Hydrogen embrittlement is a phenomenon that causes metals like steel, titanium, and aluminum alloys to become brittle. It occurs when hydrogen enters these metals, reducing their ductility and load bearing capacity. There are several ways hydrogen can get into metals, such as from acid cleaning, electroplating, welding, and heat treating. Once hydrogen is absorbed, even small amounts below detection levels can cause cracking or failure of parts, especially under stress. Proper baking and controlling hydrogen exposure during manufacturing processes can help prevent failures from hydrogen embrittlement.
Mainly focused on how hydrogen will get trapped in the weld bead and how it will causes the embrittlement which sometimes leads to hydrogen induced cracking.
Introduction to Physical Metallurgy Lecture NotesFellowBuddy.com
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Mainly focused on how hydrogen will get trapped in the weld bead and how it will causes the embrittlement which sometimes leads to hydrogen induced cracking.
Introduction to Physical Metallurgy Lecture NotesFellowBuddy.com
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
We connect Students who have an understanding of course material with Students who need help.
Benefits:-
# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
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An introductory presentation on corrosion and its prevention. Importance of corrosion, cost of corrosion, various forms of corrosion, and preventive methods are given.
Video lecture is available on YouTube on the link:https://youtu.be/xrBnxxN-RUw
For UG students of All Engineering Branches, Chemistry, Food Science, Polymer Science, Chemical Engg. etc.
An introductory presentation on corrosion and its prevention. Importance of corrosion, cost of corrosion, various forms of corrosion, and preventive methods are given.
Video lecture is available on YouTube on the link:https://youtu.be/xrBnxxN-RUw
For UG students of All Engineering Branches, Chemistry, Food Science, Polymer Science, Chemical Engg. etc.
With Chapter 7 we enter the second triad of Geeta describing "That" in the Mahavakya "That Thou Art". Here the Lord starts describing the "Goal of the Spiritual Science" the Supreme Self. In the beginning, Sri Krishna promises Arjuna that He would explain the entire science of Spirituality, both theoretical & practical aspects, to clear all his doubts. Then He proceeds to explain the two Prakrities, Para & Apara, of the Self. He describes the 8-fold lower Prakriti, the Apara, consisting of the 5 elements, Earth, Water, Fire, Air & Space, & mind, intellect & ego. Beyond all these is the Lords Para Prakriti, the Spark of Life, Pure Consciousness, which supports all life in the universe. The two aspects of the Self, as Purusha & Prakriti create the whole 'Jagat'- the world-of-change. The One Self forms the core of all life, & everything is hung on It as pearls in a neckless. Then the Lord describes Himself as the Dharma-the Law-of-Being of everything. All matter exist in the Spirit, but the Spirit is not in Matter. Matter is just Super-imposed on Spirit, to be alive. Maya with its 'Veiling" & 'Projecting' action prevents all from recognizing the Self within them.
This is a presentation based on the book "Invincible Thinking" by the Japanese spiritual guru Ryuho Okawa. He talks about some traits of leaders. More details at www.happyscience.org
A brief introduction to corrosion and types of corrosion, such as pitting corrosion.
Cavitations corrosion
Galvanic corrosion.
Fretting corrosion.
Crevice corrosion.
Intergranular and transgranular corrosion,
Stress corrosion
14 Types of Corrosion explained in an awesome manner
Update 26 June 2019: I have enabled the Download option and now everyone can download the "Types of corrosions" PPT and reuse the slides :) I wish I have done this earlier.
Follow my blogs at https://www.geekdashboard.com/
When you design your product, you put a lot of money, energy and consideration into achieving the best possible function, good appearance and high reliability. Corrosion, wear and fatigue resistance may not be the first factors you consider.
However, material selection is crucial to obtain a long service life and to avoid damage such as operation failure – for instance due to inadequate mechanical strength - or unacceptable appearance due to corrosion products.
