Hydrogen In Wear Resistant Steels
Hydrogen (H) is the lightest known element and is highly flammable when exposed with oxygen in the air. If you’re old enough or a history buff, you may recall the most famous Hydrogen disaster. The German airship Hindenburg, on May 6, 1937, blew up while trying to land at Lakehurst Naval Air Station in New Jersey.
Yet Most People Have No Idea Hydrogen Is Often Responsible For Cracks In Their Steel Wear Plate
When Hydrogen is trapped during the steel making process, or in a secondary process such as welding; it leads to residual stress cracking.
This steel wear plate on a papermill log deck has countless cracks that have been chased and welded during every maintenance shut down. If you bet that Hydrogen was the culprit in creating the cracks in this AR450, you’d likely win.
When Hydrogen diffuses, it is trapped within the molten steel. At some point in the future, the Hydrogen will work its way out of the solid steel, forming a crack. This usually comes out in a weld, or the area where you heated steel. It does this to relieve the stress in the steel.
When you reduce and control the Hydrogen content during the steel mill production, you decrease the potential for cracking after it is installed.
The distinction of JADCO QT-PLUS ® compared to other abrasion and impact resistant steels, is we concentrate on making it extremely user friendly. This means it is easy to form and weld with the proper welding alloys.
Everyone working with metal has heard of ‘Low Hydrogen’ welding rods. These are welding alloys specified designed for structural welds on pressure vessels and building structures. This is directly accomplished by keeping the moisture away from the cellulose flux, which acts like a sponge for humidity. Any moisture present on the flux coating, splits the water molecules into Oxygen and Hydrogen elements from the heat generated when welding. Rather than disperse into the air, Hydrogen goes into the metal, where it must work its way out over time.
JADCO recognizes our customers seldom have ideal conditions when mounting it in their equipment. For example, if you are welding on a bulldozer at a job site, you have a limited amount of time for the repair. This means you do not have the luxury of working in a nice dry environment. JADCO helps you by delivering the lowest Hydrogen content available in wear resistant steel. When you look at QT-PLUS ® with the naked eye, you would not know this procedure was done.
In the above image from our steel mill test report, Hydrogen is the only element listed in Parts Per Million, and not as a percentage. To the best of our knowledge, JADCO is the only wear resistant steel company that reports Hydrogen levels from the steel mill. Our steel mill certification test reports are far more comprehensive than any of our competitors.
Why Do We Pay Such Careful Attention To Hydrogen Levels? We Are Reducing The Potential For Cracking In The Future.
When you are working in the field, this makes all the difference in your results, and avoiding maintenance work in the future.
NOTE: At this point if you are questioning the accuracy of this information, Click Here.
(This PMC Pub Med Central article on Hydrogen Embrittlement (HE) backs up our claims.)
This is just one more way JADCO is looking out for our customers, who will need to do the cutting and welding on their equipment.
You will never see the information we publish on our competitor’s AR400 or 500 test reports in their published product data. They only list the chemical percentages. JADCO’s QT-PLUS ® delivers greater performance IN YOUR MOST CHALLENGING WEAR APPLICATIONS, than the various AR400 steel you have used previously.
We publish the fact that JADCO’s QT-PLUS ® delivers 3 to 5 times longer wear life than AR400 commodity wear steel. This is the wear steel commonly offered by most steel distributors and service centers.
Being able to create wear resistant steel having the same hardness throughout the entire thickness of the steel, demands you accurately control the alloying chemistry, along with precise heat treating.
Doesn’t Every Steel Company Make Their Wear Plate Last As Long As JADCO QT-PLUS ®?
The immediate answer is No; although the attention to detail required at the steel mill for the alloy content, is available to anyone. Yet most wear plate distributors choose to reduce the quantities and percentages of these essential alloying elements, trying get a lower selling price.
When You Cut Back On The Critical Alloys, Your Wear Life Drops. And It Is Always The Customer Who Suffers.
JADCO remains on your side to deliver the best possible wear performance.
For over 45 years, JADCO has focused exclusively on delivering consistent, longer life for our customers.
We are able to deliver better results to our customers, because we think differently. How? By concentrating on improving your wear life results compared to the wear plate you are currently using.
Allow us to help you today by emailing us at info@jadcomfg.com or calling (724) 452-5252.
We will schedule a meeting with one of our local wear plate specialists at a time that best fits your schedule.
Remember, the only thing you have to lose by not working with JADCO, are your profits.
When your usual clad plate gives out, give JADCO a shout!
The following information on Hydrogen Embrittlement is posted online from the US government agency, National Library of Medicine.
For more information, review this article, Hydrogen Impact: A Review on Diffusibility, Embrittlement Mechanisms, and Characterization article online, at PMC Pub Med Central, from the national Library of Medicine.
Article Excerpt
Hydrogen embrittlement (HE) corresponds to the abrupt degradation of mechanical properties of materials in the presence of hydrogen. Hydrogen embrittlement failure in metals was first recognized by Johnson in 1875 and has been observed in many metallic materials such as steels, aluminum alloys, titanium alloys, and superalloys. This problem in metals has been of great concern in various industries including chemical, petrochemical, power, and marine industries.
It has been generally established that hydrogen may reduce the macroscopic and microscopic tensile strength, fatigue strength, and fracture toughness, while its effect on the rate of fatigue crack growth is still debated, depending on the stress level ratio or frequency. Although extensive studies on the hydrogen embrittlement of metals have been carried out, many issues are yet to be understood. The phenomenon of hydrogen damage is a challenging basic research problem. One main reason for the damage caused by hydrogen in metals and alloys is the extremely small size of the hydrogen atom, which makes it move very fast in the metallic lattice. It is therefore not surprising that over the years, considerable research effort has been directed toward obtaining an understanding of this phenomenon.
Hydrogen-induced failures arise because cracks are able to grow to critical dimensions, with the initial stress intensity level increasing to the point under the requirement that K = KIC, where K is stress intensity factor and KIC is the critical stress intensity factor.
Such crack extensions can occur through a number of processes. Subcritical flaw growth mechanisms involving a cooperative interaction between a stress and the environment, leading to hydrogen embrittlement, and the final failure typically occurs after a period of time, rather than when exposure begins.
This damage mechanism affects many important alloy systems, most notably high-strength steel. When atomic hydrogen is introduced into an alloy, the toughness and ductility can be reduced dramatically, and subcritical crack growth can occur. Body-centered cubic and hexagonal close-packed metals are most susceptible to hydrogen embrittlement. Face-centered cubic metals are not generally susceptible to hydrogen embrittlement. Hydrogen has a very high mobility in the BCC lattice of carbon and low-alloy steels.
