How To Heat Treat Spring Steel?

Do you know How To Heat Treat Spring Steel? You must begin with the proper steel. Although many materials are available, many spring steel sheets are low alloy, medium-high carbon steels. You’re searching for a good combination of tensile strength and toughness.

The springs will be tempered after quench hardening (most are oil hardening). Springs are frequently tempered to the extremes of the alloy’s tempering range. This results in a vivid blue oxide color for low alloy steel.

The precise heat treatment technique will be determined by the alloy utilized and the thickness of the ruling section. Following annealing, the spring is usually hot or cold-formed, then heat-treated before going through any final grinding and finishing procedures after tempering.

Heat Treat Spring Steel

How To Heat Treat Spring Steel?

First, you’ll need steel that can be heat treated by heating it until it loses its ferromagnetic property and then quenching it in a liquid. Typically, this refers to steel with a 0.5 to 1.0 percent carbon content. Other elements, such as Manganese, are present in minor amounts in most steels used to make springs.

The heat treatment process can take many forms, particularly in specialized heat-treating shops. You mold the metal (in its regular or annealed) into the desired spring shape at its most basic level. Then you heat it until it loses its magnetic attraction.

Then you quickly cool it down with a suitable liquid, such as water, brine, 50/50 antifreeze, or oil. The metal has hardened to the point that it could be used as a file, but it is too brittle to be utilized as a spring. Second heat treatment is necessary, which usually involves heating it to around 560 degrees Fahrenheit (293 degrees Celsius).

The surfaces of a few locations on a hardened item can be polished to a dazzling white finish and utilized as tempering indicators. When the thing is reheated softly, carefully, and uniformly, it will turn yellow, then brown, and finally blue (as in clock-spring blue) when the surface temperature is reached.

Tempering is ideally done in a temperature-controlled oven, although several cruder procedures that need more operator skill and judgment have been used successfully for a long time.

What Is The Process Of Making Steel?

I believe I can answer this question as a steelmaker with over 40 years of experience. Steel production can be divided into two categories.

1st Method

In an electric arc furnace (EAF), place ferrous scrap (steel scrap, iron scrap), lower the three graphite electrodes, and switch on the electric current. The transformer capacity of a modern EAF will typically be in the range of 100MVA to 200MVA.

The scrap will begin to melt when an electric current is applied, and then oxygen and fuel (generally natural gas) will be blown in through sidewall burners, impinging on the scrap. Alloying elements such as Mn, Mo, Cr, Si, Ni, and others are added to the steel after melted, depending on the steel grade being made. The steel can be tapped from the furnace 40 minutes after starting.

Method 2 (Which Is More Complex But Results In Higher-Quality Steel)

To drive out the volatiles, a mixture of high-volatile, medium-volatile, and low-volatile coal (volatile referring to the relative amount of xylene, toluene, butadiene, and other aromatic hydrocarbons) is coked (heated without air) for 17 or 18 hours. The resulting substance is known as “coke,” It is made up of carbon and roughly 9% to 12% ash.

The coke, along with iron ore Fe2O3 and some limestone as flux (flux to make slag, which contains the impurities), is placed into a blast furnace, and hot air is forced in to burn the coke and also to reduce the Fe2O3 to Fe plus CO and CO2. The output is liquid iron, tapped from the blast furnace at around 1400 degrees Celsius. Because the saturation level for carbon in iron is 4.2 wt%, this iron contains 4.2 wt% carbon.

This molten iron is transported to a steelmaking furnace and deposited into a furnace that contains 15% to 25% ferrous scrap (meaning 15 percent to 25 percent of the total metallic charge is ferrous scrap). The carbon content of the liquid iron is then reduced from 4.2 percent to 0.10 percent to 0.40 percent by eliminating carbon as CO (90 percent) and CO2 (40 percent) (10 percent).

Steel is the name given to the end product. Manganese Mn and other elements such as Mo, Cr, Si, Ni, and others are added depending on the steel grade. For example, if stainless steel is to be produced, chromium must account for at least 10.5 percent of the total weight.

What Is The Best Way To Bend Hardened Steel?

You don’t have it. Steel must be pliable enough to withstand bending without fracturing before it can be bent. Hardened steel has lost its elasticity in exchange for becoming more complex and more robust. If you try, it’ll just shatter.

