不锈钢枪管的讨论 410/416/416R

Snowbird · 发表于 2015-3-14 07:45

看到网上这个帖子，和大家分享讨论一下。
http://www.m4carbine.net/showthr ... -410-vs-416-vs-416R

Why stainless steel?

There are two main advantages to a stainless steel barrels. First is a higher corrosion resistance when compared to an unlined, uncoated standard carbon steel barrel. However, don't be fooled into thinking stainless steel barrels are rust proof... They are not. The 400-series stainless steels (also known as martensitic stainless) used for barrel making are more resistant to corrosion than carbon steel, but will still rust if neglected. In fact, a chrome lined carbon steel barrel with a well oiled parkerized finish will usually resist rust better than a bare stainless steel barrel due to the finishes applied to the inside and outside of the barrel. Likewise, melonite treated carbon steel is much more rust resistant than any of the 400-series stainless steels.

The second advantage to stainless steel vs plain carbon steel as it relates to barrels is the "toughness" of the metal. Stainless steel is more resistant to heat and abrasion than plain carbon steel. All else being equal, a stainless steel barrel should theoretically experience less throat erosion than a plain carbon steel barrel, given identical firing schedules. This does not mean that stainless steel will resist throat erosion better than a chrome lined carbon steel barrel - it will not. Chromium is much tougher than 400-series stainless.

为嘛要不锈钢呢？

一是抗腐蚀。秒搞错，不锈钢也会生锈，a chrome lined carbon steel比普通不锈钢枪管还耐锈, melonite treatd carbon steel比任何400系的不锈钢枪管都耐锈。抗锈，上油是王道。

二是扛磨损。

（不懂材料学的术语，不知瞎翻译的对不对，求高手指正）

Snowbird · 发表于 2015-3-14 07:47

At this point many of you are probably thinking, "What about accuracy?" Truth is, as far as I can tell and from what I have gathered from the barrel makers themselves and shooters much more experienced than I, is that accuracy boils down to the barrel making process itself, not the host material. You can make an inaccurate barrel out of stainless steel just as easily as you can make an accurate barrel out of bare carbon steel, however most high end barrels are likely going to made from stainless steel for longer life compared to bare carbon steel. The only notable difference as far as accuracy is concerned is whether the barrel is chrome lined or not. In theory, chrome lining should reduce the accuracy of the host barrel by creating slight variances in bore dimensions. How much depends on how uniformly the chrome lining was applied. That said, FN makes some impressive accuracy claims about their chrome lined, cold hammer forged carbon steel SPR bolt-action rifle barrels...

If you still don't know if you want a stainless steel barrel, you probably don't need one and can stop reading this now. A chrome-lined carbon steel barrel will meet the needs of the majority of shooters, and in many instances may even meet specific needs better than a stainless steel barrel. Unfortunately I do not have the time to go into the differences in carbon steels, so If you decide stainless steel is not for you, you will have to do the rest of the research on your own. This would be a good place to start, specifically post #15, quoted below, where aOcake outlines some questions you should ask yourself when deciding between a stainless steel or chrome lined carbon steel barrel.

精度么，嘿嘿。

换句话说，a chrome-lined carbon steel对多数周末射手就足够了。

Snowbird · 发表于 2015-3-14 07:55

Why not stainless steel?

Now that we've established why someone might want to choose a stainless steel barrel, what are some of the reasons they may not? The first and most obvious is because they have determined that a standard carbon steel barrel or a chrome lined carbon steel barrel will meet their needs as well or better than a stainless steel barrel would, and therefore the extra cost of a quality stainless steel barrel is not justified.

Aside from that, there are two main disadvantages to stainless steel barrels. The first is a decreased impact resistance at sub zero temperatures caused by "temper embrittlement" that has the potential to lead to barrel failures. While this is not a common problem, it is still something to consider if you are in a region that frequently sees the mercury drop below 0 degrees Fahrenheit at any time during the year when you may use the rifle. The second disadvantage is created by the addition of sulfur to martensitic stainless steels to make them easier to machine. Higher sulfur content increases the likelihood that the barrel steel could develop "sulphide stringers" which are weak spots in the steel that have the potential to cause barrel failure. I believe this was a contributing factor to the barrel failure problems Tikka was experiencing with their stainless steel barrels a while back.

（这段有意思，比较适合俺这种辩证思维强迫症的）
为嘛不用不锈钢呢？

1、不适合超低温环境（考，不知道明尼苏达算不算超低温，华氏零度每年总会有几天，问题是冷成那样了，就算靶场免费，子弹免费，估计也没人愿意出去打靶啊）

2、有可能布拉布拉。。。

普通枪管的精度损失是渐进的，不锈钢管是恒定+突变的。（这个特性很适合比赛，是优点还是缺点，看个人需求吧）

Snowbird · 发表于 2015-3-14 07:59

好吧，假设你还是想要不锈钢，bling bling的很拉风，那么到底是4XXX或410或416或416R呢？

先看结论
Summary

In conclusion, if you are in the market for a stainless steel rifle barrel I would offer the following recommendations:

