Basic Techiques of Blacksmithing: A Manual for Trainers (Peace Corps, 1982, 102 p.): Day 2: Session: 8. Heat treating

Basic Techiques of Blacksmithing: A Manual for Trainers (Peace Corps, 1982, 102 p.)

Day 2

		Session: 5. Properties of metals
		Session: 6. Forging a blacksmith's cold chisel
		Session: 7. Forging: a blacksmith's hot punch
		Session: 8. Heat treating

Session: 8. Heat treating

Total Time: 2 hours

Objectives.

* To define and discuss the terms hardening, annealing, and tempering.
* To anneal steel.
* To temper steel.
* To evaluate the problem-solving techniques used by the work teams.

Resources:

* Attachment 8-A, "Water and Oil Quenching"
* Andrews, pages 49-53
* Weyger, pages 36-37
* Weyger, back cover

Materials: Chisels and punches made during Sessions 6 and 7; a piece of coil spring for demonstration of tempering.

Procedures:

Step 1. (5 minutes)
Explain the session objectives and briefly outline the procedures.

Step 2. (15 minutes)
Distribute Attachment 8-A, "Water and Oil Quenching" and ask participants to define and discuss the terms annealing, hardening and tempering.

Trainer Notes

* Stimulate discussion by having participants describe common techniques used by local blacksmiths to harden steel.

* In defining the terms be certain that the following key points are discussed:

- the method of water-quenching in hardening and tempering
- the method of oil-quenching in hardening and tempering
- the concept of correct hardening temperature
- degrees of hardness
- the importance of annealing before hardening to relieve built-up stresses

* If available, distribute among the participants examples of tools which have been tempered and annealed and have them explain why it is important to harden certain tools.

Step 3. (20 minutes)
Using a punch and chisel blanks made during the previous sessions, demonstrate the proper techniques involved in annealing and tempering.

Trainer Notes

* Before beginning the demonstration, briefly describe the procedures to be followed and remind participants to observe carefully. During the demonstration, mention and point out the following:

- that annealing is a slow process which can take 20-30 minutes in some cases
- that the tempering area should not be windy since this causes scaling
- that the fire should be clean and free of clinkers and other debris
- that oxidation can be minimized by maintaining a low, steady air blast
- that care must be taken not to burn cutting edges while heating the stock
- signs and causes of steel stress and over-heating

* Following the demonstration, take a few minutes to ask participants to review and clarify the important techniques which they observed.

Step 4. (45 minutes)
Have the participants go to their work stations and anneal and temper the punches and chisels which they made in Sessions 6 and 7.

Trainer Notes

Circulate among the teams and provide assistance and guidance whenever necessary. However, it can be assumed that, at this point, the participants have become more comfortable with the forge environment. It is important to begin to limit interventions by the trainer to situations involving potential safety hazards and/or situations in which participants are involved in fruitless pursuits which will prevent successful completion of the task. In this manner, by encouraging as much independent experimentation as possible, the participants are given the opportunity to creatively solve their own problems.

Step 5. (15 minutes)
Reconvene the group and ask participants to discuss and share among themselves any difficulties which they encountered and what they did to overcome them.

Trainer Notes

Explain that they will be annealing and tempering other tools during the week to strengthen their skills.

Step 6. (20 minutes)
Have the participants discuss the problem-solving techniques used in their work teams up to this point.

Trainer Notes

* Briefly explain that in order to transfer the skills which they acquire during this training, participants will, most likely, be communicating and working cooperatively with a local blacksmith.

* Stimulate discussion and dialogue among the participants by asking the following questions:

- What are some examples of situations in which it was difficult for your team to work effectively?
- What was done to help solve these problems and move on?
- What factors served to inhibit effective problem-solving?
- What can be done in the future to improve your team's ability to work more effectively and cooperatively?
- To what extent does the work team design of this training reflect the situation of working with a local blacksmith at your sites?

Attachment 8-A

WATER AND OIL QUENCHING

Water quenching

WATER QUENCHING (Heat Reserve Method) - After bringing 3" of the blade end of the piece up to heat:

- quench only the tip (1½") leaving the next 2" or so unquenched.

- move the piece up and down ½" in water rapidly to prevent forming a fracture zone where heat contacts water. Maintain this until the heat glow has diminished to a dull cherry.

- Remove the piece from quench and briskly polish the blade surface with an abrasive. Hold the piece with blade upward and observe the color patina as the heat from reserve moves toward the edge. When the desired color reaches the edge, then quench quickly with a swirling motion.

Oil quenching

OIL QUENCHING - After bringing 2" of the blade end up to heat:

- with a swirling motion, plunge completely in oil quench bucket, holding the lid nearby in case of an oil flash. If the oil flashes, pull tongs out of the way and snuff fire with tight-fitting lid.

- After the piece has been quenched in oil and is cool to the touch, polish and draw color patina over a propane flame or in a forge, using a metal plate with a hole cut in it (or fire bricks) to direct heat to the piece.