For example, highcarbon and alloy steels with high hardenability often. The objective is to quench sufficiently fast to avoid undesirable concentration of the alloying elements in the defect and grain boundary structure while at the same time not quenching faster than necessary to minimize residual stresses, which may lead to excessive distortion or cracking. How to quenching and tempering of 4140 alloy steel. Analysis of quenching parameters in aisi 4340 steel by. Aisi 4340 steel is a medium carbon, low alloy steel known for its toughness and strength in relatively large sections. Cracked 4340 after quench metal and metallurgy engineering. Overheating during the austenitizing portion of the heat treatment cycle can coarsen normally fine grained steels. Six pieces of bar stock for each of the four grades of oil hardening steel 01 tool steel, 4140, 4150, and 4340 alloy steels were used for this test. Commercial and military aircraft, automotive systems, forged hydraulic and other machine tool applications, forged steel crankshafts.
Polymer quenching is particularly useful for quenching high integrity alloy steel forgings that require impact testing. Mar 28, 2012 certain highhardenability materials, such as 4340, are particularly prone to quench cracking and must be tempered immediately usually within 15 minutes of quenching to avoid problems. The quenchandtemper process induces enormous stresses, which can lead to part cracking during the process if good part design guidelines and proper heat treating practices are not followed. This is to reduce likelihood of cracking during quench.
Here are 7 ways that steel can fail as a result of quench cracking from heat treatment. This location was a highly stressed area and the location of a large mechanical stressconcentration factor because ofthe weld toe undercut. There is some evidence to suggest that high purity i. Polymer quenching is useful for a wide range of steels. Oil quenching is a common method for hardening alloy steel forgings. Except for plain carbon steels that are micro alloyed with just vanadium, niobium, andor titanium, most lowalloy steels are suitable as engineering quenched and tempered steels and are generally heat treated for. Quench cracks do not have decarburization apparent, since the. Inservice d2 toolsteel component failure due to quench cracking photograph. Overviewofthemechanismsoffailure in heat treated steel. However, as in motor shaft applications, under quenching and tempering conditions, 4340 steel typically use high preheating in low hydrogen processes.
Aisi 4340 steel stockholders and suppliers, delivering to the whole of the uk. An investigation into the mechanisms of tempered martensite embrittlement tme, also know as 500 or 350 or onestep temper embrittlement, has been made in commercial, ultrahigh strength 4340 and simodified 4340 300m alloy steels. Overviewofthemechanismsoffailure in heat treated steel components. The crack is seen to travel along the prior austenite grain boundaries. Throughhardening low alloy steel bar 4340 colour code. There has been no reported instance of quench cracking in the tooling grade 7010 grade z which has less restrictions on the combined fesi content. Aisi 4340 steel is a medium carbon, low alloy steel. Quenched and tempered lowalloy steel total materia article. I have some shafts to machine from 4340 512 dia stock, to an average size of 5. Aisi 4340 is a nickel chromium molybdenum alloy steel specification widely used in the oil and gas sectors.
Investigating the mechanisms that cause quench cracking in. Aisi 4340 alloy steel aisi 4340 steel stockholders and suppliers, delivering to the whole of the uk. Sae aisi 4340 steel properties, heat treatment, equivalent. Hardened and tempered 4340 alloy steel can also be nitrided, giving a surface hardness of up to rc 60. Heres a clip of an aggressive heat treatquenching process designed to allow maximum strength and hardness from this 4340 nickel alloy. Welding is not recommended because of the danger of quench cracking. It is ideal for achieving the required strength and hardness properties on many alloys.
It has the highest strength compared to the other variants of saeaisi 4140 steel. Evaluation of toughness in aisi 4340 alloy steel austenitized at low. From aisi 1045 to aisi 4340 the polymer quenching hardening heat treatment can be the solution for complex jobs. A quench and temper steel alloy is disclosed having the following composition in weight percent. Quenched and tempered saeaisi 4140 is saeaisi 4140 steel in the quenched and tempered condition. Oct 14, 20 heres a clip of an aggressive heat treatquenching process designed to allow maximum strength and hardness from this 4340 nickel alloy.
Analysis of quenching parameters in aisi 4340 steel by using. Here are seven ways that steel can fail as a result of quench cracking from heat treatment. It has been reported for asquenched aisi 4340 steel that high temperature austenitizing. Defects and distortion in heattreated parts asm international. This type of 4340 is also known for its elongation and. Its selection depends on the hardenability of the alloy and the. Pdf effect of quenching and tempering treatments on impact. Aisi 4340 steel, oil quenched 855c 1570f, 230c 450f. Quench cracks 3 ways to recognize speaking of precision blog. It has been reported for asquenched aisi 4340 steel that high temperature austenitizing treatments at 1200 instead of conventional heattreatment at 870 result in a two fold increase in fracture toughness, ktc, but a decease in charpy impact energy. Pdf analysis of quenching parameters in aisi 4340 steel by.
The lowalloy steels are those steels containing alloy elements, including carbon, up to a total alloy content of about 8. Aisisae 4340 alloy steel, 4340, is a nickelchromiummolybdenum alloy steel known for its toughness and its ability to attain high strengths in the heattreated condition. The following table shows the chemical composition of aisi 4340 alloy steel. Aisi 4340 alloy steel is a heat treatable and low alloy steel containing chromium, nickel and molybdenum. Quench cracks 3 ways to recognize quench cracks result from stresses produced during the transition from austenite to martensite, which involves an increase in volume. Alloy description timkensteels 4140hw grade is a finegrained, lowalloy steel that offers optimum heattreat response in heavier crosssections. Any condition that concentrates the stresses encountered in quenching will promote the formation of quench cracks e. Quench cracks run from the surface towards the center of mass in a fairly straight line. Atlas 4340 lowalloy steel bar complies with grade as1444, grade 4340 andor. Parts can therefore be machined to near final size, leaving a grinding allowance only. Normal ranges of mechanical properties corresponding to a specific hardness are listed below. Aisi 4340 is also one kind of nickel chromium molybdenum steels. Us20170002447a1 quench and temper corrosion resistant steel. This includes sharp changes of section, lack of radii, holes, sharp keyways, unbalanced sectional mass and other stress risers.
