When you oil quench steel forgings, theres also less risk of cracking compared to water quenching or polymer quenching. Quench from 16001650f water 50 fpm, 1 gallon water per lb of castings remove highce parts at 300400f and air cool. Temper etching dilute nitric acid in water revealed the presence of abusive grinding. Contact your local metal supermarkets store to confirm availability and pricing. In the past, ductility and weldability came at a cost to strength and toughness. This chapter presents guidelines for minimizing quench cracking in medium carbon and alloy steels, e. Will this specimen experience fracture if the largest surface crack is 0. Quench cracking in steel as a case of hydrogen embrittlement. Alloy depletion quench cracking heat treatment defects alloy depletion quench cracking heat treatment defects alloy depletion in aisi 4140 steel heat treatment defects alloy inclusion defects quench cracking heat treatment defects alloy inclusion defects quench cracking. Typically, this is related to wrong procedures or improperly speci. Welding of steel 4340 in the hardened and tempered condition as normally supplied, is not recommended and should be avoided if at all possible, because of the danger of quench cracking, as the mechanical properties will be altered within the weld heat affected zone. These advantages are realized principally where high strength is required in heavy sections. The crack is seen to travel along the prior austenite grain boundaries.
The planestrain fracture toughness of quenched and tempered aisi 4340. Alloy 4340 plate is another general purpose grade of steel used for industrial and machining applications. Throughhardening low alloy steel bar 4340 colour code. Material and process selection can contribute to cracking as well. I would like to keep my eyes open for a deal on possible plates so if i ever do try to plate quench i would have the plates on hand. Atlas 4340 can be surface hardened to 58hrc water quench or surface hardened to between 53 to 55hrc oil quench. With our state of the art plate mill, we produce plates up to 2500 mm in width. It can be avoided by first plating the steel with nickel.
It is ideal for achieving the required strength and hardness properties on many alloys. The graph bars on the material properties cards below compare quenched and tempered saeaisi 4140 to. The key to reducing warpage is to grind as symmetrically as possible on each side. Coarsely grained steels increase hardening depth and are more prone to quench cracking than fine grain steels. The martensitic transformation starts at the outermost surfaces of the part being quenched. Sij acroni is the largest slovenian steel manufacturer and one of the leading quarto plate producers in europe, producing steel by recycling scrap in an electric arc furnace, casting it on a continuous caster and rolling it into high quality flat rolled steel products. Ar400 is a quench and tempered steel and may be difficult to weld due its high strength and hardenability. Overview of the mechanisms of failure in heat treated steel components 45. Richly alloyed heavyduty steel, this nickelchromium molybdenum alloy possesses much deeper hardenability than the 4100 series, with increased ductility and toughness.
However, as in motor shaft applications, under quenching and tempering conditions, 4340 steel typically use high preheating in low hydrogen processes. Itemdimension is thickness in inches find your closest store 0. And it has good toughness, fatigue resistance, impact toughness and etc. They run between the grains of the steel and to the unaided eye look somewhat like a river on a map. Parts can therefore be machined to near final size, leaving a grinding allowance only. Aluminum draws the heat out of the steel very fast including the portions not in direct contact with the plates and if done properly keeps the blade very straight.
Quench cracking may appear to propagate along a banded area, but it is rare that the crack occurred because of this microstructure variation. Nov 16, 2015 i use aluminum quench plates when working with thin o64 and 2. Maraging was from a 11 mm plate cut from a forged cylinder. I have had issues with cracks in 4340, that initiate from holes such as this. The inclusion of nickel in alloy 4340 helps simplify heat treatment. Us4404047a process for the improved heat treatment of. Root cause in my case, after removing as much of the quench aggressiveness as possible, was the surface finish of the hole. Now, theres quenched and tempered steel, a high strength and abrasionresistant steel that comes with enhanced fabrication qualities. I dont think a plate would work on the steels i use.
Jade band marigold introduction atlas 4340 is a nominally 1. Nitriding is carried out at 490 o c 530 o c, followed by slow cooling no quench reducing the problem of distortion. Here are seven ways that steel can fail as a result of quench cracking from heat treatment. Alloy steel 4340 steel plate metal supermarkets steel. Keep alloy c quench for preexisting flaws, repair before quench 3. Commercial and military aircraft, automotive systems, forged hydraulic and other machine tool applications, forged steel crankshafts. Welding is not recommended because of the danger of quench cracking. The quench cracking that occurs in steels with carbon contents greater than about 0.
While large 4140 rounds can be waterquenched, squares are a different story. Due to availability the astm 4340 grade steel is often substituted with european based standards 817m40en24 and 1. Throughhardening low alloy steel bar 4340 atlas steels. The hot parts are then quenched in a liquid, usually oil for medium carbon plate or alloy plate like 1045, 4140, or 4340 or water for low carbon alloy grades like a514. Quench cracks 3 ways to recognize speaking of precision blog. 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. It is commonly used for plate applications that are between three and six inches thick. 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. I taper the tang on everything and have only my flats in contact with plates, and hardly ever have warpage mainly because i try to make the blade as symmetric as possible. Aisi 4340 steel, oil quenched 855c 1570f, 230c 450f. If the steel is an oilhardening steel, the use of these overly aggressive quenchants will lead to cracking. There are 484 suppliers who sells 4340 steel plate on, mainly located in asia. This is a process that strengthens and hardens ironbased alloys by heating, rapidly cooling, and.
