B7 studs are, according to several "stud" sites, 4140 with a hardness of RC28-32. When it is RC28-32 most sites call it prehard or some other name, is that the same as 4140 half hard or is that something different again
b7 stud material
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b7 stud material
The shortest distance between two points is a circle of infinite diameter.
Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/
Southwestern Ontario. CanadaTags: None
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Originally posted by loose nut View PostB7 studs are, according to several "stud" sites, 4140 with a hardness of RC28-32. When it is RC28-32 most sites call it prehard or some other name, is that the same as 4140 half hard or is that something different againLocation: Helsinki, Finland, Europe
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Originally posted by loose nut View PostB7 studs are, according to several "stud" sites, 4140 with a hardness of RC28-32. When it is RC28-32 most sites call it prehard or some other name, is that the same as 4140 half hard or is that something different again
I think that prehard and half hard is the same although I find it confusing. 4140 HT refers to a hardness of RC28-32.Last edited by enginuity; 08-14-2017, 09:33 AM.
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Hmm.. I know ALOT about B7...but your question is about 4140HT.. .of which I know some.
ASTM A193 B7 is a bolting spec, primarly for flanges. Bolts are made from 414X and then through heat treated and then test against the spec. No half hard or anything like that.
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If you buy 4140 Annealed, it is called 4140 Ann
Normally 4140 is sold as 4140 HT ---while HT means heat treated, it really is not heat treated to max hardness and is in the 28-32 RC range.
That means it is partially heat treated and some call it Prehard, or half hard. HT means the same
All our die material was forged and heat treated to RC 28-32.
When macjined we had it heat treated to 40-44
RichGreen Bay, WI
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I'm guessing here because I don't have the spec handy. Doesn't B7 specify a minimum tensile strength at elevated temperatures? 4140 was developed as a universal through hardening alloy steel suitable for high strength applications at elevated temperatures. Among the target requirements included weldability, resistance to fatigue, metallurgical complications, and be low in alloy constituents to minimize impact on strategic materials.
Back is the day, I worked many 1200 PSI steam system components: valves, turbines etc and the studs were required to perform at super-heated steam at 1050 degrees F. We used a mod of B16 1222. Anyway 4140 and modifications fulfill the requirements of the relevant standards for high strength high temperature fasteners.
Hold the phone! I think I found the standard (ASTM A193M) or at least a dolled up short version:
If you want to look at the full spec you'll have to track it down in a technical or engineering library or pony up $51 and buy it from the blood suckers. It covers a lot more than B7 fastener material.Last edited by Forrest Addy; 08-15-2017, 03:50 AM.
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Originally posted by Forrest Addy View PostI'm guessing here because I don't have the spec handy. Doesn't B7 specify a minimum tensile strength at elevated temperatures?I just need one more tool,just one!
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Just to complicate things here is another ?
Studs, large ones at least, are frequently torqued down on vessels, furnaces etc. Would an old stud that has been under torque strain for an unknown length of time under go any change in it's physical properties. This is in regards to using an old stud as 4140 material for non critical jobs. IE: at homeThe shortest distance between two points is a circle of infinite diameter.
Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/
Southwestern Ontario. Canada
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Originally posted by loose nut View PostJust to complicate things here is another ?
Studs, large ones at least, are frequently torqued down on vessels, furnaces etc. Would an old stud that has been under torque strain for an unknown length of time under go any change in it's physical properties. This is in regards to using an old stud as 4140 material for non critical jobs. IE: at home
Our technology is literally bolted together. Should relaxation of fastener tension have ever been a problem you can bet there'd be tons of technical material describing it, measures to take to prevent it, and lengthy units in engineering and trade schools discussing the phenomena.
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Originally posted by Forrest Addy View PostNo. Not in my geologically long experience in steam and diesel which involved zillions of heavy duty bolted connections. Never have I disassembled fasters long in service where they've taken a "set" or relaxed in tension - provided they never exceeded yield.
Our technology is literally bolted together. Should relaxation of fastener tension have ever been a problem you can bet there'd be tons of technical material describing it, measures to take to prevent it, and lengthy units in engineering and trade schools discussing the phenomena.
I believe the only exception to this would be a torque to yield fastener.Home, down in the valley behind the Red Angus
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Location: British Columbia
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Originally posted by Forrest Addy View PostNo. Not in my geologically long experience in steam and diesel which involved zillions of heavy duty bolted connections. Never have I disassembled fasters long in service where they've taken a "set" or relaxed in tension - provided they never exceeded yield.Location: Helsinki, Finland, Europe
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Originally posted by Forrest Addy View PostNo. Not in my geologically long experience in steam and diesel which involved zillions of heavy duty bolted connections. Never have I disassembled fasters long in service where they've taken a "set" or relaxed in tension - provided they never exceeded yield.
Our technology is literally bolted together. Should relaxation of fastener tension have ever been a problem you can bet there'd be tons of technical material describing it, measures to take to prevent it, and lengthy units in engineering and trade schools discussing the phenomena.
Most of the relaxation happens within the first 20-30 minutes though and clamp load usually stabilizes within a few days if the joint does not see a lot of thermal variation, so you are partly correct in that fastener relaxation is not a long term thing in most cases.Last edited by Yondering; 08-15-2017, 02:25 PM.
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Thanks for the info.The shortest distance between two points is a circle of infinite diameter.
Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/
Southwestern Ontario. Canada
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