Bruno2 Posted March 12, 2018 Author Share Posted March 12, 2018 Brandon called to ask what I know about stainless fasteners, which isn't much. My Carroll Smith Nuts, Bolts, Fasteners and Plumbing Handbook doesn't appear to say much about them. But my Pocket Reference by Thomas J. Glover says that both 18-8 and 316 stainless have 75,000 lb/sq inch minimum tensile strength. On-line I found that the Bolt Depot says this: Stainless Steel Stainless steel is an alloy of low carbon steel and chromium for enhanced corrosion characteristics. Stainless steel is highly corrosion resistant for the price. Because the anti-corrosive properties are inherent to the metal, it will not lose this resistance if scratched during installation or use. It is a common misconception that stainless steel is stronger than regular steel. In fact, due to their low carbon content, many stainless steel alloys cannot be hardened through heat treatment. Therefore, when compared to regular steel, the stainless alloys used in bolts are slightly stronger than an un-hardened (grade 2) steel but significantly weaker than hardened steel fasteners. Unless great care is taken, stainless fasteners are susceptible to seizing up during installation, a phenomenon known as galling. Most stainless steel fasteners are much less magnetic than regular steel fasteners though some grades will be slightly magnetic. 18-8 Stainless 18-8 refers to any stainless steel containing approximately 18% chromium and 8% nickel. This is the most common stainless designation for hardware. For information on 18-8 stainless steel material properties see our Material Grade Identification and Properties Chart. Stainless 316 A highly corrosion resistant grade of stainless steel. Ideal in salt water and chlorine environments. More expensive than 18-8. Stainless 410 A stainless alloy that is harder than 18-8 stainless steel, but not as resistant to corrosion. And Fastenal says this is their Technical Reference Guide on fasteners: Stainless Steel Stainless steel is a family of iron-based alloys that must contain at least 10.5% chromium. The presence of chromium creates an invisible surface film that resists oxidation and makes the material “passive” or corrosion resistant. Other elements, such as nickel or molybdenum are added to increase corrosion resistance, strength or heat resistance. Stainless steels can be simply and logically divided into three classes on the basis of their microstructure; austenitic, martensitic or ferritic. Each of these classes has specific properties and basic grade or “type.” Also, further alloy modifications can be made to alter the chemical composition to meet the needs of different corrosion conditions, temperature ranges, strength requirements, or to improve weldability, machinability, work hardening and formability. Austenitic stainless steels contain higher amounts of chromium and nickel than the other types. They are not hardenable by heat treatment and offer a high degree of corrosion resistance. Primarily, they are nonmagnetic; however, some parts may become slightly magnetic after cold working. The tensile strength of austenitic stainless steel varies from 75,000 to 105,000 psi. 18-8 Stainless steel is a type of austenitic stainless steel that contains approximately 18% chromium and 8% nickel. Grades of stainless steel in the 18-8 series include, but not limited to; 302, 303, 304 and XM7. Common austenitic stainless steel grades: • 302: General purpose stainless retains untarnished surface finish under most atmospheric conditions and offers high strength at reasonably elevated temperatures. Commonly used for wire products such as springs, screens, cables; common material for flat washers. • 302HQ: Extra copper reduces work hardening during cold forming. Commonly used for machine screws, metal screws and small nuts • 303: Contains small amounts of sulfur for improved machinability and is often used for custom-made nuts and bolts. • 304: Is a low carbon-higher chromium stainless steel with improved corrosion resistance when compared to 302. 304 is the most popular stainless for hex head cap screws. It is used for cold heading and often for hot heading of large diameter or long bolts. • 304L: Is a lower carbon content version of 304, and therefore contains slightly lower strength characteristics. The low carbon content also increases the 304L corrosion resistance and welding capacity. • 309 & 310: Are higher in both nickel and chromium content than the lower alloys, and are recommended for use in high temperature applications. The 310 contains extra corrosion resistance to salt and other aggressive environments. • 316 & 317: Have significantly improved corrosion resistance especially when exposed to seawater and many types of chemicals. They contain molybdenum, which