One Minute Mentor: Fatigue Testing of 316 Stainless Steel Round Bar
November 13, 2017 Source: ASM International
The graph shows the results of fatigue testing of standard round bar 316 stainless steel specimens, in tension-compression cycling (R = –1) The symbols represent different sets of specimens, with nontreated specimens identified by triangles, treated specimens by squares.
Continue readingOne Minute Mentor: Time-Temperature-Transformation Diagram
October 31, 2017 Source: ASM International
Traditionally, carburization is carried out at high temperature to maximize the solubility and the rate of interstitial solute diffusion.
Continue readingOne Minute Mentor: Variations in Heat-Treating Cycles of PH Stainless Steels
October 31, 2016 Source:
One of the principal advantages of these materials is their versatility. Although certain heat treatments are classified as standard, there are applications where deviations from these standards are desirable.
The graphs show the effect of variations in annealing temperature on typical mechanical properties of 17-7 PH sheet, strip, and plate.
Heat Treating of Precipitation-Hardenable Stainless Steels and Iron-Base Superalloys ⇒ Heat Treated High-Alloy Steels ⇒ Heat Treating of Martensitic Stainless Steels ⇒ General Procedures
One of the principal advantages of these materials is their versatility.
Continue readingOne Minute Mentor: Heat Treating of Martensitic Stainless Steels
October 10, 2016 Source:
The effect of tempering temperature on hardness and tensile properties of high-alloy steels appears to have the same general form as those of low-alloy steel. A serious decrease in notch toughness occurs when tempering between about 750 and 950°F, as illustrated in the graph for Type 410.
The graph shows the effect of tempering temperature on impact properties of AISI Type 410. Impact energy tests used Izod, Charpy V-notch, or Charpy keyhole as indicated. Heat treatment of test specimens: heated to and held at 1750°C for one hour; oil quenched, temperad for four hours at temperature given; air cooled.
Volume 4D, Heat Treating of Irons and Steels ⇒ Heat Treated High-Alloy Steels ⇒ Heat Treating of Martensitic Stainless Steels ⇒ Tempering
The effect of tempering temperature on hardness and tensile properties of high-alloy steels appears to have the same general form as those of low-alloy steel.
Continue readingChromium Nitride in Duplex Stainless Steels
September 9, 2016 Source:
Because of the use of nitrogen as an alloying element in these stainless steels, chromium nitrides (CrN) may be present on α/α grain boundaries, on γ/α boundaries, and within the α grains. If formed in large quantities and under conditions in which the chromium-depleted areas do not have time to repair themselves during annealing, the presence of CrN may adversely affect corrosion resistance.
However, because higher nitrogen promotes more γ- phase, which has a high solubility for nitrogen, most modern DSS steels seldom contain significant amounts of CrN. Furthermore, duplex stainless steels are made with very low carbon content, so that carbide formation to a detrimental extent is not usually a concern. The only exceptions to this are the very lean grades, such as S32101, S32022, and S82011, which can lose corrosion resistance and toughness due to carbide and nitride formation. This is most likely to occur in the 1130 to 1475°F range.
With these very lean grades, the rate of formation of intermetallic compounds is sufficiently slow that the phases most likely to cause a loss of properties are the carbides and nitrides. The kinetics of carbide and nitride formation is similar to that of σ/χ precipitation in the 2205 grade.
Volume 4D, Heat Treating of Irons and Steels ⇒ Heat Treated High-Alloy Steels ⇒ Heat Treating of Austenitic and Duplex Stainless Steels ⇒ Duplex Stainless Steels
Because of the use of nitrogen as an alloying element in these stainless steels, chromium nitrides (CrN) may be present on ?/? grain boundaries, on ?/? boundaries, and within the ? grains. If formed in large quantities and under conditions in which the chromium-depleted areas do not have time to repair themselves during annealing, the presence of CrN may adversely affect corrosion resistance.
