PNL QUALITY EXAMINER

Metallurgical/Materials engineering is a specialty area that studies metals, plastics, ceramics, and other composite materials which has developed from modern manufacturing practices. The primary focus is the composition and processing of metals and how that affects their performance under a variety of applications and environmental conditions. Understanding and proper application of metallurgical principles are critical to evaluating how metals perform in industry.

Our Metallurgical/Materials engineers provide failure analysis/forensic analysis, material characterization and quality control for a variety of industry sectors including construction, mining, semiconductor, manufacturing, medical devices, power generation, and critical tank, vessel, and piping assets. Our lab has experienced increases in client projects across all industry sectors over the last five years. 

Our metallurgical staff works with our nondestructive testing, welding, and physical/mechanical departments complementing each other to further investigate testing analyses, which exemplifies the concept of ‘where quality meets value.’

Our metallurgical facility features a variety of technologies, such as field emission scanning electron microscope (SEM, FeSem), energy dispersive X-ray spectroscopy (EDS), precision cross-sectioning, micro-hardness testing (Knoop and Vickers), superficial hardness, FTIR (both bulk and micro), positive material identification (PMI), IR Thermography, and lab and field services, which synchronizes with the other departments at PNL.

Additionally, we offer Fourier Transform Infrared Spectroscopy (FTIR) bulk and micro analysis capabilities as well as Infrared Thermography (IR).

FTIR allows for the analysis of a wide range of applications, especially related to polymeric and organic compounds. FTIR identifies fibers and contaminants for medical devices and analyzes plastics. The technique is widely used for identification in tandem with quality and process control. FTIR analysis allows PNL to offer a unique service not readily available in the Valley.

IR (infrared) thermography testing is a form of nondestructive, contact-less testing that measures temperature variances of a component as heat (i.e., thermal radiation) flows through, from, or to a component. Everything above absolute zero emits some amount of infrared radiation invisible to the naked eye. Infrared thermography captures the radiation, converts it into a temperature and displays a thermal image called a thermogram, which displays variations in temperature with different colors or shades of gray. This testing method can be used to evaluate structural and thermal conditions in electrical components, buildings, processing equipment and HVAC equipment.

Testing is performed per industry standards and in accordance with our ISO 17025 accreditation, including ASTM E3, ASTM E18, ASTM E384, ASTM E112, ASTM E10, ASTM A247, ASTM B487, ASTM B748, equivalent ISO standards, and applicable specialized procedures.

For more information regarding our Metallurgical/Materials lab capabilities contact Amber Trees, P.E. at: amber@pnltest.com

In 1863 an English geologist named Henry Clifton Sorby was the first to polish metal for microscopic inspection to correctly examine polished and chemically etched metal samples under the microscope. His father deeded him a cutting tool manufacturing shop in Sheffield, when Henry observed that cutting tools broke with a crystalline appearance like rocks. He suspected that, just like rocks, the microscopic features of metals might be revealed by polishing. He also suspected that, just like rocks, the properties of the metal might be correlated to the features revealed under the microscope. This coincidence turned out to be the most important discovery of modern metallurgy.

The internal microscopic features of materials are now called the “microstructure” of the material, and the microstructure correlates with properties better than any other material characteristic. 

To see the microstructure, a sample is taken through a process called "metallographic preparation." The intent of metallographic preparation is to accurately reveal the microstructure of the material.

Essentially, materials analysis involves identifying the chemical and structural composition of a material to understand its derived properties (e.g. optical and electrical properties, wettability, catalytic effect, solderability, roughness, color, etc.).

Positive material identification (PMI) is a term used in the industry and refers to analyzing various metal components to ensure the correct material, such as 304 or 316 stainless, is being utilized as part of client’s quality assurance/quality control programs. The most widely used technique for PMI testing is x-ray fluorescence (XRF) but small amounts of material can be analyzed with energy dispersive spectroscopy (EDS), used in conjunction with scanning electron microscopy (SEM).

Fourier Transform Infrared Spectroscopy (FTIR) allows for the analysis of a wide range of applications, especially related to polymeric and organic compounds, a technique widely used for identification in tandem with quality and process controls. In addition to bulk FTIR analysis, PNL offers micro FTIR (reflectance, transmission and micro-ATR), a unique service not readily available in the Valley.

