Does steel have "grain" or does the forming process affect the properties of a piece?
This may be an odd question. Does steel have "grain" or a stronger/weaker plane or axis like wood does?
Obviously steel comes formed in many different shapes such as channel, angle, flat bar, round bar, sheet, etc. What I am wondering is if there are ways that any particular shape of steel shouldn't be used. For example, I need to make some pin bosses for an excavator attachment that I'm making. Ideally, I would make them out of a piece of round bar, cut to length and drilled for the pin hole. But at the moment I only have flat bar available, so I was thinking I would cut a piece of the proper thickness flat bar, and cut it as close as I can to round with a grinder, and then finish it in the lathe. But I'm wondering if the strength properties would be any different doing it this way as opposed to using a piece of steel that is formed round to start with.
In this case I'm sure it doesn't matter because it will be welded all the way around. But, the question came up in my mind so I figured I'd ask.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Hi Glen,
very thoughtful question you have there! Yes, steel does have grain, and you can see it in cold rolled sheet metal, if you look close. But it is not the same as wood when it comes to strength properties. About the only time it ever mattered in my career was when working in precision sheet metal shop. And in that situation, what mattered was that all the material was sheared in the same direction, so all of the forming(bending) was either with or against the grain on every bend. Meaning, that if some of the parts were sheared with the grain, and some were sheared perpendicular to the grain, though all the same size, punched and notched the same, when the forming operations were done, the dimensions of the bends could differ, due to the grain of the metal. But, this is an extreme example, as the tolerances were sometimes plus or minus .005 on the bends. Strengthwise, it didn't matter, the only concern was for the dimensions on bends for real close tolerance work. This was in a shop where half the work was done on manually set up and punched machines, and half was CNC turret punched(where all of the parts, theoretically, are punched the same direction, assuming the original blanks fed to the machine were sheared the same-it's a good bet they always were!) With the project you are doing, it is nothing to worry about. Good luck, and take care,
Re: Does steel have "grain" or does the forming process affect the properties of a pi
i think it does. i dont know how critical it is. i suppose if ur making a sharp bend in it, it would be something to think about more. ive seen cert test plates used both way, and coupon bent, havent seen a problem. big steel distributor that sells pieces of plate (not mild) paints the direction of the grain on them if sold partial/rem/drop. i tried reading a couple times what ur describing, but i cant comprehend it
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Re: Does steel have "grain" or does the forming process affect the properties of a pi
Originally Posted by Diacro Don
Hi Glen,
very thoughtful question you have there! Yes, steel does have grain, and you can see it in cold rolled sheet metal, if you look close. But it is not the same as wood when it comes to strength properties. About the only time it ever mattered in my career was when working in precision sheet metal shop. And in that situation, what mattered was that all the material was sheared in the same direction, so all of the forming(bending) was either with or against the grain on every bend. Meaning, that if some of the parts were sheared with the grain, and some were sheared perpendicular to the grain, though all the same size, punched and notched the same, when the forming operations were done, the dimensions of the bends could differ, due to the grain of the metal. But, this is an extreme example, as the tolerances were sometimes plus or minus .005 on the bends. Strengthwise, it didn't matter, the only concern was for the dimensions on bends for real close tolerance work. This was in a shop where half the work was done on manually set up and punched machines, and half was CNC turret punched(where all of the parts, theoretically, are punched the same direction, assuming the original blanks fed to the machine were sheared the same-it's a good bet they always were!) With the project you are doing, it is nothing to worry about. Good luck, and take care,
Don
Don, thanks for the quick and informative response! Much appreciated.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Originally Posted by 123weld
i think it does. i dont know how critical it is. i suppose if ur making a sharp bend in it, it would be something to think about more. ive seen cert test plates used both way, and coupon bent, havent seen a problem. big steel distributor that sells pieces of plate (not mild) paints the direction of the grain on them if sold partial/rem/drop. i tried reading a couple times what ur describing, but i cant comprehend it
Thanks 123,
I'm not good with descriptions sometimes... I'll post a picture when I start working on them.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Originally Posted by ArcTan
Thanks 123,
I'm not good with descriptions sometimes... I'll post a picture when I start working on them.
and im not good at understanding, especially in the evening
The individual is handicapped by coming face to face w/ a conspiracy so monstrous, he cannot believe it exists. The American mind, simply has not come to a realization of the evil which has been introduced in our midst. - fbi dir j e hoover
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Hi 123Weld,
good point! I forgot about that point! When taking or doing D1.1 weld tests, the coupons should be cut out of 7" wide plate, 3" long, rather than 3" wide material 7" long, for the reason that when doing the bend test, they are less likely to break due to the grain of the material! But again, an extreme example....
Take care,
Don
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Lamellar tearing, a weld defect, looks like a problem related to grain but it is more to do with poor rolling.
The crystalline structure of steel has a "grain" but the grains are not aligned so it does not have a "grain" like wood. But once it is rolled, the crystalline grain can align - that, with the help of some inclusions in the rolling process, can lead to lamellar tearing.