Avoid lightweight or thin profile stainless steel barrels. This recommendation is echoed from multiple barrel manufactures due to the potential issues with temper embrittlement in martensitic stainless steels. The thicker walls of a medium, heavy, or bull profile barrel will strengthen the barrel and make up for the shortcomings of 400-series stainless steels as a barrel steel.
Avoid standard 416 stainless steel barrels. 410 and 416R stainless steels both have a lower sulfur content, making them less prone to developing sulphide stringers which may result in catastrophic barrel failure.
If the rifle will never see freezing temperatures, 410 stainless steel will likely be your best option. 410 stainless steel has the lowest sulfur content of the three grades we discussed, and will be the least likely to develop sulphide stringers. Avoiding sub-zero temperatures and using a barrel of adequate thickness should also minimize the temper embrittlement issue.
If the rifle may see freezing temperatures, 416R stainless steel will likely be your best option. 416R stainless steel is rated for use at temperatures as low as -40 degrees Fahrenheit and has a lower sulfur content than standard 416 stainless steel. However, you should still ensure the barrel is of adequate thickness.

再看分解

416R Stainless Steel:

416R is a proprietary steel produced by Crucible specifically designed for rifle barrels. The main difference between 416R and standard 416 stainless steels is the addition of Molybdenum (which is present in 410 but not 416 stainless steels) and a lower sulfur content than 416 stainless steel (but still higher than 410 stainless steel). Crucible also states that barrels made from 416R may be safely used at temperatures as low as -40 degrees Fahrenheit.

416 Stainless Steel:

Grade 416 has the highest machinability of any stainless steel, at about 85% of that of a free-machining carbon steel. As for most other free-machining stainless steels the improvement in machinability is achieved by addition of sulphur which forms manganese sulphide inclusions; this sulphur addition also lowers the corrosion resistance, weldability and formability to below that of its non-free machining equivalent Grade 410.

Grade 416 is sometimes used in the unhardened or hardened and highly tempered condition because of its low cost and ready machinability.

Martensitic stainless steels are optimised for high hardness, and other properties are to some degree compromised. Fabrication must be by methods that allow for poor weldability and usually also allow for a final harden and temper heat treatment. Corrosion resistance is lower than the common austenitic grades, and their useful operating temperature range is limited by their loss of ductility at sub-zero temperatures and loss of strength by over-tempering at elevated temperatures.

416SS.jpg

Corrosion Resistance

Useful resistance to dry atmospheres, fresh water and mild alkalies and acids, but less resistant than the equivalent non-free-machining grades. Less corrosion resistant than the austenitic grades and also less than 17% chromium ferritic alloys such as Grade 430. High sulphur content free machining grades such as 416 are totally unsuitable for marine or other chloride exposure.

Maximum corrosion resistance is achieved in the hardened condition, with a smooth surface finish.

Heat Resistance

Fair resistance to scaling in intermittent service up to 760°C and up to 675°C in continuous service. Not recommended for use in temperatures above the relevant tempering temperature, if maintenance of mechanical properties is important.

Heat Treatment

Full Annealing - Heat to 815-900°C for ½ hour per 25mm of thickness. Cool at 30°C per hour maximum to 600°C and air cool.

Sub-Critical Annealing - Heat to 650-760°C and air cool.

Hardening

Hardened by heating to 925-1010°C, quenching in oil, and tempering to suit the mechanical requirements. See accompanying table.

Note: The tempering range 400-580°C should be avoided, due to poor ductility.

Main Source: http://www.azom.com

Snowbird · 发表于 2015-3-14 08:00

410 Stainless Steel:

Grade 410 is the basic martensitic stainless steel; like most non-stainless steels it can be hardened by a "quench-and-temper" heat treatment. It contains a minimum of 11.5 per cent chromium, just sufficient to give corrosion resistance properties. It achieves maximum corrosion resistance when it has been hardened and tempered and then polished. Grade 410 is a general purpose grade often supplied in the hardened, but still machinable condition, for applications where high strength and moderate heat and corrosion resistance are required.

Martensitic stainless steels are optimised for high hardness, and other properties are to some degree compromised. Fabrication must be by methods that allow for poor weldability and usually the need for a final heat treatment. Corrosion resistance of the martensitic grades is lower than that of the common austenitic grades, and their useful operating temperature range is limited by their loss of ductility at sub-zero temperatures and loss of strength by over-tempering at elevated temperatures.

410SS.jpg

Corrosion Resistance

410 resists dry atmosphere, fresh water, mild alkalies and acids, food, steam and hot gases. Must be hardened for maximum heat and corrosion resistance. Performance is best with a smooth surface finish. Less corrosion resistant than the austenitic grades and also less than 17% chromium ferritic alloys such as Grade 430.

Heat Resistance

Good resistance to scaling up to approximately 650°C, but generally not recommended for use in temperatures between 400 and 580°C, because of the reduction in mechanical properties.
Heat Treatment

Annealing

Full anneal - 815-900°C, slow furnace cool to 600°C and then air cool.

Process Anneal - 650-760°C and air cool.

Hardening

Heat to 925-1010°C, followed by quenching in oil or air. Oil quenching is necessary for heavy sections. Temper, generally within the range 200-400°C, to obtain a wide variety of hardness values and mechanical properties as indicated in the accompanying table.

The tempering range 400-580°C should generally be avoided.

Main Source: http://www.azom.com