gives the steel better resistance to surface pitting. These steels have higher tensile and creep strengths at elevated temperatures than other austenitic alloys. Austenitic stainless steel limitations: • They are suitable only for low concentrations of reducing acids. • In crevices and shielded areas, there might not be enough oxygen to maintain the passive oxide film and crevice corrosion might occur. • Very high levels of halide ions, especially the chloride ion can also break down the passive surface film. Martensitic stainless steels are capable of being heat treated in such a way that the martensite is the prime microconstituent. This class of stainless contains 12 to 18% chromium. They can be hardened by heat treatment, have poor welding characteristics and are considered magnetic. The tensile strength of 5 martensitic stainless steel is approximately 70,000 to 145,000 psi. This type of stainless steel should only be used in mild corrosive environments. Common martensitic stainless steel grades: • 410: A straight chromium alloy containing no nickel. General-purpose corrosion and heat resisting, hardenable chromium steel. It can be easily headed and has fair machining properties. Due to their increased hardness, are commonly used for self-drilling and tapping screws. These are considered very inferior in corrosion resistance when compared with some of the 300. • 416: Similar to 410 but has slightly more chromium, which helps machinability, but lowers corrosion resistance. Ferritic stainless steels contain 12 to 18% chromium but have less than 0.2% carbon. This type of steel is magnetic, non-hardenable by heat treatment and has very poor weld characteristics. They should not be used in situations of high corrosion resistance requirements. Common ferritic stainless steel grades: • 430: Has a slightly higher corrosion resistance than Type 410 stainless steel. Precipitation Hardening Stainless Steel Precipitation hardening stainless steels are hardenable by a combination of low-temperature aging treatment and cold working. Type 630, also known commercially as 17-4 PH, is one of the most widely used precipitated hardened steels for fasteners. They have relatively high tensile strengths and good ductility. The relative service performance in both low and high temperatures is reasonably good. looks like 430 is the way to go. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 13, 2018 Share Posted March 13, 2018 Brandon called to ask what I know about stainless fasteners, which isn't much. My Carroll Smith Nuts, Bolts, Fasteners and Plumbing Handbook doesn't appear to say much about them. But my Pocket Reference by Thomas J. Glover says that both 18-8 and 316 stainless have 75,000 lb/sq inch minimum tensile strength. On-line I found that the Bolt Depot says this: Stainless Steel Stainless steel is an alloy of low carbon steel and chromium for enhanced corrosion characteristics. Stainless steel is highly corrosion resistant for the price. Because the anti-corrosive properties are inherent to the metal, it will not lose this resistance if scratched during installation or use. It is a common misconception that stainless steel is stronger than regular steel. In fact, due to their low carbon content, many stainless steel alloys cannot be hardened through heat treatment. Therefore, when compared to regular steel, the stainless alloys used in bolts are slightly stronger than an un-hardened (grade 2) steel but significantly weaker than hardened steel fasteners. Unless great care is taken, stainless fasteners are susceptible to seizing up during installation, a phenomenon known as galling. Most stainless steel fasteners are much less magnetic than regular steel fasteners though some grades will be slightly magnetic. 18-8 Stainless 18-8 refers to any stainless steel containing approximately 18% chromium and 8% nickel. This is the most common stainless designation for hardware. For information on 18-8 stainless steel material properties see our Material Grade Identification and Properties Chart. Stainless 316 A highly corrosion resistant grade of stainless steel. Ideal in salt water and chlorine environments. More expensive than 18-8. Stainless 410 A stainless alloy that is harder than 18-8 stainless steel, but not as resistant to corrosion. And Fastenal says this is their Technical Reference Guide on fasteners: Stainless Steel Stainless steel is a family of iron-based alloys that must contain at least 10.5% chromium. The presence of chromium creates an invisible surface film that resists oxidation and makes the material “passive” or corrosion resistant. Other elements, such as nickel or molybdenum are added to increase corrosion resistance, strength or heat resistance. Stainless steels can be simply and logically divided into three classes