HIGH SPEED STEEL — WHY USE IT?

20150728High Speed Steel is a cutting tool material used in drilling, milling, turning, threading, boring, broaching, gear cutting and many other machining operations. High Speed Steel is used for form tools, slitter knives, guillotine knives, parting tools and many other types of cutting tools. High Speed Steel cutting tools are used in all phases of production and are widely used in both machine tools and in portable machine tools.

High Speed Steel is noted for its ability to perform at slow surface speeds, while providing a good surface finish, without chipping or breakage.

High Speed Steel offers reliable toughness. It is commonly used in applications with interrupted cuts and it is notably tougher than carbide and ceramic materials. It also resists chipping in cutting applications.
The toughness allows for Steep Positive Cutting Configurations to be generated. The positive cutting tool configurations demand less horsepower and will lower the level of heat generated during the operation when work hardening is a concern.

High Speed Steel retains good wear resistance in both metal working and wood working applications.

High Speed Steel cutting tools have a sharper cutting edge than carbide cutting tools. The work piece is cut rather than fractured which results in an improved surface finish.

High Speed Steel is used in applications where contamination of scrap is a concern.

To sum up why we want to use it the best answer.

This article comes from Arthur R. Warner Co. edit released

Plastic Mould Steel

The cost of the tooling materials in a mould usually represents only 5–10% of the tool cost. And it is an even smaller part of the total tooling cost.

ZT delivers a series of Plastics Tool Steel and Mould Material Grades for plastics processing which are unmatched in the industry. Our products are manufactured using both conventional and powder metallurgical production techniques. Our close cooperation with tool designers keeps us abreast of the latest demands placed on Plastics Tooling.

Tailored to the needs of the various plastics moulding applications, ZT Plastics Tool Steel and Mould Materials are ideal where high polishability, improved resistance to corrosive and/or abrasive polymers, high thermal conductivity, uniformity and reliability are required.

Our large stock of Tool Steel, Copper-based Alloys, and Holder Steel can be supplied in the form of bars, cut pieces and blocks, supported by custom machining, sawing and grinding services.

From our long experience serving the Plastics Industry we have become very knowledgeable about the sizes, grades and tolerances most frequently required.

This article comes from Böhler Uddeholm Website edit released

New Shock Resistant Cold Work Die Steel Combines Toughness and Wear Resistance

A new shock-resistant cold work die steel with an excellent combination of toughness and wear resistance may be considered for tooling applications such as coining dies, blanking dies, slitter knives, chipper knives and rotary shears, among others.

The new alloy is made by Carpenter’s patented powder metallurgy process known as Micro-Melt Process. Steels made by this method have a refined microstructure with very fine grain size and smaller, more uniformly distributed carbide particles. Eliminated is the segregation found in conventional cast-wrought alloys.

Magnification at 1000 times has verified the fine microstructure of the new, highly alloyed material. The fine carbide distribution, combined with low sulfur content, make dies and tools of this alloy easy to polish. This characteristic makes the alloy an exceptional candidate for coining applications.

Consistent microstructure gives the alloy its good toughness and consistent, reproducible response to heat treatment. Fatigue resistance under repetitive compressive forces has been outstanding.

The alloy balance, particularly nickel, contributes both to toughness and hardness.

Wear resistance comes from the grade’s good hardness coupled with the formation of vanadium, chromium and molybdenum carbides. The steel can be heat treated in salt, vacuum or controlled atmosphere furnaces, and secondary hardened at 950°F (1066°C). Using this treatment, hardness levels up to 61/62 HRC can be achieved with low residual stress in the cold work tools or coining dies made from the material.

Like other Carpenter Micro-Melt alloys, the new CD#1 alloy is more forgiving during heat treatment than conventional tool steels. In addition to predictable response to heat treatment, the alloy remains more dimensionally stable when making a tool, and exhibits less out-of-round distortion after heat treatment. Machinability is also improved in the annealed condition.

The typical analysis of Micro-Melt CD#1 alloy is: carbon 0.70%, manganese 0.40%, silicon 1.00%, chromium 8.25%, molybdenum 1.40%, nickel 1.50%, vanadium 1.00%, nitrogen 0.09%, iron balance.

This new material is available in round, square and flat bar; billet and powder.

