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.  […]

How to Avoid Sensitization When Welding Austenitic Stainless Steels

Stainless steels are iron based alloys that contain a minimum of 10.5% chromium.  This chromium reacts with the air and forms a very thin but very tenacious chromium oxide layer which is what prevents stainless from rusting. There are 5 types of stainless steels which are categorized depending on additional alloying elements.  One thing they […]

Common Mistakes That Lead to Hydrogen Induced Cracking

Even when a qualified welding procedure is in place

Hydrogen Induced Cracking (HIC), also called hydrogen assisted cracking (HAC) and cold cracking, is a common welding defect when welding heavy steel sections and steels with high carbon content.  If you would like to learn more about the causes of HIC read Factors Influencing Hydrogen Induced Cracking. In the above mentioned article we explained that […]

What is Stress Relieving and Why We Need It

Stress relieving is a form of post weld heat treatment. In stress relieving we heat a material to a specific temperature; hold it at this temperature for a specified amount of time in order to reduce or eliminate residual stresses; and then cool it at a slow enough rate to prevent these stresses from redeveloping. […]

Is Weld Strength Affected by Shielding Gas Mix?

Can our selection of shielding gas affect the strength of a weld and other important mechanical properties?  Absolutely!  The difference is more pronounced when using flux-cored (FCAW) wires than when using mig (GMAW) wires, especially as the wire’s tensile strength goes up.   Although we can affect strength by using different gases, what we should be […]

Importance of Weld Failure Analysis

Basic guidelines to troubleshoot weld failures

When a weld fails we don’t always know what caused it.  We may try something different and if it doesn’t fail the next time we adopt that as the new standard.  However, it is very important to know the root cause of weld failures.  If we don’t know what caused the failure how can we […]

What is Post Weld Heat Treatment (PWHT)?

What is it? Why is PWHT needed? How is PWHT done?

Have you heard of post weld heat treatment (PWHT)? Of course you have. If you are involved in welding you have definitely heard this term.  But what is PHWT? When is PWHT required?  What temperature should PWHT be done at?  Heat treating of materials can be a very complicated subject, but when it comes to […]

Preventing Hydrogen Induced Cracking

Our last post (Factors Influencing Hydrogen Induced Cracking) went over the factors that contribute to hydrogen-induced cracking.  We will now go over how to prevent HIC from happening.  If you recall, we mentioned you need all three factors to be present in order to have HIC:  These factors are 1. a susceptible microstructure, 2. threshold […]

Factors Influencing Hydrogen Induced Cracking

Hydrogen-induced cracking (HIC) is a far too common type of failure. It is also called hydrogen assisted cracking (HAC) and delayed cracking since it does not occur right after welding, but a few hours or days after the weld has completely cooled down to ambient temperature.  Cracking occurs due to a significant loss in ductility […]

Understanding Weld Discontinuities

Not all discontinuities are defects

Not all weld discontinuities are weld defects, but all weld defects are discontinuities. Understanding the difference will let you know if you need to scrap a part, repair it or simply add more weld. There are many codes depending on what type of product you are welding on. The codes are used as guidelines by […]