what is the difference between 18-8, 304 and 316 stainless steel bolts and nut [Stainless Steel Nut]
Generally people ask the question, what is the difference between 18-8, 304 and 316 stainless steel bolts and nut, for the answer to this question, you must first need to know some basic information about stainless steel bolts and nuts. "Stainless Steel" is the general name for a large family or group of alloy steels that contain at least 10.5% chromium as part of China Stainless Steel Gear Manufacturers their composition. At and above this level of chromium, a complex chrome-oxide surface layer forms that prevents further oxygen atoms from penetrating into the steel and thus protects the iron in the matrix from rusting and corrosion in a bolt or a nut.This layer is what makes the bolt "stainless."
Higher levels of chromium and the addition of other alloying elements such as molybdenum and nickel enhance this protective barrier and further improve the corrosion resistance of the stainless steel the popular grades in hex bolts and nuts, foundation bolts, anchor bolts, bolts & nuts, Nut & bolts in stainless steel being SS 316 and S 316L and 316S31. There are many different types of stainless steel fasteners or bolts and nuts, but by far the most popular and widely used are the 300 series stainless steels, also known as the austenitic stainless steels.The 300 series designation contains many different compositions of alloy steel bolts and nuts and fasteners (303, 304, 304L, 305, 316, 321, 347, 316S31, 316Letc.) but the common factors among them are: Their carbon content is generally held to a maximum of 0.08% They (generally) have 18% chromium They (generally) have 8% nickel They are non-magnetic They cannot be hardened by heat treatment They can be hardened by cold working the material ("work hardening.") By far the second most popular type of stainless steel bolt and nuts or fasteners or screws, after Type 304, is Type 316.
In Type 316 stainless steel bolt and nut & washers or SS 316 Nut and bolt, the chromium content is lowered from 18% to 16%, however, the nickel content is raised to 10% and 2% molybdenum is added to the mixture. This change in the chromium/nickel ratio and the addition of the molybdenum increases the resistance to chlorides. This is why Type 316 stainless steel bolt and nut is often used in more corrosive environments where the material will be exposed to chemical, solvent, or salt water corrosion and makes it the preferred material for marine construction. The recent use of 316S31 grade bolt and nut & washers in marine applications and sewage plants and off shore applications in the middle east has enhanced the performance of the bolt and has given a longer life to the products life cycle.
Higher levels of chromium and the addition of other alloying elements such as molybdenum and nickel enhance this protective barrier and further improve the corrosion resistance of the stainless steel the popular grades in hex bolts and nuts, foundation bolts, anchor bolts, bolts & nuts, Nut & bolts in stainless steel being SS 316 and S 316L and 316S31. There are many different types of stainless steel fasteners or bolts and nuts, but by far the most popular and widely used are the 300 series stainless steels, also known as the austenitic stainless steels.The 300 series designation contains many different compositions of alloy steel bolts and nuts and fasteners (303, 304, 304L, 305, 316, 321, 347, 316S31, 316Letc.) but the common factors among them are: Their carbon content is generally held to a maximum of 0.08% They (generally) have 18% chromium They (generally) have 8% nickel They are non-magnetic They cannot be hardened by heat treatment They can be hardened by cold working the material ("work hardening.") By far the second most popular type of stainless steel bolt and nuts or fasteners or screws, after Type 304, is Type 316.
In Type 316 stainless steel bolt and nut & washers or SS 316 Nut and bolt, the chromium content is lowered from 18% to 16%, however, the nickel content is raised to 10% and 2% molybdenum is added to the mixture. This change in the chromium/nickel ratio and the addition of the molybdenum increases the resistance to chlorides. This is why Type 316 stainless steel bolt and nut is often used in more corrosive environments where the material will be exposed to chemical, solvent, or salt water corrosion and makes it the preferred material for marine construction. The recent use of 316S31 grade bolt and nut & washers in marine applications and sewage plants and off shore applications in the middle east has enhanced the performance of the bolt and has given a longer life to the products life cycle.
The grade of metal used to make them is in general far higher [Stainless Steel Nut]
When it comes choosing a screw for a job you always need to ensure that you have the right one. This sounds so simple yet so many people run in to problems by not doing so, and nowhere is the choice of machine screw more vital than when it comes to using machine screws. Make no mistake whilst you may "Get by" by using a self tapping screw that is slightly too short or too wide for the job, do this with a machine screw and it will end in China Shock Absorber Piston Manufacturers tears. Firstly machine screws are made with far more precision and in general feature finer threads than self tappers as an example.
The grade of metal used to make them is in general far higher and accordingly the screw heads are far harder wearing as machine screws are designed for use in situations where they may need to be repeatedly fastened and unfastened. In outside situations where they are exposed to the whether then they are often made of stainless steel, a typical use being in the railway industry where they may be used to hold an electrical panel shut. Care does need to be taken when using them, and the main danger comes from over tightening them, as if they are made of a harder metal than the metal they are being screwed in to then they can easily strip the thread of the item they are going in to. This can be a major problem and in the case of using them to fasten a control panel as an example, could result in the panel having to go away to have a new thread put in.
Or worst case you could find that you cannot undo the panel as you have crossed the thread, or that you simply cannot tighten the screw up as the thread has been stripped. Machine screws should never be used instead of self tapping screws as they are not designed to do the same job, and vice versa. Machine screws are often designed to screw in to a nut or caged nut in a panel. The right thread choice and screw length are vital - Simply put if you do not have the right one to hand for the job then go away and get some more. Use the wrong ones and a 10p screw could write off a 300+ control panel. They are ideal when used as a precision fixing that needs to be easily undone and then redone up again on a repeated basis.
The grade of metal used to make them is in general far higher and accordingly the screw heads are far harder wearing as machine screws are designed for use in situations where they may need to be repeatedly fastened and unfastened. In outside situations where they are exposed to the whether then they are often made of stainless steel, a typical use being in the railway industry where they may be used to hold an electrical panel shut. Care does need to be taken when using them, and the main danger comes from over tightening them, as if they are made of a harder metal than the metal they are being screwed in to then they can easily strip the thread of the item they are going in to. This can be a major problem and in the case of using them to fasten a control panel as an example, could result in the panel having to go away to have a new thread put in.
Or worst case you could find that you cannot undo the panel as you have crossed the thread, or that you simply cannot tighten the screw up as the thread has been stripped. Machine screws should never be used instead of self tapping screws as they are not designed to do the same job, and vice versa. Machine screws are often designed to screw in to a nut or caged nut in a panel. The right thread choice and screw length are vital - Simply put if you do not have the right one to hand for the job then go away and get some more. Use the wrong ones and a 10p screw could write off a 300+ control panel. They are ideal when used as a precision fixing that needs to be easily undone and then redone up again on a repeated basis.