Continue readingOne Minute Mentor: Precipitation of Intermetallics in Stainless Steels
August 29, 2016 Source: ASM International
The exposure of duplex stainless steels to temperatures in the range of 1100 to 1850°F can result in the formation of undesirable intermetallic compounds such as σ and χ phases.
Continue readingOne Minute Mentor: Effects of Different Cooling Rates on Corrosion-Resistant Tool Steels
March 18, 2016 Source:
The graph shows the effects of different cooling rates on the toughness properties (un-notched samples) of AISI 420 and nitrogen-alloyed M333 tool steels.
The cooling parameter λ8/5, which is the cooling time from 1470° to 930°F in seconds, divided by 100, is used. Besides the general trend of falling toughness with rising cooling time, it is clearly evident that the nitrogen-alloyed steel grade M333 (420Mod), which has a lower carbon content, shows significantly higher toughness values. These can be further improved by lowering the austenitizing temperature. This behavior correlates well with the reduced tendency to form proeutectoid carbides at grain boundaries. A similar correlation can be found for the steel grades AISI 440B and the nitrogen-alloyed M340 (440Mod).
Volume 4D, Heat Treating of Irons and Steels ⇒ Tool Steels ⇒ Heat Treating of Mold Steels and Corrosion-Resistant Tool Steels ⇒ Recommended Heat Treating Practices
The graph shows the effects of different cooling rates on the toughness properties (un-notched samples) of AISI 420 and nitrogen-alloyed M333 tool steels.
Continue readingOne Minute Mentor: Secondary Hardening in Tool Steels
January 22, 2016 Source:
As shown schematically in the graph, high-temperature hardness is made possible only by a very important straightening mechanism: secondary hardening, promoted by the precipitation of fine alloy carbides. The stronger the secondary hardening (meaning more intense carbide precipitation), the higher the tempering resistance of hot-work tool steels. Such precipitation intensity depends on the amount of alloy elements in solid solution, which is related to the alloy composition and heat treating practice obtained by molybdenum, vanadium, or tungsten alloying.
The graph shows a schematic of hardness after tempering and the effect of secondary hardening in high-alloy steels. Observe that high-temperature hardness is only possible through precipitation hardening caused by alloy carbides (secondary hardening). At low temperatures, hardness is less than martensite due to the presence of retained austenite, which is eliminated after high-temperature tempering.
Volume 4D, Heat Treating of Irons and Steels ⇒ Tool Steels ⇒ Heat Treating of Hot-Work Tool Steels ⇒ Introduction
As shown schematically in the graph, high-temperature hardness is made possible only by a very important straightening mechanism: secondary hardening, promoted by the precipitation of fine alloy carbides.
Continue readingOne Minute Mentor: Austenitizing Water-Hardening Tool Steels
November 30, 2015 Source:
Austenitizing temperatures for water-hardening tool steels normally vary from 1400 to 1550°F. Higher temperatures are sometimes used for special purposes. Hardenability increases as austenitizing temperature increases. The optimum time at austenitizing temperature is from 10 to 30 minutes. Preheating is unusual except for very large tools or those with intricate cross sections.
The graph shows the maximum section thicknesses of three classes of water-hardening tool steels that develop minimum hardness of 60 HRC when oil quenched from various austenitizing temperatures.
It is particularly important to protect shallow-hardening steels against scaling and decarburization. Severe scaling can interfere with heat transfer during quenching and slow the required high rate of cooling. Decarburization will produce a soft surface on any tool steel, but in a deep-hardening steel it can be ground off until the underlying hard high-carbon area is reached. Grinding a shallow-hardening steel will frequently expose the soft core.
Volume 4D, Heat Treating of Irons and Steels -> Tool steels -> Introduction to Heat Treating of Tool Steels -> Water Hardening Tool Steels
Austenitizing temperatures for water-hardening tool steels normally vary from 1400 to 1550°F. Higher temperatures are sometimes used for special purposes.
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