What are you recommendations for welding ar400 plate. 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. Although it is chromium steel and often referred to as chromoly steel, it does not contain as much chromium as stainless steel. This is due to the very high hardenability which causes a severe volume change gradient going from austenite to martensite through the thickness.
Welding welding is not recommended because of the danger of quench cracking. The base steel around the weld rapidly heats and cools during welding, resulting in a heat affected zone haz with high hardness. Heat treating can definately cause 4340 to crack, especially a poorly designed part, or a part that is incorrectly heat treated. Quench cracks 3 ways to recognize speaking of precision. The 800 600 400 200 30 oil 60 90 time, s 120 150 o fig. Avoid overheating and overly long dwell times while austenitizing. Sae aisi 4340 steel properties, heat treatment, equivalent. A process for the energy efficient heat treatment of steels wherein a steel workpiece is rapidly heated to a temperature above the a 3 temperature of the steel to convert the steel to austenite, the workpiece is then rapidly quenched in a liquid quench medium to convert the austenite to a predominantly martensitic microstructure, and the steel is then tempered by rapid heating while the. This article discusses overheat ing and burning, residual stresses, quench cracking, and distortion in some detail and offers some suggestions to combat them. Standard mill sizes for alloy steel 4340 steel plate range from. Oct 14, 2009 im no expert but ive been plate quenching for almost a year now, its an excellent way to quench air hardening steels. Carefull design is as important as choosing a heat treater who can correctly heat treat 4340, not all of them can.
The first step in the quenchandtemper is to heat the parts to a uniform temperature above the transformation range, usually about 1650. 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. 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. Microstructure and mechanical properties of laser cladding.
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. As a result of this intermediate cooling rate, the parts will possess a hardness and strength somewhat greater than if annealed but somewhat less than if quenched and tempered. Oil quenching is a common method for hardening alloy steel forgings. One of the common treatments to achieve this is quenching and tempering. The structures obtained by these heattreat ments are hereafter referred to as the 870 and the 1200870 structures respectively.
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. Quenched and tempered saeaisi 4140 is saeaisi 4140 steel in the quenched and tempered condition. How to quenching and tempering of 4140 alloy steel. Influence of austenitizing on the mechanical properties of. 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. In addition, the nickel in alloy 4340 increases hardenability of the steel. Jun 04, 2012 i am going to post this i think i know what the issue was but would like some other input. It has the highest strength compared to the other variants of saeaisi 4140 steel. Before we launch into a list of benefits and applications, lets first outline how quenched and tempered steel plate is produced.
If there is decarb associated with a crack, that shows that the crack existed at the time the material was at temperatures hot enough to decarburize. It is a nickelchromiummolybdenum medium carbon alloy steel with deep hardenability. Overheating during the austenitizing portion of the heat treatment cycle can coarsen normally fine grained steels. According to the actual production situation, we believe that the main reason of quenching crack of 4140 steel plate is.
Yes, water, brine or caustic will get the steel harder. Overviewofthemechanismsoffailure in heat treated steel. Since the crack usually appears during the quench, it is common to find a light gray scale within the quench crack that develops during the temper cycle. While the tempering of steel has been developed over thousands of years, aluminum is a much newer metal and the quenching techniques are more recent. Following forging operation the work piece should be cooled as slowly as. This may be why people are more likely to associate quenching with stainless steel, even though it is certainly possible to quench aluminum if. Steel is strong to begin with, but sometimes its necessary to make it even stronger. The hot parts are then quenched in a liquid, usually oil for medium carbon plate or alloy plate like 1045, 4140, or 4340 or. Sitemap contact 26800 miles road, bedford heights, oh 44146 800 5485493 ph. Here are 7 ways that steel can fail as a result of quench cracking from heat treatment. C, followed by slow cooling no quench reducing the problem of distortion.
For the record if i ever do try to plate quench, i would be waiting till i had a kiln so i had. Conditions producing cracks in a particular oilhardening steel were determined experimentally. Aisi 4340 steel stockholders and suppliers, delivering to the whole of the uk. The best way to prevent cracking would be to anneal the 4140 part before welding.
Also the high fatigue strength of 4340 makes it ideal for all highly stressed parts. It is possible to weld 4140 quenched and tempered but you have to be ok with at least some cracking. Aisi 4340 steel plates of dimension 180 mm x 100 mm x 6 mm composition shown in table. 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. In normalizing, the cooling rate is slower than that of a quench andtemper operation but faster than that used in annealing. Therefore the corrosion resistant is improved compared. Aisisae 4340 alloy steel 4340 steel properties all metals. Atlas 4340 is an alternative to atlas 6582 throughhardening steel and to. The hot parts are then quenched in a liquid, usually oil for medium carbon plate or alloy plate like 1045, 4140, or 4340 or water for low carbon alloy grades like. It is an alloy structural grade which used by the sae. Zuk et al properties and structure of the weld joints of quench and tempered 4330v steel metalurgija 55 2016 4, 6616 although the material has a high hardenability, the hardness is expected to be lower further away from the surface and higher closer to the surface, so there will be.