on the basis of their microstructure; austenitic, martensitic or ferritic. Each of these classes has specific properties and basic grade or “type.” Also, further alloy modifications can be made to alter the chemical composition to meet the needs of different corrosion conditions, temperature ranges, strength requirements, or to improve weldability, machinability, work hardening and formability. Austenitic stainless steels contain higher amounts of chromium and nickel than the other types. They are not hardenable by heat treatment and offer a high degree of corrosion resistance. Primarily, they are nonmagnetic; however, some parts may become slightly magnetic after cold working. The tensile strength of austenitic stainless steel varies from 75,000 to 105,000 psi. 18-8 Stainless steel is a type of austenitic stainless steel that contains approximately 18% chromium and 8% nickel. Grades of stainless steel in the 18-8 series include, but not limited to; 302, 303, 304 and XM7. Common austenitic stainless steel grades: • 302: General purpose stainless retains untarnished surface finish under most atmospheric conditions and offers high strength at reasonably elevated temperatures. Commonly used for wire products such as springs, screens, cables; common material for flat washers. • 302HQ: Extra copper reduces work hardening during cold forming. Commonly used for machine screws, metal screws and small nuts • 303: Contains small amounts of sulfur for improved machinability and is often used for custom-made nuts and bolts. • 304: Is a low carbon-higher chromium stainless steel with improved corrosion resistance when compared to 302. 304 is the most popular stainless for hex head cap screws. It is used for cold heading and often for hot heading of large diameter or long bolts. • 304L: Is a lower carbon content version of 304, and therefore contains slightly lower strength characteristics. The low carbon content also increases the 304L corrosion resistance and welding capacity. • 309 & 310: Are higher in both nickel and chromium content than the lower alloys, and are recommended for use in high temperature applications. The 310 contains extra corrosion resistance to salt and other aggressive environments. • 316 & 317: Have significantly improved corrosion resistance especially when exposed to seawater and many types of chemicals. They contain molybdenum, which gives the steel better resistance to surface pitting. These steels have higher tensile and creep strengths at elevated temperatures than other austenitic alloys. Austenitic stainless steel limitations: • They are suitable only for low concentrations of reducing acids. • In crevices and shielded areas, there might not be enough oxygen to maintain the passive oxide film and crevice corrosion might occur. • Very high levels of halide ions, especially the chloride ion can also break down the passive surface film. Martensitic stainless steels are capable of being heat treated in such a way that the martensite is the prime microconstituent. This class of stainless contains 12 to 18% chromium. They can be hardened by heat treatment, have poor welding characteristics and are considered magnetic. The tensile strength of 5 martensitic stainless steel is approximately 70,000 to 145,000 psi. This type of stainless steel should only be used in mild corrosive environments. Common martensitic stainless steel grades: • 410: A straight chromium alloy containing no nickel. General-purpose corrosion and heat resisting, hardenable chromium steel. It can be easily headed and has fair machining properties. Due to their increased hardness, are commonly used for self-drilling and tapping screws. These are considered very inferior in corrosion resistance when compared with some of the 300. • 416: Similar to 410 but has slightly more chromium, which helps machinability, but lowers corrosion resistance. Ferritic stainless steels contain 12 to 18% chromium but have less than 0.2% carbon. This type of steel is magnetic, non-hardenable by heat treatment and has very poor weld characteristics. They should not be used in situations of high corrosion resistance requirements. Common ferritic stainless steel grades: • 430: Has a slightly higher corrosion resistance than Type 410 stainless steel. Precipitation Hardening Stainless Steel Precipitation hardening stainless steels are hardenable by a combination of low-temperature aging treatment and cold working. Type 630, also known commercially as 17-4 PH, is one of the most widely used precipitated hardened steels for fasteners. They have relatively high tensile strengths and good ductility. The relative service performance in both low and high temperatures is reasonably good. I really only find 304 and 316 nuts and bolts locally. And 409 for use as exhaust tubing. None of these external fasteners are critical or highly torqued. A water pump or exhaust manifold is likely to see 30-40 f-lb, oil pans and valve covers are in inches. No need to get crazy about choosing an alloy. Would I use cres for a flywheel or connecting rod? Not likely, but you could find jet nuts or superalloy aerospace fasteners that would exceed spec. Up here we used to have contractors that made and sold high quality fasteners to local businesses like Pratt & Whitney, and Sikorsky. Almost all of that manufacturing has gone, and with it the surplus/reject outlets. