which kind of steel is called gigh grade alloy in USA and which kind is low grade? is 4140 called high grade steel?
regards
yes

That's a rather nebulous term ! The typical steel for guns is 4140.Sometimes 4130 or 4150 are used.4140 is used for both receivers and barrels .

Just because it's labeled 4140 etc doesn't mean it's high quality.

The way the steel is processed and the purity of the metals thrown into the melt is important. Some of the base steel may be from the scrap yard clouding the mix as well.

The type of furnace used also determines the quality of the finished product.

There are many different grades of the same alloy.

At Castle steel they show in their alloy section:
commercial quality
bearing quality
aircraft quality
premium quality

If you're looking to build something where safety is paramount I'd make sure and get the certification of the steel that it meets the level of quality needed.

John Benjamin is a barrel maker in Portland, that I see at machine auctions in Seattle.

He tells me that he controls 4140 purchases through the mil-spec.

I have allot of surplus 4140 at my house. I don't like to use it, because if it ever gets hot for a second, it hardens, the tool gets dull, and then it really gets hard. I wind up ordering another carbide drill. The way to drill through it is in continuous bath of coolant.

Don't the best steels come from Sweden?
That's what our 9th grade shop teacher told us in 1965.

Hi
well sure Sweden is home of some of finest steel in the world.my real question was about steel composition in high and low alloy not really about the degree of purity. for exemple 4140 with only 1to 1,5 percent chrom is usually called low grade alloy and from 5% upward is called high ally, but i see many makers using the name high grade alloy for 4140 and was confused,
regards
yes

quote:

Don't the best steels come from Sweden?

That's like saying the best food in the world or the best looking women or the worst drivers or the fattest people ... horse-shit all. The best could be made in outer Mongolia if the crew making it wants it that way.

The reason that the " best steels come from Sweden " that the iron ore there had very low amounts of sulfur and phosphorous.That was very significant in the past as these two elements were undesirable. Today steel is mostly recycled material rather from ore.
Unfortunately today much of the steel from China and India is substandard with material not to specification and containing significant amounts of trace elements such as copper.

There are gross categories of steel, like ASTM steels which are used in buildings, SAE Steels which are used to make machined stuff, and tool steels which, well, you get the picture. Quality control, strength, etc. vary greatly between the gross categories, and the better you get, the more options there are (degassed, normalized, whatever). I think most gun parts are made from SAE type steels. Thats a quick answer without looking anything up. SAE Steels are way better than ASTM, and tool steels are better yet.

quote:

Originally posted by Macifej:

quote:

Don't the best steels come from Sweden?

That's like saying the best food in the world or the best looking women or the worst drivers or the fattest people ... horse-shit all. The best could be made in outer Mongolia if the crew making it wants it that way.

Macifej,
My point of view is from a 1900x1200 View Sonic.