What is EN42 used for?

Mainly springs and spring-like parts: flat springs, clutch plates, spring washers and blades that must flex and return.

EN42 or EN47 for springs?

EN47 is a chromium-vanadium alloy spring steel with better fatigue life and hardenability for larger, heavily loaded springs. EN42 is a cheaper plain carbon steel for thinner springs and plates.

It is not recommended: the high carbon makes the weld area hard and brittle. Join it mechanically or design it as one part.

EN42 spring steel: properties, hardness and uses

EN42 is a high-carbon plain carbon steel used mainly for springs. Hardened and tempered, it becomes hard and springy, so it is used for flat springs, clutch plates, spring washers, scraper blades and wear strips.

Quick facts

Type: High-carbon (spring) steel
Carbon: About 0.70–0.85%
Spring hardness: About 42–50 HRC after hardening and tempering
Hardening: Oil quench from about 800–830 °C
Forms: Strip, sheet, bar
Close equivalents: C75 / C80 (CK75), AISI 1075–1080

Equivalent grades

Standard	Grade
BS 970 (old)	EN42
EN / DIN	C75S, C80 (CK75 family)
AISI / SAE	1075 – 1080

Equivalents are close, not identical. Name the grade and standard on the drawing.

Heat treatment

Harden from about 800–830 °C, quench in oil
Temper to spring hardness: about 350–450 °C for roughly 42–50 HRC
Flat parts are often hardened in fixtures or presses to stay flat
Form or bend before hardening; hardened EN42 cracks if bent sharply

Typical uses

Flat springs and leaf springs
Clutch and friction plates
Spring washers and circlips
Scraper and doctor blades
Wear strips and shims

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Questions

What is EN42 used for?: Mainly springs and spring-like parts: flat springs, clutch plates, spring washers and blades that must flex and return.
EN42 or EN47 for springs?: EN47 is a chromium-vanadium alloy spring steel with better fatigue life and hardenability for larger, heavily loaded springs. EN42 is a cheaper plain carbon steel for thinner springs and plates.
Can EN42 be welded?: It is not recommended: the high carbon makes the weld area hard and brittle. Join it mechanically or design it as one part.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 15 October 2026.