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 13, 2018 Share Posted March 13, 2018 I really only find 304 and 316 nuts and bolts locally. And 409 for use as exhaust tubing. None of these external fasteners are critical or highly torqued. A water pump or exhaust manifold is likely to see 30-40 f-lb, oil pans and valve covers are in inches. No need to get crazy about choosing an alloy. Would I use cres for a flywheel or connecting rod? Not likely, but you could find jet nuts or superalloy aerospace fasteners that would exceed spec. Up here we used to have contractors that made and sold high quality fasteners to local businesses like Pratt & Whitney, and Sikorsky. Almost all of that manufacturing has gone, and with it the surplus/reject outlets. Jim - What would you recommend for exhaust manifold bolts? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 13, 2018 Share Posted March 13, 2018 Jim - What would you recommend for exhaust manifold bolts? I'm not reccomending anything, just pointing out that almost *any* bolt will work for these applications. I used regular hardware store stainless bolts for the exhaust manifolds when i swapped my engine (10 years ago*!*) They are still shiny and have a full hex. Even the bolts in the waterpump jacket looked fine when I replaced it a year or two back. Carbon is higher on the galvanic (nobility?) scale than any metals. Often the higher rated fasteners are going to corrode faster due to the carbon in them. Electrolytics is not my forte but im assuming corrosion happens because dissimlar metals in the presence of an electrolyte and oxygen is scavenging metal ions. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 13, 2018 Share Posted March 13, 2018 I'm not reccomending anything, just pointing out that almost *any* bolt will work for these applications. I used regular hardware store stainless bolts for the exhaust manifolds when i swapped my engine (10 years ago*!*) They are still shiny and have a full hex. Even the bolts in the waterpump jacket looked fine when I replaced it a year or two back. Carbon is higher on the galvanic (nobility?) scale than any metals. Often the higher rated fasteners are going to corrode faster due to the carbon in them. Electrolytics is not my forte but im assuming corrosion happens because dissimlar metals in the presence of an electrolyte and oxygen is scavenging metal ions. I agree that about any bolt will work for these applications from a tension standpoint. Just wondering if you know what works from a corrosion standpoint. Sounds like about anything does. Thanks. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 13, 2018 Share Posted March 13, 2018 I agree that about any bolt will work for these applications from a tension standpoint. Just wondering if you know what works from a corrosion standpoint. Sounds like about anything does. Thanks. 430 is definitely corrosion resistant, but seems difficult to find in fasteners outside of chemical processing fields. Maybe better availability down there due to refineries and such. Does Bolt Depot offer 430 fasteners in the sizes needed? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 13, 2018 Share Posted March 13, 2018 430 is definitely corrosion resistant, but seems difficult to find in fasteners outside of chemical processing fields. Maybe better availability down there due to refineries and such. Does Bolt Depot offer 430 fasteners in the sizes needed? Haven't found 430's on the Bolt Depot, yet, but did find the following. Looks like lubrication is highly recommended with stainless. What is Thread Galling? Thread galling occurs during installation when pressure and friction cause bolt threads to seize to the threads of a nut or tapped hole. It is also known as "cold welding". Once a fastener has seized up from galling it is typically impossible to remove without cutting the bolt or splitting the nut. What Bolts Are Susceptible To Galling? Galling is most often seen in stainless steel (especially when using lock nuts), aluminum, and titanium. Fasteners with damaged threads and fine threads are particularly prone to galling. Hardened steel bolts, especially when zinc plated, rarely gall. What Can I Do to Prevent Galling? Slow Down