Following forging operation the work piece should be cooled as slowly as. While large 4140 rounds can be waterquenched, squares are a different story. Throughhardening low alloy steel bar 4340 atlas steels. If the use of water as quenching medium, 4140 steel cooling speed is faster at high temperature range, but the cooling speed is slow at low temperature range lower than the. Temper as soon as the steel reaches room temperature. Magnetic particle inspection is useful for ferrous alloys. Pre hardened and tempered 4340 can be further surface hardened by flame or. Quench cracking occurs when the material is unable to accommodate the plastic strains that result from the differential thermal contraction during quenching. Quench cracking promoted by nonmetallic inclusions in aisi 4140 steel heat treatment defects quench cracks heat treatment defects quenched from an excessively high temperature tool steels fractography heat treatment defects. Aisisae 4340 alloy steel 4340 steel properties all metals. The martensitic transformation starts at the outermost surfaces of the part being quenched.
Us20170002447a1 quench and temper corrosion resistant. Material and process selection can contribute to cracking as well. Chemical composition has been found to influence the propensity to quench crack with a high purity low iron and silicon version alloys demonstrating the greatest susceptibility. Overload failure of a quenchcracked aisi 4340 steel threaded. Mechanisms of tempered martensite embrittlement in low. The coarse austenite grain size may promote quenching cracks and increase. According to the actual production situation, we believe that the main reason of quenching crack of 4140 steel plate is. Preheat the steel 4340 first, heat up to 1150c 1200c maximum for forging, hold until temperature is uniform throughout the section. Quench cracks result from stresses produced during the transition from austenite to martensite, which involves an increase in volume. The physical properties of aisi 4340 alloy steel are. What happens to the physical size of 4340 during heat treating. Aisisae 4340 alloy steel 4340 steel properties all. Avoid over heating and overly long dwell times while austenitizing. Us20170002447a1 us15235,226 us201615235226a us2017002447a1 us 20170002447 a1 us20170002447 a1 us 20170002447a1 us 201615235226 a us201615235226 a us 201615235226a us 2017002447 a1 us2017002447 a1 us 2017002447a1 authority us united states prior art keywords alloy set forth contains steel up prior art date 20121024 legal status the legal status is an.
The high hardness of 4340 alloy steel requires that the material be welded in the annealed or tempered state and then heat treated to resist martensite formation and cold cracking. An aisi 4340 threaded steel connecting rod that was part of a connecting linkage used between a parachute and an instrumented drop test assembly frac. In the quenching action, the steel is subject to nonuniform cooling, thermal deformation, and a phased grain transformation that can literally pull the. Coarsely grained steels increase hardening depth and are more prone to quench cracking than fine grain steels. And it is used for making important quality controlling parts with good toughness, high strength, and large size, such as heavy machinery and high load shafts, dia of turbine shafts is larger than 250mm, helicopter rotor shafts, turbojet turbine shafts, blades, highload. Heat to 500c 530c and hold for sufficient time from 10 to 60 hours to develop the depth of the case.
The quench andtemper process induces enormous stresses, which can lead to part cracking during the process if good part design guidelines and proper heat treating practices are not followed. If quench uniformity is required, such as in complying with the caterpillar 1e0106a or 1e0106b specification, polymer quenching. Aisi 4340 has a favorable response to heat treatment usually oil quenching followed by tempering and exhibits a good combination of ductility and strength when treated thusly. It has high toughness and strength in the heat treated condition.
The quenched and tempered of 4140 alloy steel production process. When you oil quench steel forgings, theres also less risk of cracking compared to water quenching or polymer quenching. This is due to the very high hardenability which causes a severe volume change gradient going from austenite to martensite through the thickness. The 800 600 400 200 30 oil 60 90 time, s 120 150 o fig. The objective is to quench sufficiently fast to avoid undesirable concentration of the alloying elements in the defect and grain boundary structure while at the same time not quenching faster than necessary to minimize residual stresses, which. Certain highhardenability materials, such as 4340, are particularly prone to quench cracking and must be tempered immediately usually within 15 minutes of quenching to avoid problems. C, followed by slow cooling no quench reducing the problem of distortion. If the work is not tempered right away, quench cracks can and will occur. Quench cracking in steel as a case of hydrogen embrittlement. Fourquenchingbathsofabout18 galloncapacityeachnamely,water,60percentglycerininwater.
Quench cracking of steel cracking resulting from stresses produced during the austenite to martensite transformation during heat treating quenching and tempering. Asquenched martensite is hard and brittle it has virtually no ductility. Cooling in ash or lime after forging is recommended. Quench cracks 3 ways to recognize speaking of precision.
Jade band marigold introduction atlas 4340 is a nominally 1. External corners need to at least be broken before heat treat, as they too are a stress concentration area. Nitriding should be followed by slow cooling no quench reducing the problem of distortion. Oil and gas completion equipment such as packers and liner hanger components and wellhead components. It is an alloy structural grade which used by the sae. And it has good toughness, fatigue resistance, impact toughness and etc. If the use of water as quenching medium, 4140 steel cooling speed is faster at high temperature range, but the cooling speed is slow at low temperature range lower than the ms temperature. Conditions producing cracks in a particular oilhardening steel were determined. Heat treating and brine quench of prepost machined 4340.