Nonmagnetic stainless steel

The sample disc is contained in a chamber formed from two nonmagnetic stainless steel parts, base and chamber cover. The vapor escapes from the chamber through a small hole (of accurately determined area and thickness) directly under and about 4 mm. from the collection surface. The collection surface, which is ground flat and polished, is the bottom surface of a well containing the coolant which is normally liquid nitrogen. This glass apparatus was fabricated from a section of standard... 

An overall view of the basic tensile-test apparatus is shown in Fig. 1. To eliminate any interaction between the 12-T magnet and the surrounding room-temperature structure, the entire load frame of the tester is fabricated from nonmagnetic stainless steel. The crosshead, shown in the fully raised position in Fig. 1, is supported by two 5.3-m-long, 100-mm-diameter columns. It is raised and lowered by two hydraulic pistons and can be hydraulically clamped to the columns at any position. The column height was made sufficient to allow the cryogenic structure to be raised above the cryostat, the cryostat to be removed, and the structure then lowered back down for the sample to be changed. 

The mass of the tested explosive charge depends upon the size of the coils and the type of its protection from the blast damage. Thus, for instance, wfren the diameter of the coils is 500 mm, and 10 mm thick nonmagnetic stainless steel casing is used for protection of the coil assembly, then up to 200 g of explosive can be detonated. 

Nonmagnetic drill collars are manufactured from various alloys, although the most common are Monel K500 (approximately 68% nickel, 28% copper with some iron and manganese, and 316L austenitic stainless steel). A stainless steel with the composition of 0.06% carbon, 0.50% silicon, 17-19% manganese, less than 3.50% nickel, 12% chromium, and 1.15% molybdenum, with mechanical properties of 110 to 115 Ksi tensile strength is also used. 

Describes certain types of stainless steels and other metals that consist of nonmagnetic iron containing face-centered cubes of carbon or other elements in solid solution. 

High-carbon austenitic structures can be preserved at ambient temperatures if the iron is alloyed with sufficient nickel or manganese, since these metals form solid solutions with 7-Fe but not with a-Fe. If over 11% chromium is also present, we have a typical austenitic stainless steel. Such steels are corrosion resistant, nonmagnetic, and of satisfactory hardness, but, because the a-Fe 7-Fe transition is no longer possible, they cannot be hardened further by heat treatment. Figure 5.9 summarizes these observations. 

If you require metal components on your vacuum system, select metals with low gas permeation, such as 300 series stainless steel. It is nonmagnetic and, like glass, is a poor conductor of heat and electricity. Stainless steel, also like glass, is relatively nonreactive, and therefore is less likely to rust or be affected by chemicals. If welding the stainless steel is required, select 304L stainless steel, which is low in carbon. Otherwise, at welding temperatures the carbon will combine with the chromium (within the stainless steel) to form chromium carbide and the corrosion protection of the chromium will be lost. Type 303 stainless steel should not be used for vacuum work because it contains selenium, which has a high vapor pressure. 

Failure Investigation. The clamp was nonmagnetic and the stamped identification on the side of the U-shaped shells indicated that they were fabricated from forged 304 austenitic stainless steel. Visual examination of the fracture surfaces revealed they were entirely brittle and exhibited a very coarse fracture morphology. Liquid penetrant inspection revealed the presence of additional cracks in the fractured half of the clamp. There was no cracking present in the high-strength steel fasteners. 

Stainless steels are in a special class, differing from other steels in being nonmagnetic and essentially free from rusting and corrosion. A typical stainless steel (type 316) contains 17 percent chromium, 12 percent nickel, and 3 percent molybdenum. The chemical resistance of stainless steel makes it very attractive for many purposes, but its cost and the difficulty of machining it limit its use somewhat. It can be silver-soldered or welded soft soldering is difficult. 

This family of stainless accounts for the widest usage of all the stainless steels. These materials are nonmagnetic, have face-centered cubic structures, and possess mechanical properties similar to the mild steels, but with better formability. The AISI designation system identified the most common of these alloys with numbers beginning with 300 and resulted in the term 300 series stainless. Table 3 lists the chemical analyses of some standard austenitic stainless steels and compares them to a few materials from other families of materials. 

Austenitic stainless steels are nonmagnetic in the annealed condition. 

Weak Attraction Stainless Steels cold worked 302 and 304, 308 filler metal Monel (becomes nonmagnetic in boiling water)... 

Magnetic properties of some metals may change with their mechanical history. For example, 302 and 304 stainless steels are nonmagnetic in the annealed (soft) condition, but become increasingly magnetic as they are cold worked. 

Nonmagnetic. These are the 300 series stainless steels. They contain between 17% to 30% chromium and substantial amounts of nickel. Type 304 (18% chrome, 8% nickel) is the general-purprose alloy of this group. 

Carbon steel pipe will have a brownish or rusty color. Stainless piping will resist atmospheric oxidation and maintain a dull silver color. Check the stainless piping with a magnet. Chrome-nickel alloys (300 series) generally will be nonmagnetic, while chrome stainless steel (400 series) will be magnetic. 

Austenitic stainless steels Stainless steels with an specific type of nonmagnetic crystal structure. 

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