If you choose the correct materials for your product from the beginning, you can prevent damage deriving from corrosion, wear and mechanical impact. In many cases, you may completely avoid corrosion by choosing a resistant material for its actual application environment.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
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Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
CW RADAR, FMCW RADAR, FMCW ALTIMETER, AND THEIR PARAMETERSveerababupersonal22
It consists of cw radar and fmcw radar ,range measurement,if amplifier and fmcw altimeterThe CW radar operates using continuous wave transmission, while the FMCW radar employs frequency-modulated continuous wave technology. Range measurement is a crucial aspect of radar systems, providing information about the distance to a target. The IF amplifier plays a key role in signal processing, amplifying intermediate frequency signals for further analysis. The FMCW altimeter utilizes frequency-modulated continuous wave technology to accurately measure altitude above a reference point.
CW RADAR, FMCW RADAR, FMCW ALTIMETER, AND THEIR PARAMETERS
Hydrogen embrittlement
1. Hydrogen Embrittlement
Embrittlement is a phenomenon that causes loss of
ductility in a material, thus making it brittle. There are
a number of different forms including:
•Environmentally Induced Cracking.
•Stress Corrosion Cracking.
•Hydrogen Embrittlement.
•Corrosion Fatigue.
•Liquid Metal Embrittlement.
Of these, hydrogen embrittlement is responsible for a
surprising number of delayed failures and problems
with products produced from wire, especially if they
undergo secondary processing operations such as
plating. The factors (see Figure 1) responsible for this
type of failure include having a susceptible material,
an environment conductive to attack and the presence
of stress (internal or applied). Once two of these three
factors are present, failure is inevitable.
Hydrogen embrittlement is also known as hydrogen
induced cracking or hydrogen attack. Materials that
are most vulnerable include high-strength steels, ti-
tanium and aluminum alloys and electrolytic tough
pitch copper. Hydrogen embrittlement mechanisms
(see Figure 2) can be aqueous or gaseous and involve
the ingress of hydrogen into the metal, reducing its
ductility and load bearing capacity. Stress below the
yield stress of the susceptible material then causes
subsequent cracking and catastrophic brittle failures
(see Figure 3).
xx Wire Forming Technology International/Fall 2010
Although many of the most severe hydrogen
embrittlement problems have occurred in
aircraft applications, it should be remembered
“that it doesn’t have to fly in order to die”.
How Hydrogen Gets In
It is generally agreed that hydrogen, in atomic form,
will enter and diffuse through a metal surface whether
at elevated temperatures or ambient temperature.
Once absorbed, dissolved hydrogen may be present
either as atomic or molecular hydrogen or in combined
molecular form (e.g., methane). Since these molecules
are too large to diffuse through the metal, pressure
builds at crystallographic defects (dislocations and
vacancies) or discontinuities (voids, inclusion/matrix
interfaces) causing minute cracks to form. Whether this
absorbed hydrogen causes cracking or not is a complex
by:
Daniel H. Herring
“The Heat Treat Doctor”®
, President
The HERRING GROUP, Inc.
P.O. Box 884
Elmhurst, IL 60126-0884 USA
www.heat-treat-doctor.com
Fig. 2 — Hydrogen embrittlement mechanisms.
Fig. 1 — Factors contributing to
hydrogen embrittlement.
2. interaction of material strength, external stresses and
temperature.
Sources of hydrogen include heat treating atmos-
pheres, breakdown of organic lubricants, the steelmak-
ing process (e.g., electric arc melting of damp scrap),
the working environment, arc welding (with damp
electrodes), dissociation of high pressure hydrogen
gas and even grinding (in a wet environment).
Parts that are undergoing electrochemical surface treat-
ments such as etching, pickling, phosphate coating,
corrosion removal, paint stripping and electroplating
are especially susceptible. Of these, acid cleaning is the
most severe, followed by electroplating at high cur-
rent (these are less efficient and create more hydrogen
even though they produce a better plated structure),
electrolysis plating and conversion coatings.
Nature & Effect of Hydrogen Attack
Although the precise mechanism(s) is the subject of
active investigation, the reality is that components fail
due to this phenomenon. It is generally believed that
all steels above 30 HRC are vulnerable, as are materials
such as copper, whether tough pitch or oxygen-free,
titanium and titanium alloys, nickel and nickel alloys
and the like. Examples of hydrogen damage and ways
to avoid it include the following.
