The Importance of the Heat Affected Zone (HAZ)

When we weld we generate enough heat in the welding arc to melt the filler metal and base material.  Or just the base material is we are welding autogenously (as in GTAW without filler).  The edges of the base material melt and combine with the filler metal to create what is called the composite zone.  […]

Steps to determine if welding preheat can be eliminated?

Testing the effects of preheat in small parts and assuming it will be the same on large sections is a mistake.

As discussed in our previous article, and many times in the last 50 or so, preheat is necessary in steel welding to control the cooling rate.  More specifically, preheat is used to slow the cooling rate down in order to prevent excessive hardness in the heat affected zone (HAZ) which  can lead to cracking.   Before […]

Factors Affecting Cooling Rates of Welds and Heat Affected Zones

Different ways to manage the rate of cooling

Our next article will discuss a question we are asked quite often: Can we eliminate preheating before welding?   Preheating is necessary to slow the cooling rate down after welding which in turn avoids excessive hardening of the weld and heat affected zone.  Eliminating preheat can lead to hydrogen induced cracking and catastrophic failure.  A […]

Should Heat Input Always Be Kept As Low As Possible?

Many ‘experts’ in the welding industry talk about high heat input as something that should always be avoided.  Unfortunately, this is not good advice.  High heat input can be detrimental in many cases, but other times we want to have higher heat input. Heat input is directly related to amperage and voltage and inversely related […]

Understanding Why Your Welds Crack – Part 3

Location of Cracks

Cracks can be categorized by their location: weld metal, heat affected zone and unaffected (by heat) base metal.

In our previous two articles we talked about categorizing cracks based on when they occur and in which direction they propagate.  Today on our third and final article on understanding why your welds crack we look at the importance of location. If you want to review or if you missed our previous two articles simply […]