---
title: "Define tempering in brief"
subject: "Civil Engineering Materials"
chapter: 8
key: "semester_3/civil_engineering_materials:tempering-define"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/tempering-define
site: BCT Engineering
---

# Define tempering in brief

Civil Engineering Materials · Chapter 8: Metals and Alloys

- Asked in: 2079 Bhadra, 1 marks
- Video: [Lecture Series - Tempering - Heat Treatment](https://www.youtube.com/watch?v=t3JiLJVZ7tU) — KARTHICK B
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/tempering-define
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-8

## Question

Define tempering.

## Short answer

Tempering is reheating quenched steel to 150-650°C, holding and air/oil cooling. It reduces brittleness and internal stresses of martensite, increasing toughness and ductility while some hardness is lost.

## Answer

**Tempering** is the reheating of hardened (quenched) steel to a temperature below the lower critical point (150-650 C), holding it there, and then cooling in air or oil. It reduces the brittleness and internal stresses of martensite and increases toughness and ductility, with some loss of hardness.

```text
 Temp
  ^
  |        ______ temper temp (150-650 C)
  |       /      \
  |      /        \ cool in air
  |     /          \
  +--------------------------> Time
```
Lower tempering temperature (150-300 C) retains hardness (cutting tools); higher (400-650 C) gives more toughness (springs, shafts).

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Tempering is
   A. Heating above critical
   B. Quenching
   C. Annealing
   D. Reheating hardened steel below lower critical point
   Answer: D. Reheat. (Key point: Definition)

2. Tempering
   A. Reduces brittleness, increases toughness
   B. Increases hardness
   C. Melts
   D. Hardens
   Answer: A. Toughens. (Key point: Effect)

3. Cutting tools use
   A. 650 C
   B. Low temper 150-300 C to retain hardness
   C. Above critical
   D. None
   Answer: B. Low. (Key point: Temperature)