High-Carbon, Low-Alloy Steels

High Speed Steels. Toward the latter part of the nineteenth century, a new he at-treatment technique for tool steels was developed in the United States (3,17) that enabled increased metal removal rates and cutting speeds. This material was termed high speed steel (HSS) because it nearly doubled the then maximum cutting speeds of carbon—low alloy steels. Cemented carbides and ceramics have since surpassed the cutting speed capabiUties of HSS by 5—15 times. 

It must always be remembered that diffusion coatings are produced by a form of heat treatment and that, with the exception of low-temperature zinc diffusion (sherardising), the treated ferrous materials are usually in the annealed condition. Whenever the mechanical properties of the parts must be restored to their original level, a subsequent heat treatment is necessary . This does not as a rule present any difficulty with chromised or boronised steels. In order to prevent undue distortion and internal stresses during treatment and subsequent hardening, it is recommended that high-carbon and alloy steels should be processed in the normalised condition. 

A 690 High-strength low-alloy steel H-piles and sheet piling Ni, Cu, Si Structural-quality H-pills and sheet piling Corrosion resistance two to three times greater than that of carbon steel in the splash zone of marine marine structures Dock walls, sea walls Bulkheads, excavations and similar structures exposed to seawater... 

A 871 High-strength low-alloy steel with atmospheric corrosion resistance V, Nb, Ti Cu, Mo, Cr As-rolled plate < 35 mm in thickness Atmosperic-corrosion resistance four times that of carbon Tubular structures and poles... 

In most instances, corrosion test methods for plain carbon steels, high-strength low-alloy steels, and alloy steels do not differ greatly. Therefore, these steels are grouped together for the purposes of this chapter. (Alloy steels here refers to heat treatable constructional and automotive steels, and does not include the stainless steels or other high alloys.) There are some differences in the corrosion test methods used for different mill products of this group of steels, and these will be discussed. The steels covered in this chapter are defined below. 

Steels for structural use are classified as carbon steels, high-strength low-alloy steels, and alloy steels. For design purposes, these steels can be assumed to have a density of 7.85 g/cm, a modulus of elasticity of 210 GPa, and a Poisson s ratio of 0.3. Carbon steels are classified based on the percentage of carbon. Mild carbon steels (0.15-0.29 % C) with yield points in the range of 220-250 MPa and tensile strengths of 400-500 MPa are the most common structural carbon steels. Typically, an increase in carbon percent raises the yield point and increases hardness, but reduces ductility and makes welding more difficult. These drawbacks can be minimized by heat treatments. 

Most metals and combination of metals weldable, including low to high carbon and alloy steels, aluminum, titanium, copper, refractory and precious metals. 

Compositions of Four Plain Low-Carbon Steels and Three High-Strength, Low-Alloy Steels... 

Plain Carbon and Low Alloy Steels. For the purposes herein plain carbon and low alloy steels include those containing up to 10% chromium and 1.5% molybdenum, plus small amounts of other alloying elements. These steels are generally cheaper and easier to fabricate than the more highly alloyed steels, and are the most widely used class of alloys within their serviceable temperature range. Figure 7 shows relaxation strengths of these steels and some nickel-base alloys at elevated temperatures (34). 

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