This article comes from Carpenter Micro-Melt® edit released

 

Cold Work Tool Steels

Cold work tool steels are essentially high carbon steels, which contain relatively low alloy additions of tungsten, manganese, chromium and molybdenum. These alloy additions increase hardenability, permitting oil quenching with less distortion than with the W series. These are relatively inexpensive steels, and their high carbon content produces adequate wear resistance for short run applications. It is used for all types of blanking and forming dies, gauges, collets, etc.

Cold work tool steels are essentially high carbon steels, which contain relatively low alloy additions of tungsten, manganese, chromium and molybdenum. These alloy additions increase hardenability, permitting oil quenching with less distortion than with the W series. The O series consists of relatively inexpensive steels, and their high carbon content produces adequate wear resistance for short run applications.

In this group of steels, many manufacturers market steels of composition adjusted to meet specific requirements. Undoubtedly, this group of steels can be classed among the largest tonnage used for tool manufacture, the reason being that it is the least expensive; affording a high degree of non-distortion in heat treatment and for short run application cannot really be rivaled. It is used for all types of blanking and forming dies, gauges, collets, etc.

This article comes from Total Materia edit released

 

What Is Stainless Steel and Why Is it Stainless?

20150709In 1913, English metallurgist Harry Brearly, working on a project to improve rifle barrels, accidentally discovered that adding chromium to low carbon steel gives it stain resistance. In addition to iron, carbon, and chromium, modern stainless steel may also contain other elements, such as nickel, niobium, molybdenum, and titanium. Nickel, molybdenum, niobium, and chromium enhance the corrosion resistance of stainless steel.

It is the addition of a minimum of 12% chromium to the steel that makes it resist rust, or stain ‘less’ than other types of steel. The chromium in the steel combines with oxygen in the atmosphere to form a thin, invisible layer of chrome-containing oxide, called the passive film. The sizes of chromium atoms and their oxides are similar, so they pack neatly together on the surface of the metal, forming a stable layer only a few atoms thick. If the metal is cut or scratched and the passive film is disrupted, more oxide will quickly form and recover the exposed surface, protecting it from oxidative corrosion. (Iron, on the other hand, rusts quickly because atomic iron is much smaller than its oxide, so the oxide forms a loose rather than tightly-packed layer and flakes away.) The passive film requires oxygen to self-repair, so stainless steels have poor corrosion resistance in low-oxygen and poor circulation environments. In seawater, chlorides from the salt will attack and destroy the passive film more quickly than it can be repaired in a low oxygen environment.

Types of Stainless Steel

The three main types of stainless steels are austenitic, ferritic, and martensitic. These three types of steels are identified by their microstructure or predominant crystal phase.

Austenitic:

Austenitic steels have austenite as their primary phase (face centered cubic crystal). These are alloys containing chromium and nickel (sometimes manganese and nitrogen), structured around the Type 302 composition of iron, 18% chromium, and 8% nickel. Austenitic steels are not hardenable by heat treatment. The most familiar stainless steel is probably Type 304, sometimes called T304 or simply 304. Type 304 surgical stainless steel is an austenitic steel containing 18-20% chromium and 8-10% nickel.

Ferritic:

Ferritic steels have ferrite (body centered cubic crystal) as their main phase. These steels contain iron and chromium, based on the Type 430 composition of 17% chromium. Ferritic steel is less ductile than austenitic steel and is not hardenable by heat treatment.

Martensitic:

The characteristic orthorhombic martensite microstructure was first observed by German microscopist Adolf Martens around 1890. Martensitic steels are low carbon steels built around the Type 410 composition of iron, 12% chromium, and 0.12% carbon. They may be tempered and hardened. Martensite gives steel great hardness, but it also reduces its toughness and makes it brittle, so few steels are fully hardened.

There are also other grades of stainless steels, such as precipitation-hardened, duplex, and cast stainless steels. Stainless steel can be produced in a variety of finishes and textures and can be tinted over a broad spectrum of colors.

This article comes from ABOUT edit released

 

What Is Stainless Steel and Why Is it Stainless?

In 1913, English metallurgist Harry Brearly, working on a project to improve rifle barrels, accidentally discovered that adding chromium to low carbon steel gives it stain resistance. In addition to iron, carbon, and chromium, modern stainless steel may also contain other elements, such as nickel, niobium, molybdenum, and titanium. Nickel, molybdenum, niobium, and chromium enhance the corrosion resistance of stainless steel.

