Understanding the Benefits of Austempering

Austempered ASI 1055 - 768 BLOG

“Austempering is essentially an arrested quench process designed to produce a bainitic microstructure having properties that combine high hardness with toughness, resulting in a resistance to brittle fatigue.” –Daniel Herring, Industrial Heating Magazine.  (Photo of Austempered ASI 1055)

———— ::: ————

For over forty years we here at Kowalski Heat Treating have been recommending austempering as the perfect solution to many of our customer’s PIA (pain in the @#$) jobs. More often than not, it’s the ideal distortion management solution for specialty jobs such as shafts, pins, saw blades, pistons, flat plates, brake discs, clutch parts, large stampings and other sensitive work requiring high hardness, longer-lasting toughness and increased strength.

Our K-Salt Division, the largest rack salt-to-salt facility in the Midwest, enables us to better control the cooling rate of crack sensitive steels and other alloys. Some of the benefits to our customers include:

• Our custom design fixturing team can quickly and efficiently implement new fixtures to maintain your tight tolerances while achieving the optimum heat treating cycle possible.

• Whether custom specialty distortion-free austempering treatments or higher volume marquenching batch work, our system engineers can help reduce tool-up times and fixture down times, giving you an edge in reducing costs and shortening your production run times.

• We can process up to 50,000 pounds per day, including “PIA” rack jobs or parts up to 36” in diameter and/or 40″ long.

• Austempering is ideal for Automotive, Power Transmission, Construction Equipment, Heavy Industry, Truck & Bus, Distortion Sensitive Forgings, ADI Processing, Government & DOD, FCC Licensed Guns/Firearms, Mining & Off Road Parts, Mower Blades, Outdoor Power Equipment, Stampings and Tool & Die jobs.

To better understand the benefits of Austempering, I went back to one of my favorite articles on the subject (originally published in 2005) and contacted “The Heat Treat Doctor” Daniel Herring, from Industrial Heating magazine. We got his “ok” along with the publishers of Industrial Heating magazine to repost part of his article. Read the full article HERE.

Enjoy – (and call me about your pesky PIA Jobs – we’re ready to help!!)

 

 

 

 

What’s In A Name?

AISI/SAE Steel Designations

Have you ever wondered how plain carbon and alloy grades are named? You can actually know how much carbon and what alloys are in the material by just knowing the designation.

Materials are designated by a four digit number, where

  1. the first digit indicates the main alloying element(s)
  2. the second digit indicates the secondary alloying element(s)
  3. the last two digits of these indicates the carbon content (hundredths of a percent)
    (example, in Grade 1045 the 45 indicates a nominal carbon content of 0.45 wt% C)

Here is the naming system used to determine the steel designations: Enjoy.

 

GRADE      TYPE OF STEEL & NOMINAL ALLOY CONTENT, %          

Carbon Steels

10XX               Plain carbon (Mn 1.00 max.)
11XX               Resulfurized
12XX               Resulfurized and rephosphorized
15XX               Plain carbon (max Mn range; 1.00-1.65)

 

Manganese Steels

13XX               Mn 1.75

 

Nickel Steels

23XX               Ni 3.50
25XX               Ni 5.00

 

Nickel-Chromium Steels

31XX               Ni 1.25; Cr 0.65 and 0.80
32XX               Ni 1.75; Cr 1.07
33XX               Ni 3.50; Cr 1.50 and 1.57
34XX               Ni 3.00; Cr 0.77

 

Molybdenum Steels

40XX               Mo 0.20 and 0.25
44XX               Mo 0.40 and 0.25

 

Chromium-Molybdenum Steels

41XX               Cr 0.50, 0.80, and 0.95;
Mo 0.12, 0.20, 0.25, and 0.30

 

Nickel-Chromium-Molybdenum Steels

43XX               Ni 1.82; Cr 0.50 and 0.80; Mo 0.25
43BVXX           Ni 1.82; Cr 0.50; Mo 0.12 and 0.25; V 0.03 min
47XX               Ni 1.05; Cr 0.45; Mo 0.20 and 0.35
81XX               Ni 0.30; Cr 0.40; Mo 0.12
86XX               Ni 0.55; Cr 0.50; Mo 0.20
87XX               Ni 0.55; Cr 0.50; Mo 0.25
88XX               Ni 0.55; Cr 0.50; Mo 0.35
93XX               Ni 3.25; Cr 1.20; Mo 0.12
94XX               Ni 0.45; Cr 0.40; Mo 0.12
97XX               Ni 0.55; Cr 0.20; Mo 0.20
98XX               Ni 1.00; Cr 0.80, Mo 0.25

 

Nickel-Molybdenum Steels

46XX               Ni 0.85 and 1.82; Mo 0.20 and 0.25
48XX               Ni 3.50; Mo 0.25

