Shock resisting steel

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Shock resisting steels are a class of tool steels designed to resist breakage by shock. Under the AISI classification system there are seven types, labeled S1 to S7.

Contents

Overview

Shock resisting steels are designed to have high impact resistance (toughness), along with other properties such as strength, hardness. Silicon is a common addition to this class of steels, as it provides tempering resistance, and increases toughness. [1]

Applications for shock resisting steels includes springs, as well as chisels, dies for forging, and punches. [1] S2 steel is also used to make Ball bearings for the mining industry. [2] They are also used for screwdrivers and driver bits. [3]

Type C  % Si  % V  % Cr  % Mn  % Ni  % Mo  % W  %
S1 (UNS T41901) [1] [3] [lower-alpha 1] 0.40-0.550.15-1.200.15-0.301.00-1.800.10-0.40<0.30<0.501.50-3.00
S2 (UNS T41902) [1] [3] 0.40-0.550.90-1.20<0.50-0.30-0.50<0.300.30-0.60-
S3 [4] 0.502.00-0.74---1.00
S4 (UNS T41904) [1]  ? ~0.4-0.651.75-2.250.350.350.60-0.90-
S5 (UNS T41905) [1] [3] 0.50-0.651.75-2.25<0.35<0.500.60-1.00-0.20-1.35-
S6 (UNS T41906) [3] 0.40-0.502.00-2.500.20-0.401.20-1.501.20-1.50-0.30-0.50-
S7 (UNS T41907) [1] [3] 0.45-0.550.20-1.000.20-0.30 [lower-alpha 2] 3.00-3.500.20-0.90-1.30-1.80-
  1. Commonly known as 'tungsten chisel steel'
  2. May be omitted

SVCM

SVCM steel is kind of shock resisting steel. [5] SVCM steel is an alloy of carbon, silicon, chromium, magnesium, nickel, molybdenum and lead. [6] SVCM+ in addition is quenched and tempered achieving a high hardness (HRC 59). [6] SCVM+ has better torsional properties than chromium-vanadium steel (Cr-V). [7]

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Metallurgy Domain of materials science that studies the physical and chemical behavior of metals

Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are called alloys. Metallurgy encompasses both the science and the technology of metals; that is, the way in which science is applied to the production of metals, and the engineering of metal components used in products for both consumers and manufacturers. Metallurgy is distinct from the craft of metalworking. Metalworking relies on metallurgy in a similar manner to how medicine relies on medical science for technical advancement. A specialist practitioner of metallurgy is known as a metallurgist.

Cast iron Iron-carbon alloys with a carbon content more than 2%.

Cast iron is a group of iron-carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its colour when fractured: white cast iron has carbide impurities which allow cracks to pass straight through, grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks, and ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing.

High-strength low-alloy steel

High-strength low-alloy steel (HSLA) is a type of alloy steel that provides better mechanical properties or greater resistance to corrosion than carbon steel. HSLA steels vary from other steels in that they are not made to meet a specific chemical composition but rather specific mechanical properties. They have a carbon content between 0.05 and 0.25% to retain formability and weldability. Other alloying elements include up to 2.0% manganese and small quantities of copper, nickel, niobium, nitrogen, vanadium, chromium, molybdenum, titanium, calcium, rare-earth elements, or zirconium. Copper, titanium, vanadium, and niobium are added for strengthening purposes. These elements are intended to alter the microstructure of carbon steels, which is usually a ferrite-pearlite aggregate, to produce a very fine dispersion of alloy carbides in an almost pure ferrite matrix. This eliminates the toughness-reducing effect of a pearlitic volume fraction yet maintains and increases the material's strength by refining the grain size, which in the case of ferrite increases yield strength by 50% for every halving of the mean grain diameter. Precipitation strengthening plays a minor role, too. Their yield strengths can be anywhere between 250–590 megapascals (36,000–86,000 psi). Because of their higher strength and toughness HSLA steels usually require 25 to 30% more power to form, as compared to carbon steels.

Stellite is a range of cobalt-chromium alloys designed for wear resistance. The alloys may also contain tungsten or molybdenum and a small but important amount of carbon.