•Problem: Internal cracking or blistering.
Solutions: Use of steel with low levels of impuri-
ties (i.e., sulfur and phosphorus); modifying the
environment to reduce hydrogen charging; use of
surface coatings and effective inhibitors.
•Problem: Loss of ductility.
Solutions: Use of lower strength (hardness) or high
resistance alloys; careful selection of materials of
construction and plating systems; heat treatment
(bakeout) to remove absorbed hydrogen.
•Problem: High temperature hydrogen attack.
Solutions: Selection of material (for steels, use of
low and high alloy Cr-Mo steels, selected Cu alloys,
nonferrous alloys); limit temperature and partial
pressure H2.
Since a metallurgical interaction occurs between atomic
hydrogen and the crystallographic structure, the abil-
ity of the material to deform or stretch under load is
inhibited. Therefore, it becomes “brittle” under stress
or load. As a result, the metal will break or fracture at
a much lower load or stress than anticipated. It is this
lower breaking strength that makes hydrogen embrit-
tlement so detrimental.
In general, as the strength of the steel goes up, so
does its susceptibility to hydrogen embrittlement.
High-strength steel, such as quenched and tem-
pered steels or precipitation-hardened steels, is
Fall 2010/Wire Forming Technology International xx
particularly susceptible. Hydrogen embrittlement is
considered the Achilles heel of high strength ferrous
steels and alloys.
And nonferrous materials are not immune to attack.
Tough-pitch coppers and even oxygen-free coppers
are subject to a loss of (tensile) ductility when ex-
posed to reducing atmospheres. Bright annealing in
hydrogen bearing furnace atmospheres, oxy-acety-
lene torch brazing and furnace brazing are typical
processes that can create hydrogen embrittlement of
these materials.
The attack in these copper alloys involves the diffusion
of atomic hydrogen into the copper and subsequent
reduction of cuprous oxide (Cu2O) to produce water
vapor and pure copper. An embrittled copper often
can be identified by a characteristic surface blister-
ing resulting from expansion of water vapor in voids
near the surface. Purchasing oxygen-free copper is no
guarantee against the occurrence of hydrogen embrit-
tlement, but the degree of embrittlement will depend
on the amount of oxygen present.
For example, CDA 101 (oxygen-free electronic) allows
up to 5 ppm oxygen while CDA 102 (OFHC) permits
Fig. 3 — Hydrogen
embrittlement and
failure of a hard
chromium-plated
chain conveyor bolt.
Fig. 4 — Intergranular fracture due to hydrogen
embrittlement (photo courtesy of Aston
Metallurgical Services Co., Inc.).
3. xx Wire Forming Technology International/Fall 2010
Hydrogen Embrittlement ...continued
up to 10 ppm. A simple bend test is often used to
detect the presence of hydrogen embrittlement. Met-
allographic techniques (Figure 4) can also be used to
look at the near surface and for the presence of voids
at grain boundaries.
How Hydrogen Gets Out?
Hydrogen absorption need not be a permanent condi-
tion. If cracking does not occur and the environmental
conditions are changed so that no hydrogen is gener-
ated on the surface of the metal, the hydrogen can
re-diffuse out of the steel, and ductility is restored.
Performing an embrittlement relief, or hydrogen bake
out cycle (the term “bake-out” involves both diffusion
within the metal and outgassing) is a powerful method
in eliminating hydrogen before damage can occur.
Some of the key variables include temperature, time
at temperature, and concentration gradient (atom
movement).
For example, electroplating provides a source of hy-
drogen during the cleaning and pickling cycles, but by
far the most significant source is cathodic inefficiency.
A simple hydrogen bake out cycle can be performed to
reduce the risk of hydrogen damage (Table 1).
Caution: over-tempering or softening of the steel can
occur, especially on a carburized, or induction hard-
ened part.
Factors that Influence Hydrogen
Embrittlement on Parts
The severity and mode of the hydrogen damage de-
pends on:
•Source of hydrogen—external (gaseous)/internal
(dissolved).
•Exposure time.
•Temperature and pressure.
