Skip to main content

What is heat Treatment ?

HEAT TREATMENT

•          It is a continuous process of HEATING, HOLDING AT A PARTICULAR TEMPERATURE FOR SPECIFIC TIME AND COOLING AT A PREDETERMINED RATE of metals to change their physical and mechanical properties, without letting it change its shape. . The most common application is metallurgical. Heat treatment could be said to be a method for strengthening materials but could also be used to alter some mechanical properties such as improving formability, machining, etc. It is very important manufacturing processes that can not only help manufacturing process but can also improve product, its performance, and its characteristics in many ways.

•          Engineering properties are modified by heat treatment processes so that structural components are able withstand specified operating conditions and have desired useful life.

The properties of steel can be improved by changing its structure at atomic level. This can be achieved through

i)              By Alloying Elements
ii)             By Heat Treatment

 a same type of steel can exhibit different type of properties under different heat treatment conditions. Such type of flexibility helps us to decide various manufacturing processes and ultimate uses of steel.

DETAILS OF HEAT TREATMENT

1.       Heating -> Rate of Heating
2.       Soaking -> Temp. & time of Soaking
3.       Cooling -> Rate & Medium of cooling

-               The properties of steel can be influenced by different combinations of the above parameters
-               Different composition and initial phases of material can also be influenced the properties after Heat Treatment.

PURPOSE OF HEAT TREATMENT

(1)     Soften the metal prior to shaping or cutting / Machining. 
(2)     Relieve the effects of strain hardening that occurs during cold forming.
(3)     Achieve the final strength and hardness required in the finished product as one of the end manufacturing processes.

TYPE OF HEAT TREATMENT

·         Body heat treatment
·         Surface heat treatment

TYPE OF THERMAL TREATMENT

  1. Annealing.
  2. Normalizing
  3. Hardening & Tempering.
  4. Stress Relieving
  5. Surface Hardening.



Labels:

Popular posts from this blog

The Brinell Hardness Test

The Brinell Hardness Test The Brinell hardness test method consists of indenting the test material with a 10 mm diameter hardened steel or carbide ball subjected to a load of 3000 kg. For softer materials the load can be reduced to 1500 kg or 500 kg to avoid excessive indentation. The full load is normally applied for 10 to 15 seconds in the case of iron and steel and for at least 30 seconds in the case of other metals. The diameter of the indentation left in the test material is measured with a low powered microscope. The Brinell harness number is calculated by dividing the load applied by the surface area of the indentation. The diameter of the impression is the average of two readings at right angles and the use of a Brinell hardness number table can simplify the determination of the Brinell hardness. A well structured Brinell hardness number reveals the test conditions, and looks like this, "75 HB 10/500/30" which means that a Brinell Hardness of 75 was obtained us...
Read more

VISUAL INSPECTION OF WELDING

VISUAL  INSPECTION OF WELDING INTRODUCTION Inspection starts with examination of the material prior to fabrication, scabs, seams, scale or other harmful surface conditions may be detected in visual inspection. The inspector should check the following : Weld preparation, dimensions and finish.  Clearance dimensions of backing strips.  Alignment and fit up to the pieces being welded.  Verification of cleanliness.  Visual Inspection During Welding Visual inspection checks details of the work while welding is in progress. Among the details to be checked are : Welding process.  Cleaning.  Preheat and inter pass temperature.  Joint preparation.  Filler metal.  Flux or shielding gas.  Chipping, grinding, or gouging.  Post heating temperature and time.  Visual Inspection After Welding Visual inspection is useful for finished-product verification of such items as : Profile irregularities of the weldment....
Read more

'NICK' BREAK (BEND) TEST

'NICK' BREAK (BEND) TEST Object :  As for fillet weld fracture, used on butt welds. Method: The specimen is cut transversely to the weld, and a saw cut is applied along the center of the weld face. The best place for the cut is at a start I stop. The specimen is fractured by bending or by hammer blows. The nick bend test will find internal defects. Reporting Results: Thickness of material.  Width of specimen.  Location of fracture.  Appearance of joint after fracture.
Read more