Over time, Materials Science has evolved from Metallurgy. In the U.S., most Metallurgical programs have now broadened their scopes to become Materials Science and Engineering programs.

At PNL, our materials/metallurgical engineer provides a variety of services including forensic analysis/failure analysis, material characterization, field emission scanning electron microscopy (FeSEM), energy dispersive spectroscopy (EDS), micro-hardness testing (Knoop/Vickers), precision cross sectioning, optical microscopy with digital capture capability, positive material identification (PMI), FTIR (both bulk and micro), IR thermography, and lab and field services.

For more information on PNL’s Materials/Metallurgical lab capabilities contact Amber Trees, P.E. at: amber@pnltest.com.

Hardness measurements can be used in the field to verify in-situ conditions including proper welding techniques, heat treatment, or changes in physical properties due to stress or environmental exposure. PNL offers several methods and techniques that are used depending on the conditions and application.  The accuracy of each method is critically dependent on the surface condition of the part as well as the mass of the material. Thin materials are extremely difficult to measure hardness accurately.  Likewise, corroded or rough surfaces may yield inaccurate results. Other factors include indentation shape, load, and duration, testing temperature and environment, instrument calibration, testing alignment, and operator skill and technique.  All of these factors can result in measurements that may not be accurate.

PNL uses three main methods to determine hardness in the field:  Telebrineller impact method, Leeb Rebound method, and Ultrasonic Contact Impedance (UCI Method).  All of these methods require a certain level of operator skill and alignment to obtain good measurements.  Also, proper calibration will be required that is based on the expected hardness range of the materials to be measured.  Each method has different indenter shapes and load applications that should be considered prior to making measurements.  Typically, the method to be used will be determined by specification, client preference, or in consultation with an experienced metallurgist.

The next most important factor to consider is surface condition and preparation, which is the factor that is most problematic. The surface must be clean and smooth and most likely will need to be prepared by grinding and/or polishing.   For this step, the proper grinding/polishing tools must be utilized.  Steel material that has scale or other deposits present should be rough ground using a 60 or 80 grit abrasive disc to remove them. It is important to keep the surface from faceting even the slightest bit.  The grinding marks should be in the same direction across the area.  Next, using 120 grit disc grinding evenly and making the grind marks 90 degrees from the previous step, going in the same direction evenly.  Preparation to 120 grit is usually sufficient for the Telerbrineller and Leeb methods.  For more accurate Leeb measurements and for UCI measurements, continue to prepare the area in steps using 240 grit, 320 grit, and 400 grit grinding discs.  Roloc makes a nice 2" disc that works great for this application. Once the surface has been prepared to a smooth even condition with no faceting and grinding marks, all in the same direction, the surface should be wiped with a clean cloth to remove any dust or grinding grit.  Wiping with a cloth dampened with isopropyl alcohol is useful.  Once clean and dry, the surface is ready for measurement.

Using good technique and keeping the indenter/probe square to the part on a properly prepared surface will yield the best results and provide reliable, accurate test data.  To check accuracy, take two or three measurements in the same area.  Readings within 5% - 10% of each other indicate a good test.  Averaging the three readings is good practice and is the value typically reported as the hardness for that area.

Upon entrance to any worksite in the world, we expect to view a landscape of construction workers wearing hard hats. Historically, beginning with the industrial revolution, that was not always the case.

The hard hat concept comes from Bullard, a hundred-year-old, family-owned manufacturer of personal protective equipment who designed a basic hard-shell cap. Late in 19th century San Francisco, they began selling hard caps, carbide lamps and mining equipment to gold and copper miners.

A hundred years ago, the hard hat didn’t exist. And fifty years ago, head protection wasn’t widely required for workers. But, thanks to advances in safety, the hard hat has evolved over the decades, together with differing industry trends.  The latest trend in hard hats utilizes cutting edge head protection components used in extreme sports protecting your noggin from all sides including the top. The evolution of football helmets has progressed along similar lines beginning with leather in the 1930’s to today’s modern helmets made with viscoelastic foams.

The very first major construction project that required hard hats was the construction of the Hoover Dam in 1931. Hard hats were also required during the 1933 construction of the Golden Gate Bridge in San Francisco.

Hard hats are required when working in areas where there is a potential for injury to the head from falling objects. In addition, hard hats designed to reduce electrical shock are required when working near exposed electrical conductors that may contact the head.

