Technical Requirements for Choosing Raw Material of Throat Hoop

Laryngeal hoop is a mechanical base, which is in great demand. Generally, it does not need to consider the adverse environmental or other risk conditions caused by temperature. Commonly used data are carbon steel, low alloy steel and non-ferrous metals. However, in specific occasions, the throat hoop information needs serious corrosion or high strength conditions. Many stainless steels and ultra-high strength stainless steels emerge as the times require.

This article briefly introduces the excellent stainless steel for throat hoop production. Most stainless steel materials can be made into steel wire or bar for throat hoop production, including austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, stack hardening stainless steel.

Selection criteria:

The selection of stainless steel materials is mainly considered from the following five aspects. 1. Requirements for mechanical function, especially strength of throat hoop data.

2. The requirement of working conditions on the anti-corrosion function of data.

3. Requirements of operating temperature for heat-resistant function (high temperature strength, anti-oxidation function) of data.

4. Production technology is facing the demand of data processing function.

5. Other aspects, such as weight, quotation and acquisition, should be considered.

After all these five aspects are considered and summarized, the trademarks, types, specifications and data specifications for choosing throat hoops are determined.

Austenitic stainless steel

Commonly used trademarks are 302, 303, 304 and 305, namely the so-called "18-8" austenitic stainless steel trademarks. Both corrosion resistance and mechanical function are similar. The starting point of selection is the technical method of throat hoop production, which depends on the specification and shape of throat hoop, together with the quantity of throat hoop production.

Type 302 is used for selecting machined bolts and tapping bolts.

In order to improve the cutting function of type 303 stainless steel, a small amount of sulphur is added to type 303 stainless steel, which is used to process nuts with bars.

Type 304 is suitable for processing throat hoops with hot heading technology, such as long standard bolts and large diameter bolts, which can exceed the plan of cold heading technology.

Model 305 is suitable for processing throat hoops with cold heading technology, such as cold formed nuts and hexagonal bolts.

Types 309 and 310 have higher Cr and Ni contents than those of type 18-8 stainless steel. They are suitable for throat hoops operating at high temperatures.

Both 316 and 317 are rich in Mo, so their high temperature strength and corrosion resistance are higher than those of 18-8 stainless steel.

Types 321 and 347, 321 and 347 are rich in relatively stable alloying elements Ti, 347 are rich in Nb, and then the function of intergranular corrosion resistance of data is carried out. It is suitable for throat hoops that are not annealed after welding or are in service at 420-1013 C.

Ferritic stainless steel

430 type general chromium steel has better corrosion resistance and heat resistance than 410 type. It has magnetism, but it can not be strengthened by heat treatment. It is suitable for stainless steel throat hoop with slightly higher corrosion resistance and heat resistance and general strength requirement.

Martensitic stainless steel

Model 410 and 416 can be hardened by heat treatment with hardness ranging from 35 to 45 HRC. They have excellent machinability and are used for heat-resistant and corrosion-resistant throat hoops for general use. Model 416 has a slightly higher sulfur content and is a free-cutting stainless steel.

Model 420, with sulphur content (>0.15%) and mechanical function, can be strengthened by heat treatment. Its maximum hardness is 53-58HRC. It is used for throat hoops with high strength.

Stack hardening stainless steel

17-4PH, PH15-7Mo, which can obtain higher strength than the general 18-8 stainless steel, are used for high strength, corrosion resistant stainless steel throat hoops.

A-286, a non-standard stainless steel, has higher corrosion resistance than the commonly used 18-8 stainless steel, and still has excellent mechanical function when the temperature increases. It can be used as a high strength, heat-resistant and corrosion-resistant throat hoop, and can be used to 650-700 C.