•Presence of solutions or solvents that may undergo
some reaction with metals (e.g., acidic solutions).
•Type of alloy and its production method.
•Amount of discontinuities in the metal.
•Treatment of exposed surfaces (barrier layers, e.g.,
oxide layers as hydrogen permeation barriers on
metals).
•Final treatment of the metal surface (e.g., galvanic
nickel plating).
•Method of heat treatment.
•Level of residual and applied stresses.
Low Hydrogen Concentrations
Can Also Be Problematic
Of concern today is embrittlement from very small
quantities of hydrogen where traditional loss-of-
ductility bend tests cannot detect the condition. This
atomic level embrittlement manifests itself at levels as
low as 10 ppm of hydrogen (in certain plating applica-
tions it has been reported that 1 ppm of hydrogen is
problematic).
Although difficult to comprehend, numerous
documented cases of embrittlement failures with
hydrogen levels this low are known. This type of
embrittlement occurs when hydrogen is concen-
trated or absorbed in certain areas of metallurgical
instability.
This type of concentrating action occurs as a result
of either residual or applied stress, which tends
to “sweep” through the atomic structure, moving
the infiltrated hydrogen atoms along with it. These
concentrated areas of atomic hydrogen can then
coalesce into molecular-type hydrogen, resulting in
the formation of highly localized partial pressures
of the actual gas.
What Type of Parts Are Susceptible?
Although almost any type of part is subject to hydro-
gen embrittlement, certain components such as fasten-
ers and nuclear components are most susceptible.
Ways to Avoid Hydrogen Embrittlement
Steps that can be taken to avoid hydrogen embrit-
tlement include reducing hydrogen exposure and
susceptibility, baking after plating (mandatory and as
soon as practical) and using test methods to determine
if a material is suspect.
Other options that could help in avoiding hydrogen
embrittlement include the use of lower strength
Table 1. Hydrogen Bake-Out Requirements
for High Strength Parts.
Note: Per ASTM B 850-98 (2009), Standard Guide for
Post-Coating Treatments of Steel for Reducing the Risk
of Hydrogen Embrittlement.
4. WFTI
steels (not always viable), the avoidance of acid
cleaning, the utilization of low hydrogen plating
techniques and the reduction of residual and ap-
plied stress.
Where to Go For Help?
A good, but relatively unknown source for information
about the effects of hydrogen, is the NACE Interna-
tional, The Corrosion Society (www.nace.org). Also,
various ASTM specifications (www.astm.org) can also
help, including ASTM B850-98, 2009 (Standard Guide
for Post-Coating Treatments of Steel for Reducing the
Risk of Hydrogen Embrittlement); ASTM F1113-97 (The
Barnacle Electrode Method to Determine Diffusible Hy-
drogen in Steels); ASTM F519-08 (Standard Test Method
for Mechanical Hydrogen Embrittlement Evaluation of
Plating/Coating Processes and Service Environments);
and ASTM F1624-09 (Standard Test Method for Meas-
urement of Hydrogen Embrittlement Threshold by the
Incremental Step Loading Technique).
The Bottom Line
Although many of the most severe problems associ-
ated with hydrogen embrittlement have occurred
with aircraft/aerospace parts, a simple motto to
remember is that the part doesn’t have to “fly” in
order to “die”.
The insidious nature of hydrogen embrittlement
continues to cause product failures during process-
ing and during service. These failures are often
catastrophic, leading to injury or damage to adjacent
structures, and are difficult to detect after the fact.
For this reason, hydrogen damage can and must be
avoided.
For additional information on dealing with hydro-
gen embrittlement, visit the website listed below.
www.heat-treat-doctor.com
References:
• Herring, D. H., and Richard D. Sisson, Jr., The Heat
Treatment of Fasteners – Embrittlement Issues, Fastener
Technology International, December 2008.
• Herring, D. H., The Embrittlement Phenomena in
Hardened & Tempered Steels, Industrial Heating,
October 2006.
• Herring, D. H., A Heat Treaters Guide to Hydrogen
Embrittlement, Industrial Heating, October 2004.
Fall 2010/Wire Forming Technology International xx