CNC Machining Heat Treatment Steel Parts
Heat Treatment
1, Experimental Purpose
2, Understanding The Basic Heat Treatment Process Of Carbon Steel
3, Study On The Relationship Between Cooling Conditions And Steel Properties
4, Analysis Of The Influence Of Quenching And Tempering Temperature On The Properties Of Steel
Experimental Equipment And Speciments
1, Experimental Equipment: Sx-10m-2.5 Box Test Resistance Furnace
2, Specimens: One For 45 Steel, One For 30 Steel And One For t8 Steel.
3, 45 Steel After Quenching Three Specimens
Experimental Principle
Heat Treatment Is An Important Metalworking Process To Improve The Properties Of Steel. The Heat Treatment Process Of Steel Is Characterized By Heating The Steel To a Certain Temperature, Holding a Certain Time, And Then Cooling At a Certain Cooling Rate. Through This Process, The Properties Of Steel Are Changed.
Experimental Contents And Steps
Quenching Heat Treatment Of Steel
Quenching Heat Treatment Is To Heat Carbon Steel To Ac3 Or Above 30-50 Degree c, And Then Put It Into Different Cooling Media For Rapid Cooling (Cooling Rate Is Higher Than Critical Cooling Rate, To Obtain Martensite Structure (m). The Structure After Quenching Is Martensite And Retained Austenite.
1, Determination Of Quenching Temperature
According To The Different Materials, The Critical Temperature Ac3 Or Ac1 Is Found In Table 1, And Then The Heating Temperature Can Be Obtained By Adding 40 Degree c.
Hypoeutectoid Steel (45 Steel, 30 Steel):
Heating Temperature = Ac3 + 40 Degree c
Hypereutectoid Steel (t10 Steel):
Heating Temperature = Ac1 + 40 Degree c
So The Final Heating Temperature Of 30 Steel Is= c + 40 c
Heating Temperature Of 45 Steel= c+40 c
Heating Temperature Of 45 Steel= c+40 c
2, The Determination Of Holding Time
After The Parts Are Heated To The Required Heating Temperature With The Furnace, They Need To Be Kept Warm For a Period Of Time To Ensure That The Whole Part Reaches The Required Temperature Evenly And Fully. It Is Obvious That The Holding Time Is Related To The Size And Shape Of The Workpiece.
By Measuring The Size Of The Parts, And Then Looking Up Table 2, Calculate The Holding Time Of The Specimen.
The Size Of The Part Is a Cylindrical Part With a Diameter Of 20 Mm.
3, Selection Of Cooling Medium
Cooling Is The Key Process Of Quenching. It Directly Affects The Properties Of Quenched Steel. The Cooling Rate Of Quenching Is Higher Than The Critical Cooling Rate To Obtain Supercooled Martensite. At The Same Time, The Internal Stress Should Be Controlled During The Cooling Process To Prevent Deformation And Cracking.
In Order To Ensure Quenching Effect, Appropriate Cooling Medium And Method Should Be Selected. In This Experiment, We Choose Water At Room Temperature As Cooling Medium.
4, Place The Workpiece In The Furnace, Set The Heating Control Temperature Of The Furnace Temperature Controller, And Start Heating.
5, When The Electric Furnace Reaches The Set Temperature, The Timing Of Heat Preservation Begins.
6, The Workpiece Is Discharged From The Furnace And Quickly Cooled In Water.
Tempering Heat Treatment Of Steel
The Martensite Structure Of Steel After Quenching Is Hard And Brittle, And There Is a Large Internal Stress In The Workpiece. The Purpose Of Tempering Is To Eliminate Internal Stress, Properly Reduce Hardness And Improve Processing Performance. According To Different Process Requirements, Tempering Can Be Divided Into Three Kinds: High Temperature Tempering, Medium Temperature Tempering And Low Temperature Tempering. The Selection Of Temperature And The Change Of Structure And Properties Are Shown In Table 3.
The Cooling Mode Of Tempering Is Air Cooling, i. e. The Workpiece Is Slowly Cooled At Room Temperature After Discharge From The Furnace.
1, The Workpiece Is Put Into The Furnace, The Heating Control Temperature Of The Furnace Temperature Controller Is Set, And The Heating Is Started.
2, When The Electric Furnace Reaches The Set Temperature, The Time Of Heat Preservation Begins, And The Time Of Heat Preservation Is 30 Minutes.
3, The Workpiece Is Discharged From The Furnace And Cooled Slowly At Room Temperature.