Carbon steel Steel in which the main interstitial alloying constituent is carbon

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Tool steel

Tool steel refers to a variety of carbon steel and alloy steel that are particularly well-suited to be made into tools. Their suitability comes from their distinctive hardness, resistance to abrasion and deformation, and their ability to hold a cutting edge at elevated temperatures. As a result, tool steels are suited for use in the shaping of other materials. With a carbon content between 0.5% and 1.5%, tool steels are manufactured under carefully controlled conditions to produce the required quality. The presence of carbides in their matrix plays the dominant role in the qualities of tool steel. The four major alloying elements that form carbides in tool steel are: tungsten, chromium, vanadium and molybdenum. The rate of dissolution of the different carbides into the austenite form of the iron determines the high-temperature performance of steel. Proper heat treatment of these steels is important for adequate performance. The manganese content is often kept low to minimize the possibility of cracking during water quenching.

High-speed steel Subset of tool steels

High-speed steel is a subset of tool steels, commonly used as cutting tool material.

Tempering (metallurgy) Process of heat treating used to increase toughness of iron-based alloys

Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, while springs are tempered at much higher temperatures.

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SAE steel grades

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Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The difference between the two is disputed. Smith and Hashemi define the difference at 4.0%, while Degarmo, et al., define it at 8.0%. Most commonly, the phrase "alloy steel" refers to low-alloy steels.

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Mangalloy Alloy steel containing around 13% manganese

Mangalloy, also called manganese steel or Hadfield steel, is an alloy steel containing an average of around 13% manganese. Mangalloy is known for its high impact strength and resistance to abrasion once in its work-hardened state.

Caldie is a chromium-molybdenum-vanadium alloyed tool steel manufactured by Uddeholms AB. It is intended for cold work processes, such as blanking and piercing, applied to difficult materials such as advanced high strength steel, where compressive strength and chipping and cracking resistance are important.

HY-80 Alloy steel

HY-80 is a high-tensile, high yield strength, low alloy steel. It was developed for use in naval applications, specifically the development of pressure hulls for the US nuclear submarine program and is still currently used in many naval applications. It is valued for its strength to weight ratio.

DIN 1.2344 tool steel is a tool steel grade standardised for hot working. The main feature of this grade is the combination of alloyed elements of chromium, molybdenum and vanadium, Cr-Mo-V, which provides a high wear resistance to thermal shock. It is well known as for its great strength, and heat resistance. It is heavily used for die casting in the cold heading field. The presence of high vanadium in DIN 1.2344 can handle the abrasion at both low and high temperatures. It always provides a uniform and high level of machinability. This tool steel is mostly used for aluminum, magnesium and zinc die casting.

USAF-96 is a high-strength, high-performance, low-alloy, low-cost steel, developed for new generation of bunker buster type bombs, e.g. the Massive Ordnance Penetrator and the improved version of the GBU-28 bomb known as EGBU-28. It was developed by the US Air Force at the Eglin Air Force Munitions Directorate. It uses only materials domestic to the USA. In particular it requires no tungsten.

References

  1. 1 2 3 4 5 6 7 Isakov, Edmund (2007), Cutting Data for Turning of Steel, Industrial Press Inc., Chapter 1 § 1.5.2 Shock-resisting tool steels. pp.82-84
  2. Materials Selection for the Minerals Industry, Metallurgical Society of AIME, 1977, p. 69
  3. 1 2 3 4 5 6 "Tool Steels - Shock-Resisting Tool Steels", www.azom.com
  4. Davis, Joseph R., ed. (1995), ASM Specialty Handbook: Tool Materials, p.123, Table 2.
  5. "What Our Tools Are Made Out of". Olsa Tools.
  6. 1 2 "Screwdrivers | Hand Tools | Draper Tools". www.drapertools.com. Made by blending carbon, silicon, magnesium, nickel, chromium, molybdenum and lead to create a metal featuring a host of qualities including high strength and ductility
  7. "Common materials for hand tools:Carbon steel & Chromium-vanadium steel". August 14, 2018.