Spring Heat Treating Services

Why Should You Heat Treat Springs

Heat treatment of springs offers enormous advantages such as improved fatigue life, toughness, and ductility. When heat treating a spring it changes the special properties of the material such as hardness, strength, toughness and elasticity which are some of the key concerns for high-quality spring.

Heat Treatment Process:

All material is not heat-treated in the same way. Therefore, we first understand the purpose of your application and the environment in which the spring will operate. Then we choose the appropriate process that can be applied to your spring. To attain the expected tensile strength, we follow different heat treatment processes.

Heat treatment for some material is given below:

Spring Heat Treating Services FAQs

Why are springs heat treated?

Heat treating a spring improves fatigue life, toughness and ductility, and it changes the properties that matter most in service: hardness, strength, toughness and elasticity. Coiling work hardens the wire and locks residual stress into the material, and until that stress is dealt with the spring will not hold its free length or its rate under load. For precipitation hardening alloys the thermal cycle is also where most of the strength develops, so an unaged spring sits well below the tensile values its material data lists. Heat treatment is where a coiled shape becomes a working spring.

What is the difference between stress relief, age hardening and solution treatment?

Stress relief is a low temperature cycle that removes the residual stress coiling puts into the wire without meaningfully changing the microstructure. Age hardening, also called precipitation hardening, is a longer hold at moderate temperature that precipitates strengthening phases out of solution and raises tensile strength substantially. Solution treatment is a high temperature hold that dissolves those phases back into the matrix, resetting the material to a soft, uniform condition before it is aged again. Inconel X-750 is annealed at 2000 to 2200F, far above any stress relief temperature, and comes out at 130 ksi maximum tensile.

Is stress relieving after coiling optional?

No. Winding a spring deforms the wire past yield on the inside of each coil, and the residual stress left behind will relax on its own the first time the part is loaded or heated in service. The result is set: a spring that comes back shorter than its free length and delivers less load than the drawing calls for. A post-coiling thermal cycle stabilizes the part so its rate and free length stay where they were measured at inspection. Skipping the step does not save money, it moves the problem downstream into your assembly.

What heat treatment conditions does Coiling Technologies publish for Inconel X-750?

Six, each with a published tensile range. Annealed, heat treated at 2000 to 2200F, gives 130 ksi maximum. No. 1 Tempered in the as supplied condition gives 130 to 165 ksi. No. 1 Tempered plus Aged, aged after spring coiling at 1350F (732C) for 16 hours, gives 165 to 220 ksi. Spring Temper as supplied gives 160 to 220 ksi. Spring Temper plus Aged, aged after coiling at 1200F (649C) for 4 hours, gives 180 to 250 ksi. Spring Tempered plus Solution plus Aged, solution heat treated after coiling at 2100F (1149C) for 2 hours then air cooled, gives 145 to 190 ksi.

What conditions are published for Monel K-500?

Three. Annealed at 1600F (870C) gives 80 to 110 ksi tensile. Spring Temper in the as supplied condition gives 145 to 190 ksi. Spring Temper plus Aged, aged after spring coiling at 1000F (540C) for 10 hours, gives 160 to 200 ksi. The aging cycle earns its added time on fatigue limited work, since it lifts the bottom of the range by 15 ksi and the top by 10 ksi over as supplied spring temper. K-500 also ages at a much lower temperature and shorter hold than Inconel X-750, which reflects a different precipitation chemistry.

Why is aging done after coiling rather than before?

Aged material is strong and comparatively unforgiving, which makes it harder to coil accurately and more likely to crack at tight bend radii or in end configurations. Coiling in the softer as supplied or tempered condition and aging the formed spring afterward gets the geometry right first and develops full strength second. Every aged condition in the published tables reads the same way, aged after spring coiling: X-750 at 1350F for 16 hours or 1200F for 4 hours, K-500 at 1000F for 10 hours. The aging cycle relieves coiling stress at the same time, so one operation covers both jobs.

What heat treatment condition should my drawing call out?

Name the condition and the tensile range you expect, not the alloy alone. Inconel X-750 runs from 130 ksi maximum in the annealed condition to 250 ksi at the top of Spring Temper plus Aged, a spread wide enough that the alloy name by itself tells a manufacturer almost nothing about the finished spring. Call out the starting material condition, the post-coiling thermal cycle, and any customer standard you are building to, such as an applicable AMS or ASTM specification. If your requirement is written as a load and a cycle count rather than a temper, the engineering team can work backward to the condition that meets it.

How does Coiling Technologies choose the heat treatment for a given spring?

Not all material is heat treated the same way, so the starting point is the purpose of the application and the environment the spring will operate in. The appropriate process is then selected and applied to reach the expected tensile strength, which is why the published tables carry several routes per alloy instead of one. Heat treating runs in house in Houston alongside coiling, peening, coating and inspection, all under a single ISO 9001:2015 quality management system, so the thermal cycle a spring receives is recorded in the same traceability chain as its material certification and dimensional inspection report.