By heating it and allowing it to cool gently, you’ll be able to anneal it or, at the very least, draw back the temper. Then bow your knees. Finally, heat, quench, and maybe temper it to return it to the hardened state it was in when you started.

When Structural Steel Is Heated, Why Does It Weaken?

When a substance is sufficiently heated, it weakens. Consider butter: it may be quite hard right out of the refrigerator. When butter is brought to room temperature, it slices significantly easier. When butter is gently heated, it crumbles under its weight.

Titanium alloys, for example, have a high melting point (3,034F), but their strength plummets at just 800F. Stainless steels are frequently utilized in place of titanium for temperatures between 800 and 1500 degrees Fahrenheit because they retain higher power despite having a lower melting point. However, titanium alloys and stainless steels weaken over time as the temperature rises.

“Superalloys,” for example, are a group of metals (cobalt-based, nickel-based, and iron-based) with functional strength up to 2/3 of their melting temperatures. They still weaken at high temperatures, but they’ve been dubbed “super” since most other metals behave like warm butter long before they reach 2/3 of their melting points. The following are some of the reasons why materials weaken with temperature:

  1. With increasing temperature, atoms and dislocations in crystals** become more mobile, allowing the material to move more freely (i.e., it gets softer).
  2. Metals are crystallized substances. Most heat treatments and mechanical shaping procedures change the atoms’ crystalline arrangement.
  3. The material may switch from one crystal form to another (e.g., face-centered cubic to body-centered cubic). Higher temperature forms are less stable, making them more susceptible to the processes outlined in point 1.

Standard structural steels are low-cost metals with only a few alloying elements, such as carbon for reinforcement and Manganese to reduce sulfur impurities. They don’t have any (expensive) alloying components needed to operate properly at high temperatures, which is OK. After all, structural steels are designed to support the walls of buildings at room temperature, not in furnaces.

Is Ordinary Steel More Challenging To Work With Than Stainless Steel?

Iron is iron, plain and simple. Steel is bare iron with a carbon content of 2.2 percent or 2%. Cast iron is a type of iron that contains more than 2% carbon. Stainless steel is plain iron with more than 16% chromium content.

When iron with >0.45 percent carbon is rapidly cooled from roughly 880°C, a microstructure known as martensite forms, and the steel becomes extremely hard, around 65hrc. The scarcity of carbon in stainless steel (austenitic variant) precludes the martensite transformation. Hence the hardness (25–30 HRC) will not alter.

On the other hand, Chrome is a solid carbide-forming element; thus, adding a bit of extra carbon will aid in the formation of chrome carbide (which will have good abrasive wear resistance). With a bit of carbon, you can make the martensitic variety, which is heat treatable and, depending on the composition, has an excellent hardness. On the other hand, the addition of carbon reduces corrosion resistance marginally. It’s a reasonable trade-off. For various uses, you must carefully select the material.


This is How To Heat Treat Spring Steel? Extinguishing oil and hardening in a lead shower solidifies the high carbon steel (Table 12.8). The tempered wire is typically used for leaps up to 12.5 mm in width. After that, it’s snaked.

When stresses aren’t too significant, these are universally appropriate for a wide range of curl springs. The best flexible breaking point and exhaustion qualities are achieved by heat-treating spring steel. The condition of the surface should be sound and smooth. Erosion and decarburization are highly detrimental to steel spring exhaustion strength.

Frequently Asked Questions

Is it possible to heat treat springs?

The benefits of heat treating springs include increased fatigue life, hardness, and flexibility. Heat treating a spring alters the material’s specific features, such as hardness, strength, toughness, and elasticity, all critical considerations for a high-quality spring.

Is it possible to harden spring steel?

The high yield strength of spring steel is accomplished through one of two production processes: (1) heat treatment or (2) work hardening. Heat treatment is used to harden steel by heating it and then quenching it to cool it down to room temperature quickly.

What is the temperature at which spring steel is tempered?

Spring steel tempering (300-500°C): utilized for spring steels and similar purposes. The hardness criterion is usually approximately 45 HRC. I used quenched and tempered steels, hot working tool steels, and high-speed steels at high temperatures (500°C or more).

What happens when spring is heated?

When you extend the spring and heat it to a specific degree, you’re essentially melting it and injecting the heat into the system, allowing molecules to re-position (re-distant) themselves, release tensions, and settle on a new position of minimal potential energy.

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