Installation Speed Because heat generated by friction is a contributing factor in galling, slowing down the installation speed can prevent galling. It is recommended that power tools not be used for the installation of stainless steel or other fasteners prone to galling. This is especially important when using nylon insert lock nuts as these nuts significantly increase the chance of galling. Don't Use Bolts to Pull Joints Together Bolts are not designed to pull together a joint or force materials into position. Doing so drastically increases the chance of galling. The materials being bolted should already be in place so the nut can be spun down by hand until the final tightening. If necessary, use clamps to hold the joint together during bolting. Use a Lubricant Special anti-seizing or anti-galling lubricants can be used to dramatically reduce the chance of galling. Examples include MRO Solutions 1000 Antiseize, Permatex® Anti-Seize Lubricant, Finish Line™ Anti-Seize Assembly Lube and USS Ultra Tef-Gel®. Even a standard lubricant, such as WD-40®, can help reduce friction and prevent galling. Some nuts are available with a waxed finish to reduce the risk of galling. Avoid Damaged or Dirty Threads Check for damage to the threads of each bolt, especially bolts with fine thread. You should be able to put a standard nut on a bolt by hand. If not, it may indicate dented or damaged threads. Also note that debris in the threads of a fastener can greatly increase the chances of galling. Always use clean parts. Use Extra Care With Lock Nuts Nylon insert lock nuts and, especially, prevailing torque nuts generate a large amount of friction and heat during installation. If you are experiencing galling problems, slow down installation speed or consider a different locking mechanism. If a Fastener Begins to Bind: STOP If a fastener begins to bind before you are actually tightening it down, stop immediately. Wait a minute or two to allow any heat to dissipate and then back the fastener off. Inspect the threads for damage and try again with a new nut. Anti-seize thread lubricants An anti-seize lubricant can be very effective in preventing galling. Bolt with damaged threads Do not use fasteners with damaged or dirty threads. Nylon insert lock nut Stainless nylon insert lock nuts are especially prone to galling. Why Fasteners Gall Why Are Stainless Bolts Prone to Galling? Stainless, aluminum, and titanium fasteners form thin protective oxide films on their exposed surfaces that prevent corrosion. In addition, this coating reduces friction and prevents direct metal to metal contact during fastening. The protective oxide film can be rubbed or scraped off under the pressure and movement of the fastener being tightened. When this happens these relatively soft metals come into direct contact. Friction increases and the chance of galling increases significantly. What Is Actually Happening? Thread surfaces have microscopic high points that can rub together during fastening. In most cases this does not present a problem as the points slide over each other without damage. Under certain conditions however, the surfaces will not slide past each other. The high points will then shear and lock together, greatly increasing friction and heat. As tightening continues the increased pressure results in more material being sheared off the threads. This cycle continues with even more shearing and locking until the threads are destroyed and the fastener will no longer turn in either direction. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted March 13, 2018 Share Posted March 13, 2018 Brandon, you should be able to buy CRES allthread and make some, also look at Fastenal and even Gary's favorite, Amazon. Don't over look https://www.mcmaster.com/# Thing is you may have to buy in "lots of". I bought my bed carriage bolts (50), nuts (50) and nutserts (10) in the lots noted. Dave ---- Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 13, 2018 Share Posted March 13, 2018 Haven't found 430's on the Bolt Depot, yet, but did find the following. Looks like lubrication is highly recommended with stainless. What is Thread Galling? Thread galling occurs during installation when pressure and friction cause bolt threads to seize to the threads of a nut or tapped hole. It is also known as "cold welding". Once a fastener has seized up from galling it is typically impossible to remove without cutting the bolt or splitting the nut. What Bolts Are Susceptible To Galling? Galling is most often seen in stainless steel (especially when using lock nuts), aluminum, and titanium. Fasteners with damaged threads and fine threads are particularly prone to galling. Hardened steel bolts, especially when zinc plated, rarely gall. What Can I Do to Prevent Galling? Slow Down Installation