Hard hats have a rigid shell that resists and deflects blows to the head. The suspension system inside the hard hat, which suspends the hard outer shell 1¼ inches from the user's head, acts as a shock absorber during impact and provides ventilation during wear.

The Occupational Safety and Health Administration (OSHA) head protection standards require that head protection should be provided and used whenever it is necessary by reason of hazard of processes or environment which could cause injury. The employer should determine which, if any, of its employees are exposed to the head injury hazards mentioned in the above standards and provide the necessary head protection.

Thus, it is the responsibility of the employer, prior to the OSHA inspection, to evaluate with good judgement the head injury hazards of the specific situations and activities in which the employees are involved and decide whether hard hats are needed to be worn.

PNL’s safety policy is that a technician on a job site always wear a hard hat, safety glasses and vest. PNL has recently purchased Studson non-vented hard hats and require they are worn at all times working on construction project sites. The Studson helmet has a brim and a strap snugly affixed to the head- the current style is marked by a brim and strapped hat.

Welding Procedure Specifications are required to be prepared and qualified in accordance with welding and fabrication codes including AWS D1 codes, ASME IX for pressure applications, API 650 for tanks, API 1104 for pipelines, and a variety of US Defense based specifications.  In order to determine how best to join materials by welding, it is imperative to know the material specification, chemical makeup, and tensile properties of each material to be joined.  This is most often accomplished by reviewing mill certifications provided by the material suppliers at the time the material was purchased.  Mill certifications will list the material specification and give both chemical and tensile properties of the materials listed.

The primary reason for this is to determine the filler material and electrodes that are best matched to the base materials.  Base material and filler metal are both essential variables that are to be listed on the WPS. Other essential variables are also required to be listed on the WPS, but are mostly related to the welding process, base material, and filler metals to be used.  For example, preheat and post-weld heat treatment, also essential variables, are dependent on the material specification and thickness.

However, there are times when the mill certifications are not available and the material is unknown. It may be that the mill certification has been lost, or the markings on the material have been removed or are no longer traceable back to the mill cert.  In these cases there needs to be some way to determine what the materials are.  We can start to narrow down the materials by first determining if the metal is magnetic or non-magnetic by using a simple magnet.  But this does not provide the chemical or tensile properties required.  For steels, an acceptable method would be to sample the material and provide chemical analysis in accordance with ASTM A6 and physical property tests in accordance with ASTM A370.  For ASTM A6 several methods for determining chemical analysis are allowed including OES and X-ray fluorescence, which can be provided nondestructively by some laboratories.  API 650 for welded steel tanks also requires that carbon and manganese be determined regardless of the material specification requirements.  Tensile tests would then need to made on material removed from stock, which can be provided by most any material testing laboratory.

Alternatively, the WPS can be qualified by welding samples of unknown materials and performing the required tests.  Usually, this requires that samples be cut out of the existing materials.  In the case of in-service components, this may be inconvenient or not be possible.  In some cases this will be mandatory.  API 653, for example, requires that new material being welded to existing tank material that is not identified be qualified using a section of existing tank.  If the WPS is qualified on the unknown materials, it is only valid for that specific material, unless the chemical analysis and tensile properties are performed.

We are excited to announce that we are hosting an Open House at our new Tempe, Arizona facility on Friday July 26th from 3 PM to 7 PM. The address is 941 S. Park Lane Tempe Arizona 85281. Refreshments and light snacks will be served. Our clients, prospective clients, vendors, and related associates are invited to the event which is also open to the public. Guided tours will be led by PNL technicians and managers who will showcase our capabilities and resources. The open house will include a Ribbon Cutting event by the Tempe Chamber of Commerce.

PNL is a 3rd party quality testing, inspection, and engineering services provider, that opened its doors in 1994. We offer both field and laboratory services to clients in the construction, manufacturing, fabrication, medical device, semiconductor, mining, power generation, transportation, and petrochemical industries The recent move will display its upgraded 38,000 square feet ISO 17025:2107 certified lab, which houses physical, mechanical, materials/metallurgical and nondestructive testing services.

As we celebrate our new Tempe, AZ building on Park Lane, we are inspired by the irony that “it took 30 years to cross the street.” PNL opened its doors in 1994 at 940 S. Park Lane, in a modest single industrial park suite directly across the street from our current address.