Rolled steel has different (lower) ductility perpendicular to the plane of the rolling so, in addition lamellar tearing, the orientation of the steel in use matters.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Used to run into that problem when I was running the brake and shear where I used to work many moons ago. Depending on where the plate came from, when bending parallel with the grain you could see cracks and splits in the outside corner of the bend and on a rare occasion it would even show up all along the outside of the bend. For some odd reason, 3/8" seemed to be the worst even when using larger dies than needed.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Originally Posted by ArcTan
This may be an odd question. Does steel have "grain" or a stronger/weaker plane or axis like wood does?
Obviously steel comes formed in many different shapes such as channel, angle, flat bar, round bar, sheet, etc. What I am wondering is if there are ways that any particular shape of steel shouldn't be used. For example, I need to make some pin bosses for an excavator attachment that I'm making. Ideally, I would make them out of a piece of round bar, cut to length and drilled for the pin hole. But at the moment I only have flat bar available, so I was thinking I would cut a piece of the proper thickness flat bar, and cut it as close as I can to round with a grinder, and then finish it in the lathe. But I'm wondering if the strength properties would be any different doing it this way as opposed to using a piece of steel that is formed round to start with.
In this case I'm sure it doesn't matter because it will be welded all the way around. But, the question came up in my mind so I figured I'd ask.
The size/orientation of the grain structure probably won't matter based on the description of your application but it's always a good thing to think about. Grain structure is far more important for forming processes like a press brake.
There is often a difference in steel strength based on how the steel is made, which is determined by grain structure. Cold rolled flat bar will have a different grain structure than forged round bar which will differ from hot rolled steel.
Because hot rolling happens above the temperature at which steel forms new crystals (called the recrystallization temperature), you can see that the grain structure after hot rolling is very similar to what it was before rolling because the grains have recrystallized. The cold rolled steel on the other hand has a different grain structure because the grains were deformed below the recrystallization temperature so they permanently change shape. That's why cold rolled steel is usually stronger than the same type that's only hot rolled.
If your flat bar is hot rolled, and you buy a hot rolled piece of round bar, their mechanical properties are going to be very similar. If one is hot rolled and other is cold rolled then they will have different mechanical properties.
Welding creates temperatures above the recrystallization temp of the base metal in the heat affected zone. Which generally means you get some grain growth and the HAZ becomes weaker than it was. If you use cold rolled steel to make something and you weld on it, make sure that the weakened HAZ is still strong enough for whatever the application is.
From The AWS Welding Handbook:
The heat of welding will recrystallize the heat-affected zones in cold worked metals and soften the metal considerably. The weld cross section shown in figure 4.26 illustrated the effect of weld thermal cycles on cold worked microstructures, the weld metal is indicated by area (C). The unaffected base metal (A) shows the typical elongated grains resulting from mechanical deformation (cold rolling). Fine grains were formed where the heat-affected zone temperature exceeded the recrystallization temperature (B) and grain growth took place at higher temperatures near the fusion zone (area between C and B). The heat-affected zone adjacent to the weld is softer and weaker than the cold worked base metal and the strength cannot be recovered by heat treatment.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Originally Posted by Thoriated Wolfram
The size/orientation of the grain structure probably won't matter based on the description of your application but it's always a good thing to think about. Grain structure is far more important for forming processes like a press brake.
There is often a difference in steel strength based on how the steel is made, which is determined by grain structure. Cold rolled flat bar will have a different grain structure than forged round bar which will differ from hot rolled steel.
Because hot rolling happens above the temperature at which steel forms new crystals (called the recrystallization temperature), you can see that the grain structure after hot rolling is very similar to what it was before rolling because the grains have recrystallized. The cold rolled steel on the other hand has a different grain structure because the grains were deformed below the recrystallization temperature so they permanently change shape. That's why cold rolled steel is usually stronger than the same type that's only hot rolled.
If your flat bar is hot rolled, and you buy a hot rolled piece of round bar, their mechanical properties are going to be very similar. If one is hot rolled and other is cold rolled then they will have different mechanical properties.
Welding creates temperatures above the recrystallization temp of the base metal in the heat affected zone. Which generally means you get some grain growth and the HAZ becomes weaker than it was. If you use cold rolled steel to make something and you weld on it, make sure that the weakened HAZ is still strong enough for whatever the application is.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Originally Posted by ArcTan
This may be an odd question. Does steel have "grain" or a stronger/weaker plane or axis like wood does?
Obviously steel comes formed in many different shapes such as channel, angle, flat bar, round bar, sheet, etc. What I am wondering is if there are ways that any particular shape of steel shouldn't be used. For example, I need to make some pin bosses for an excavator attachment that I'm making. Ideally, I would make them out of a piece of round bar, cut to length and drilled for the pin hole. But at the moment I only have flat bar available, so I was thinking I would cut a piece of the proper thickness flat bar, and cut it as close as I can to round with a grinder, and then finish it in the lathe. But I'm wondering if the strength properties would be any different doing it this way as opposed to using a piece of steel that is formed round to start with.