 

Chromium Steels

50XX               Cr 0.27, 0.40, 0.50, and 0.65
51XX               Cr 0.80, 0.87, 0.92, 0.95,1.00, and 1.05

 

Chromium (Bearing) Steels

50XXX             Cr 0.50
51XXX             Cr 1.02 C 1.00 min.
52XXX             Cr 1.45

 

Chromium-Vanadium Steels

61XX               Cr 0.60, 0.80, and 0.95; V 0.10 and 0.15 min

 

Tungsten-Chromium Steels

72XX               W 1.75; Cr 0.75

 

Silicon-Manganese Steels

92XX               Si 1.40 and 2.00; Mn 0.65, 0.82, and 0.85; Cr 0 and 0.65

 

High-Strength Low-Alloy Steels

9XX                  Various SAE grades

 

Boron Steels

XXBXX              B denotes boron steel

 

Leaded Steels

XXLXX              L denotes leaded steel

 


 

Win-Win at Heat Treat 2015

Meet up with the Kowalski folks at HEAT TREAT 2015 and maybe win a new iPad Air!
Details below. Hope to see you in Detroit!

KHT October Ad 768

 


  view history .

A Toast to Charles Strite!

toaster art 768 blog

As you know, heat treating is near and dear to our hearts here at KHT. Everyday we strive to “make history” with our efficiency, consistency, performance and reliability, never taking for granted any one of our customers or customer’s jobs.

Well, nearly 100 years ago, a gentleman named Charles Strite also contributed to heat treating history, by patenting something we’ve come to rely on each morning – the pop-up toaster. (Filed for U.S. patent on May 29, 1919. Patent #1,394,450 was granted on October 18, 1921 for the pop-up bread toaster)

He hated that the toast in the cafeteria of the plant where he worked was always burned because it required a busy human to keep an eye on it. So he took on this PIA (Pain in the @%$) Job and figured out a way to automate the toasting process so it wouldn’t burn.

Before the electric toaster, sliced bread was toasted by placing it in a metal frame or on a toasting fork and held over a fire or kitchen grill. The first electric toaster was actually invented in Scotland in 1893. It was a crude device known as the Eclipse. It still relied on users to end the toasting process and was not very fire safe.

So, while some tried to flip the bread, it was Mr. Strite who invented the automatic pop-up toaster. History shows many innovations since – dual sided toasting, wider slots, auto-drop feeds, and numerous interior and exterior material innovations.

This weekend, make yourself some toast and thank crafty Mr. Strite for tackeling this PIA (Pain in the @%$) Job. Oh, and try one of my favorite toppings – honey. Yum!

—Steve

 


 

Tech it out!

certificate 560 email

We are proud to announce our continued ISO 9001 Certification. Each and every one of us at KHT values your business and we hope you understand that this certification represents our dedication to you within every process, procedure and action we take.

Here are the eight main business principles we strive to exceed:

• Customer focus
• Leadership
• Involvement of people
• Process approach
• System approach to management
• Continual improvement
• Factual approach to decision making
• Mutually beneficial supplier relationships

We want you to know that it’s not just about performing tasks to conform to the ISO 9001. It’s about performing every task for the mutual good of our businesses. Yours and ours. Simply put, it’s a culture thing here at KHT. It’s what we do. It’s who we are.

— Steve

 


 

Hardness vs. Strength and a Salute to Rockwell

Rockwell 1914 Patent LR

The relationship of hardness and strength is common in the distortion sensitive thermal processing jobs here at Kowalski Heat Treating, where we’re always trying to solve customer part performance requirements, especially their PIA (Pain in the @%$) Jobs!

For some of our customers, the words hardness and strength are often used interchangeably. However, when used as metallurgical terms to describe properties, the meanings are different and in some cases may even be complete opposites.

The strength of a material is directly related to the hardness and is independent of the grade. For example, if you have S7 at 48 HRC and H13 at 48 HRC they will have similar ultimate tensile strengths. The yield strength which is the stress that begins to cause permanent deformation is going to be approximately 80-95% of the tensile strength for the most tool steels. A less ductile material will have its yield strength closer to its tensile strength due to the lack of elongation and reduction of area during the tensile test. The relationship to hardness and tensile strength can be found in heat treat or mechanical strength reference books.

For us, the challenge is the delicate balance of hardness and strength, and the need to be consistent piece after piece, load after load, and delivery after delivery – the “magic and value” behind KHT Heat.

About 100 years ago, Stanley Rockwell, born in New Britain, CT in 1886, worked as a testing engineer and metallurgist for the New Departure manufacturing company in Bristol, CT., making ball bearings, automobiles and its best known product, the coaster bicycle brake some of us used when we were kids. While at the company, Stanley worked with Hugh Rockwell (no relation) an avid aviator and automobile enthusiast. The two spent a lot of their time trying to determine the best and most efficient way to measure the hardness of bearing races. The only tests at the time were Vickers (time consuming), Brinell (slow and not suitable for curved surfaces or small parts), Scleroscope (ok for hardened bearing steel but cumbersome to use) and the file test (useful only as a go/no go test at best).

