Can You Explain These Concepts About Welding?

On the cross-section of the weld, the distance between the two weld toes is called the weld width, also known as the weld width, as shown in the figure:

On the cross-section of the weld, the melting depth of the base metal is called penetration, as shown in the figure above; penetration directly determines the bonding strength of the weld and the base metal, and also determines the load-bearing capacity of the weld to a large extent.

The maximum height of the part of the weld beyond the surface of the workpiece is called reinforcement, which is the distance from the vertex of the weld to the line connecting the two weld toes. See picture above. For fillet welds, reinforcement is also called crowning. The strengthening of the weld increases the cross-sectional area of ​​the weld and improves the static load carrying capacity. However, too high a height will cause stress concentration at the weld toe and reduce the ability of the weld to withstand dynamic loads. For weldments subject to dynamic loads or fatigue, the reinforcement ribs of butt welds should be ground flat, and the reinforcement ribs of fillet welds should be ground into a concave shape.

The ratio of melt width to reinforcement (B/a) is called the reinforcement coefficient. For butt welds, it should generally be 4~8 (or steel bars should be 0~3mm).

In the cross-section of the weld, the distance from the root of the weld to the line connecting the two weld toes is called the weld thickness, represented by h, as shown in the figure.

In the cross-section of the weld, the maximum distance from the root of the weld to the surface of the weld is called the actual thickness of the weld, expressed by hs. The calculated butt weld thickness hj is equal to the weld thickness. For fillet welds, the calculated thickness is equal to the distance from the intersection of the inner surfaces of the two workpieces in the cross-section of the weld to the line connecting the two weld toes;

In the cross-section of a fillet weld, the distance from the weld toe of one weldment to the original surface of the other weldment is called the weld leg, as shown in the figure. The size of the welding leg determines to a large extent the bonding strength between the weldment and the weld, thereby determining the connection strength of the weld. It is the most important parameter of fillet welds.

In the cross-section of a concave angle weld, the maximum distance between the weld toe line and the weld surface is called concavity, as shown in the figure. Fillet welds subjected to dynamic loads usually require grinding to a certain concavity.

The ratio of the melt width to the calculated thickness of the weld is called the weld forming coefficient φ. The weld forming coefficient not only determines the weld shape, but also has an important influence on pores, crack sensitivity and molten pool crystallization conditions. For arc welds, the weld forming coefficient is generally required to be greater than 1. The influence of weld forming coefficient on weld quality is as follows. ①The smaller the impact on stomatal sensitivity φ, the greater the stomatal sensitivity. ②Influence the crystallization direction. When φ<1, it crystallizes toward the center; when φ>1, it crystallizes upward, as shown in the figure. ③Influence on central segregation. If φ is too small, segregation will occur, and in severe cases, thermal cracking may occur.