Rainbow Colors in Stainless Steel Welding

Are they good or bad?

We receive several calls about welding stainless and the beautiful rainbow colors, or lack thereof, on the weld and heat affected zone.  Is the tinting an indication of quality?  Are these colors acceptable? Do they show that the weld had enough heat to penetrate?  Why do they need to be cleaned?  The questions are endless. […]

4 Key Factors Affecting the Fatigue Life of Welded Structures

Designing for fatigue is very different than designing for static loads.  One of the biggest challenges is being able to estimate the loads, timing of the loads and duration of the loads.   If you look at a bridge you have to estimate the number of vehicles going on the bridge every day, the weight of […]

Estimating the Fatigue Life of Steel Welded Structures and Components

Using S-N curves and formulas from Clause 2 of AWS D1.1

Heat affected zone crack induced by hydrogen. The crack originates at point of high stress as hydrogen diffuses out of the weld and heat affected zone.

The majority of industrial equipment and welded structural components are subjected to repeated fluctuating loads. These loads are typically of magnitudes that are within the elastic region of the material and well below its yield strength. This means that any deformation of the structure caused by the applied stress will then return to its normal […]

5 Questions and Answers You Must Know for the CWI Exam

And fundamental principles for the fabrication of steel structures

If you have taken or hope to take the CWI exam you probably have searched for some practice exam questions.  In practicing for the code book portion of the test you may have come across a few questions for which you could find the answer, but didn’t really understand the importance of the question or […]

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 […]

Understanding Why Your Welds Crack – Part 2

Direction of Cracks

In our previous post we discussed categorizing cracks based on when they occur.  If you missed this you can read it at Understanding Why Welds Crack: Timing. As discussed in this previous article, cracks can and should be categorized based on three criteria: Timing – did the crack occur immediately after welding (hot crack), did […]

6 Mistakes That Can Lead to Cracked Welds

Cracks on welds are never good.  Welding codes always have allowances for porosity, undercut, weld sizes, and even weld profiles.  However, there is never an allowance for cracks.  Being a linear discontinuity, a crack will tend to propagate through the weld and into the base metal with relative ease, especially in cyclically loaded structures.  So […]

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 […]