It is the addition of a minimum of 12% chromium to the steel that makes it resist rust, or stain ‘less’ than other types of steel. The chromium in the steel combines with oxygen in the atmosphere to form a thin, invisible layer of chrome-containing oxide, called the passive film. The sizes of chromium atoms and their oxides are similar, so they pack neatly together on the surface of the metal, forming a stable layer only a few atoms thick. If the metal is cut or scratched and the passive film is disrupted, more oxide will quickly form and recover the exposed surface, protecting it from oxidative corrosion. (Iron, on the other hand, rusts quickly because atomic iron is much smaller than its oxide, so the oxide forms a loose rather than tightly-packed layer and flakes away.) The passive film requires oxygen to self-repair, so stainless steels have poor corrosion resistance in low-oxygen and poor circulation environments. In seawater, chlorides from the salt will attack and destroy the passive film more quickly than it can be repaired in a low oxygen environment.

Types of Stainless Steel

The three main types of stainless steels are austenitic, ferritic, and martensitic. These three types of steels are identified by their microstructure or predominant crystal phase.

Austenitic:

Austenitic steels have austenite as their primary phase (face centered cubic crystal). These are alloys containing chromium and nickel (sometimes manganese and nitrogen), structured around the Type 302 composition of iron, 18% chromium, and 8% nickel. Austenitic steels are not hardenable by heat treatment. The most familiar stainless steel is probably Type 304, sometimes called T304 or simply 304. Type 304 surgical stainless steel is an austenitic steel containing 18-20% chromium and 8-10% nickel.

Ferritic:

Ferritic steels have ferrite (body centered cubic crystal) as their main phase. These steels contain iron and chromium, based on the Type 430 composition of 17% chromium. Ferritic steel is less ductile than austenitic steel and is not hardenable by heat treatment.

Martensitic:

The characteristic orthorhombic martensite microstructure was first observed by German microscopist Adolf Martens around 1890. Martensitic steels are low carbon steels built around the Type 410 composition of iron, 12% chromium, and 0.12% carbon. They may be tempered and hardened. Martensite gives steel great hardness, but it also reduces its toughness and makes it brittle, so few steels are fully hardened.

There are also other grades of stainless steels, such as precipitation-hardened, duplex, and cast stainless steels. Stainless steel can be produced in a variety of finishes and textures and can be tinted over a broad spectrum of colors.

This article comes from ABOUT edit released

 

Alloy Steels broad overview

Types of Alloy Steels: Alloy steels are generally classified as low-alloy steels or high-alloy steels. Low-alloy steels have similar microstructures and heat treatment requirements to plain carbon steels and contain up to 3 or 4 % of alloying additions in order to increase strength, toughness or hardenability. High-alloy steels have structures and heat treatments that differ considerably from plain carbon steels. A surumary of a few selected alloy steels is given below.

Low alloy constructional steels: As well as carbon, these contain additions of Mn, Ni, Cr, Mo etc. Nickel strengthens ferrite in solution but also causes graphitisation of carbides. For this reason it is usually accompanied by strong carbide stabilisers such as chromium, which also strengthens ferrite and increases hardenability. The Ni is usually in the majority, with maximum amounts 4.25% Ni and 1.25%Cr, often resulting in air hardenable steels. Tempering in the range 250oC -4000C can result in ‘temper brittleness’, but this can be minimised by additions of 0.3% Mo giving ‘nickel-chrome-moly’ steels, used in axles, shafts, gears, con-rods etc. Some Mn can be substituted for more expensive Ni. (See Table for more details).

Alloy tool and die steels: (B5970 and B54659). These acquire hardness and wear resistance by incorporating carbides that are harder than cementite, while retaining strength and some toughness. They also have high hardenability and the ability to resist the tempering effects of use in hot working dies and from frictional heating in high speed machining operations. Alloying additions include Cr, W, Mo and V, which are strong carbide formers and also stabilise ferrite and martensite.

A typical composition is 18%W, 4%Cr, 1%V, 0.8%C. Quenching from high temperatures (13000C) is necessary, in order to dissolve as much W and C in austenite, for maximum hardness and heat resistance, followed by heating to 3000C – 4000C to transform any retained austenite to martensite then to 5500C to relieve internal stresses and produce carbide particles in a toughened martensite matrix. This martensite is then temper resistant up to 7000C.

This article comes from http://www.tech.plymouth.ac.uk/sme/desnotes/stainless.htm