To satisfy their needs, Stanley and Hugh invented the Rockwell Hardness Tester method, a simple sequence of major and minor load testing, enabling the user to perform an accurate hardness test on a variety of different sized parts in just a few seconds. The process proved to be useful, and in 1914 they filed for a patent (granted on February 11, 1919 after the Rockwell’s had left the company).

In the original patent application, they wrote: “We have devised a hardness tester which can be used by the ordinary workman to rapidly and accurately test the hardness not only of flat surfaces but also of raceways and other curved surfaced bodies.”

After leaving New Departure during WW1, Stanley served as a captain in the Army ordinance department and after the war became the works manager and metallurgist of the Weeks and Hoffman Co. in Syracuse, NY, where he improved the tester and applied for a second patent in Sept 1919. In 1923, he opened his own business called the New England Heat Treating Service Company – the name was later changed to the Stanley P. Rockwell Company in and still exists today.

Today, Rockwell Testing remains the most efficient and widely used hardness test thanks to the insights and efforts of Hugh and Stanley Rockwell, creative engineers always looking for practical solutions to problems.

 


 

HARDENING OF ALLOY AND TOOL STEELS FOR IMPROVED PERFORMANCE

At Kowalski Heat Treating (khtheat.com), we’re constantly working on behalf of our customers to achieve the proper balance of strength, durability and end performance when processing alloy and tool steels. This heat treatment process consists of heating and cooling these steels to move atoms to an atomic state called martensite.

The atomic arrangement of steels vary depending on the structure or phase it is in. Controlled heat treatment changes the arrangement of these atoms resulting in a desired hardness and mechanical properties specified by our customers. Often we customize this process to enhance tool life and durability.

“Tool steels are typically annealed after rolling or forming to make them suitable for machining and other operations, a process which consists of heating the steel slowly and uniformly to a temperature above the transformation range,” says Dave Lorenz, VP of Operations / Metallurgist at Kowalski Heat Treating. “The transformation range is the temperature at which the steel starts to form austenite, usually around 1350°F (the annealing temperature is 1600-1700°F). A slow cooling rate (25 – 40°F/hour maximum) from this temperature enables the alloys, in combination with the iron atoms, to form uniformly dispersed spheroidized carbides in a matrix of ferrite. This ferrite structure is a body-centered cubic structure (see graphic), typically the condition in which we receive steel tool grades unless they are pre-hardened by the customer.”

“To achieve the next phase, the tool steel is hardened by bringing the material up to its austenitizing temperature, which will range from 1500 – 2250°F depending on the grade,” said Dave. “Upon going through this transformation temperature range, the structure changes again – from ferrite to austenite. This austenite atomic structure is a face-centered cubic (see graphic) – a high temperature phase only formed by heating the tool steel to the appropriate temperature. Austenite is non-magnetic and is slightly denser than ferrite, causing the steel to shrink slightly when at this stage in heat treatment.”

“Upon cooling or quenching from the austenitizing temperature, the steel is transformed once again into a new atomic arrangement called martensite. The steel must be cooled fast enough to keep the dissolved alloy content in the matrix of the steel. The martensite is in the form of a body centered tetragonal structure (see chart) – the desired structure that most of our tool steels are in to achieve high hardness and strength properties. This arrangement of atoms is less dense which results in an overall growth after the quench and subsequent tempers.”

Once completed, the tool steel is shipped back to customers to be machined or sharpened for superior performance.

For more information on tool steel processing, contact Kowalski Heat Treating (khtheat.com) – the leader in distortion sensitive thermal processing, celebrating 40 years of excellence and customer service.

 


 

KHT is 40 This Year! Still Focused On Your PIA Jobs.

Kowalski Heat Treating was established in 1975 to specialize in Distortion Sensitive Thermal Processing, or in the words of our founder PIA (Pain In The @%$) Jobs!

Our dimensional management divisions and teams of specialists can help you save time and money, revitalize underperforming materials, reduce waste and scrap and provide confidence you are working with a reliable, dedicated partner.

We love and want your PIA (Pain In The @%$) Jobs!, your high volume, consistent critical jobs or your “one-off” hard to solve prototypes.  No matter. Our divisions are built to provide world-class specialized solutions for our customers, leveraging forty years of thermal processing excellence, backed by our commitment to quality, customer service, family and community.

To learn more, visit each of our specialty divisions HERE, or just call us at 1 888-KHT-HEAT (548-4328) or 216-631-4411.

New Plaque 723x462