Speed Because heat generated by friction is a contributing factor in galling, slowing down the installation speed can prevent galling. It is recommended that power tools not be used for the installation of stainless steel or other fasteners prone to galling. This is especially important when using nylon insert lock nuts as these nuts significantly increase the chance of galling. Don't Use Bolts to Pull Joints Together Bolts are not designed to pull together a joint or force materials into position. Doing so drastically increases the chance of galling. The materials being bolted should already be in place so the nut can be spun down by hand until the final tightening. If necessary, use clamps to hold the joint together during bolting. Use a Lubricant Special anti-seizing or anti-galling lubricants can be used to dramatically reduce the chance of galling. Examples include MRO Solutions 1000 Antiseize, Permatex® Anti-Seize Lubricant, Finish Line™ Anti-Seize Assembly Lube and USS Ultra Tef-Gel®. Even a standard lubricant, such as WD-40®, can help reduce friction and prevent galling. Some nuts are available with a waxed finish to reduce the risk of galling. Avoid Damaged or Dirty Threads Check for damage to the threads of each bolt, especially bolts with fine thread. You should be able to put a standard nut on a bolt by hand. If not, it may indicate dented or damaged threads. Also note that debris in the threads of a fastener can greatly increase the chances of galling. Always use clean parts. Use Extra Care With Lock Nuts Nylon insert lock nuts and, especially, prevailing torque nuts generate a large amount of friction and heat during installation. If you are experiencing galling problems, slow down installation speed or consider a different locking mechanism. If a Fastener Begins to Bind: STOP If a fastener begins to bind before you are actually tightening it down, stop immediately. Wait a minute or two to allow any heat to dissipate and then back the fastener off. Inspect the threads for damage and try again with a new nut. Anti-seize thread lubricants An anti-seize lubricant can be very effective in preventing galling. Bolt with damaged threads Do not use fasteners with damaged or dirty threads. Nylon insert lock nut Stainless nylon insert lock nuts are especially prone to galling. Why Fasteners Gall Why Are Stainless Bolts Prone to Galling? Stainless, aluminum, and titanium fasteners form thin protective oxide films on their exposed surfaces that prevent corrosion. In addition, this coating reduces friction and prevents direct metal to metal contact during fastening. The protective oxide film can be rubbed or scraped off under the pressure and movement of the fastener being tightened. When this happens these relatively soft metals come into direct contact. Friction increases and the chance of galling increases significantly. What Is Actually Happening? Thread surfaces have microscopic high points that can rub together during fastening. In most cases this does not present a problem as the points slide over each other without damage. Under certain conditions however, the surfaces will not slide past each other. The high points will then shear and lock together, greatly increasing friction and heat. As tightening continues the increased pressure results in more material being sheared off the threads. This cycle continues with even more shearing and locking until the threads are destroyed and the fastener will no longer turn in either direction. Oh, you absolutely need lubricant when assembling/disassmbling stainless fasteners. Nickel based antiseize seems to make sense here. But not so much when threading into something like cast iron or brass. Stainless on stainless will gall and get very hot. Sometimes you won't be able to get the nut off, and then you either have to break it or cut it free. Pretty sure both Bill and I have mentioned this before. I think this is why people say stainless is 'gummy' Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 13, 2018 Share Posted March 13, 2018 Oh, you absolutely need lubricant when assembling/disassmbling stainless fasteners. Nickel based antiseize seems to make sense here. But not so much when threading into something like cast iron or brass. Stainless on stainless will gall and get very hot. Sometimes you won't be able to get the nut off, and then you either have to break it or cut it free. Pretty sure both Bill and I have mentioned this before. I think this is why people say stainless is 'gummy' Dave - Good point. And we have a Grainger's, which is not far from Brandon. Jim - Yes, I think lubrication has been mentioned, but I was afraid it had gotten lost in the shuffle so wanted to highlight it to Brandon. Link to comment Share on other sites More sharing options...
Recommended Posts