Preheat is used when a base material, due to its chemical composition, thickness or level or restraint, is susceptible to cold cracking (hydrogen induced cracking). Knowing what temperature to preheat your base metal is sometimes a complicated matter. You may hear people say “preheat to 300F to be safe.” The reality is that 300F may […]
Today we’ll cover 5 more very important concepts that are governed by the AWS D1.1 Structural Welding Code (Steel). If you missed our last post with the first five questions simply click here. These concepts can show up as questions in the Certified Welding Inspector (CWI) Exam. As stated in our article from last week, […]
Regardless what position you hold, if you work in the welding industry you have heard of welding procedures specifications (WPSs). To some, a welding procedure simply means the selection of a few variables such as amps and volts. To others, these are the documents that govern all welding done in their facility. A […]
Preheat is necessary in certain carbon and low alloy steel applications to prevent hydrogen induced cracking, also known as cold cracking. Cold cracking susceptibility increases as the amount of carbon in steel and the thickness go up. The higher the carbon content the easier it is for the steel to harden. And, the thicker the […]
High carbon steels are those containing 0.45% carbon or higher. They are typically considered “hard to weld” because they are crack sensitive and are susceptible to undergoing significant changes in their physical and mechanical properties after welding. However, high carbon steels can be welded successfully and without problems by having a sound understanding of the […]
It is often incorrectly assumed that quenched and tempered (Q&T) steels are hard to weld or even completely unweldable. This assumption is inaccurate as most Q&T steels have great weldability. However, extreme care must be taken to prevent cracking or loss of certain mechanical properties. A very common quenched and tempered steel is ASTM A514. […]
Last week we had the pleasure of working with a fabricator of pressure vessels in order to help them reduce manufacturing costs. As mandated by the ASME Boiler and Pressure Vessel Code this fabricator had welding procedure specifications (WPSs) and procedure qualification records (PQRs) in place. These were properly written, tested and documented. The WPS […]
Preheating steel before welding is common practice. Sometimes we apply heat after we are done welding as well. Other times we apply heat between passes to maintain the minimum interpass temperature. Many use preheat simply because it is written in the WPS, but not really understand why it is necessary. Preheating is used for […]