In this case I'm sure it doesn't matter because it will be welded all the way around. But, the question came up in my mind so I figured I'd ask.
Short answer for grain is yes.
You'll see this in recommendations for orientation when bending sheet.
Dave J.
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Re: Does steel have "grain" or does the forming process affect the properties of a pi
Yes
It comes from rolling.
It only a problem when forming.
Welding typically never a problem or I never had problem
Dave
FYI I did forming too and at times it was a problem
Originally Posted by ArcTan
This may be an odd question. Does steel have "grain" or a stronger/weaker plane or axis like wood does?
Obviously steel comes formed in many different shapes such as channel, angle, flat bar, round bar, sheet, etc. What I am wondering is if there are ways that any particular shape of steel shouldn't be used. For example, I need to make some pin bosses for an excavator attachment that I'm making. Ideally, I would make them out of a piece of round bar, cut to length and drilled for the pin hole. But at the moment I only have flat bar available, so I was thinking I would cut a piece of the proper thickness flat bar, and cut it as close as I can to round with a grinder, and then finish it in the lathe. But I'm wondering if the strength properties would be any different doing it this way as opposed to using a piece of steel that is formed round to start with.
In this case I'm sure it doesn't matter because it will be welded all the way around. But, the question came up in my mind so I figured I'd ask.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Wolfram....thanks very much for showing the difference in hot and cold rolling...being a smith, I was always curious as to why the cold seemed to move slightly differently and was always cleaner to start with...no scale.
Re: Does steel have "grain" or does the forming process affect the properti
Yes steel does have grain. Not quite the same but when some steels are shot peened they develop a hardness on the outside similar to a case hardness. Connecting rods are shot peened sometimes cause its beneficial for them. My experience is with differental pinions and axle shafts. They were shot peened to get a "compacted" harder surface then hardened and tempered for the correct properties.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
Originally Posted by ArcTan
This may be an odd question. Does steel have "grain" or a stronger/weaker plane or axis like wood does?
Obviously steel comes formed in many different shapes such as channel, angle, flat bar, round bar, sheet, etc. What I am wondering is if there are ways that any particular shape of steel shouldn't be used. For example, I need to make some pin bosses for an excavator attachment that I'm making. Ideally, I would make them out of a piece of round bar, cut to length and drilled for the pin hole. But at the moment I only have flat bar available, so I was thinking I would cut a piece of the proper thickness flat bar, and cut it as close as I can to round with a grinder, and then finish it in the lathe. But I'm wondering if the strength properties would be any different doing it this way as opposed to using a piece of steel that is formed round to start with.
In this case I'm sure it doesn't matter because it will be welded all the way around. But, the question came up in my mind so I figured I'd ask.
Steel does have a grain structure, just like other materials such as wood or ceramics. The grain structure of steel refers to the arrangement of its crystal grains, which can affect its mechanical properties. The direction of the grain structure can have an impact on the strength and ductility of the steel.
The forming process can also affect the properties of a piece of steel. For example, rolling, forging, or extruding can change the grain structure of the steel and alter its mechanical properties. In general, when steel is formed by rolling or extruding, the grain structure becomes elongated in the direction of the rolling or extruding force. This can result in improved strength and toughness in that direction, but reduced properties in other directions.
In your specific case, using a flat bar and shaping it to a round shape should not significantly affect the strength properties of the steel, especially since it will be welded all the way around. However, if you were using the flat bar in a different application where the direction of the grain structure would be more critical, it might be better to use a different form of steel that is better suited for that application.
Re: Does steel have "grain" or does the forming process affect the properties of a pi
The diagram with hot rolled and cold rolled is excellent! This same concept applies to casting versus forging versus billet. Casting will have random grains, forging will have directional grain. Things machined from billet should generally have directional grain, which it got from the previous cold rolling, and hopefully whoever machined it didn’t cut it across the grain. But steel isn’t quite like wood. Wood is probably 100x stronger with the grain vs against the grain, where steel is maybe 10% stronger with the grain (that’s a complete guess, but it makes the point).
Generally speaking the grains are strong and failures happen on the grain boundary, just like wood splits between grains. So something like a engine connecting rod should be built like you were making it out of wood, with the grain going the long way. Weldments frequently fail in the heat effected zone because the HAZ is recast metal with random grain. What about a bolt? It should be manufactured so the grain goes lengthwise to resist pulling.
What about a pin in a shackle (in SHEAR)? That should also go the long wise, think about a dowel versus cutting discs of plywood and laminating them. So to answer the OP’s question, what about a pin BOSS? That’s more like a washer, right? It doesn’t really matter which way the grain goes.
hope that makes sense.
Joe
Last edited by SmokinJoe; 10-27-2023 at 01:40 PM.
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