the initial semi-finished product as it breaks up coarse-grained dendritic structures and nonmetallic inclusions. Thus, the final product is characterized both by the inherited macrostructural nonuniformity of the ingot and by the nonuniformity which results from plastic deformation. However, cracking may occur during hot forging of steel ingots originating from the cast microstructure or unsuitable forging conditions. The intersection between the hot top (riser) and ingot is a critical region in which circumferential cracks could form during the primary stages of forging. The crack then propagates into the ingot and leads to high crap formation. Fig. 1 shows a typical circumferential crack that is formed during the open-die forging of a low alloy steel ingot.

Fig. 2 shows the photograph of the same ingot shown in Fig. 1 that is successfully hot forged and no crack is formed during forging. This ingot was cast under constant pouring rate of 7 kg s(-1) (i.e. the pouring rate in hot top is double compared to the one in Fig. 1). It confirms that increasing pouring rate in hot top of P64 ingot resulted in reducing crack susceptibility in the critical intersection of hot top and mould ingot.
Reference: Not shown in this demonstration version.