mig controlwasteTOMindexlogo 

 

This Page Presents Welding 4130 Chrome Moly (Chromoly) Math, and Other Information About Welding 4130:

Click for BASIC 4130 WELDING DETAILS

Click for TECHNICAL & METALLURGICAL DETAILS

Click for WELDING HEAT TREATED 4130 CHROME MOLY

Click for METALLURGICAL DEFINITIONS

Click for WELDING A BETTER STEEL;  HY 130

Click for DEFINING "EFFECTIVE HEAT INPUT"

 

Video-Welding 4130 CrMoly

Math Used to Generate 4130 Information.

The Information Below;
bulletProvides the math equations that estimate the theoretical cooling rates for TIG welds in thin wall 4130 tubes.
bulletThe cooling rate equations were obtained from the Welding Handbook, Volume 1, 9th Edition, page 100.
bulletBoth thick and thin plate equations were developed by Professor C.A.  Adams et al.
 
The data is presented in a way so one can see the numbers from each part of the equation. As the thickness was increased so was the heat input.  A TIG process efficiency of 0.5 (50%) was used which is somewhat  higher than the sited Welding Handbook reference but errors on the side of predicting a slower cooling rate. The thin plate equation is for two dimensional heat flow and may be OK for a butt weld but a Tee fillet weld will have faster cooling rate. Therefore despite trying to error on the side of predicting slower cooling rates, they are all around the 1/4 in Jominy bar location. The exact cooling rate will be somewhat dependent on the diameter of the tube as well. However I would expect that perhaps 1/2 way around the joint the cooling rate would be similar to that predicted. As the complete circular weld is made the last part will have a preheat from the weld start. However if a brittle structure is formed in any area and a crack forms, that is sufficient to be a problem.
Equation Elements and Values
bullet

Rc = Cooling rate at weld centerline; deg F/min

bullet

k = Thermal Conductivity of metal; BTU/min in deg F

bullet

p = Density of metal; lb/in3

bullet

C = Specific Heat of metal; BTU/ (lb deg F)

bullet

h = thickness of metal; in

bullet

Hnet = Net heat input; BTU/in [V*I / ipm*.057*process efficiency]

bullet

Tc = Temperature which cooling rate is calculated; deg F

bullet

To = Initial plate temperature; deg F

 

Welding Cooling Equations from page 100 Welding Handbook Volume 1, 9th Edition

Thick Plate Equation =Rc =-[2*3.1416*k(Tc-To)2] / Hnet
Thin Plate Equation = Rc = 2*3.1416*kpC (h/Hnet)2(Tc-To)3

Calculate estimated cooling rate @ 1100 deg F for thin wall 4130 tube welds:

 

Tube = .040 in wall; V (volts) = 10; I (amps) = 70; travel = 12 ipm

Using thin plate equation:

bullet-2*3.1416*0.024*0.29*0.11= -.00481
bulletHnet = 1.66
bullet(h/Hnet)2 = 0.000579
bullet(Tc-To)3 = 1.07*109
bullet Rc = -2981 deg F / min = - 50 deg F / sec
Tube = .0625 in wall; V (volts) = 10; I (amps) = 90; travel = 11 ipm

Using thin plate equation:

bullet-2*3.1416*0.024*0.29*0.11= -.00481
bulletHnet = 2.33
bullet(h/Hnet)2 = 0.000718
bullet(Tc-To)3 = 1.07*109
bullet Rc = -3700 deg F / min = - 62 deg F / sec
Tube = .093 in wall; V (volts) = 10; I (amps) = 110; travel = 9 ipm

Using thin plate equation:

bullet-2*3.1416*0.024*0.29*0.11= -.00481
bulletHnet = 3.48
bullet(h/Hnet)2 = 0.000713
bullet(Tc-To)3 = 1.07*109
bullet Rc = -3671 deg F / min = - 61 deg F / sec
REFERENCES USED;
bulletUS Steel Atlas of Isothermal Transformation Diagrams
bulletRepublic Alloy steels
bulletR. A. Grange and Kiefer; "Transformation of Austenite on Continuous Cooling and Relation to Transformation at Constant Temperature."
bulletWalter Crafts and John Lamont; "Hardenability and Steel Selection."
bulletAWS Welding Handbook; Volume 1, 9th Addition

The "Gas Blast" at MIG Weld Starts Causes Problems:

1) Shielding Gas Waste - typically 50% of gas used

2) Inferior Weld Quality - due to air pulled in gas stream

See Patented Gas Saver System (GSSTM) Solution That Costs Less Than a Refill.

GSS  Works for TIG Welders with Foot Pedal or Thumb Control

If a Search Engine Found This Page 1st- - - We'd Suggest a Visit to The Basic Welding 4130 Page; Then Return.  Click Here

This page presents the equations that support the data in the 4130 Technical Details page.

ONE PAGE SUMMARY

PURCHASE GSS PRODUCT

 

FREE Corvette Accessory Installation Info

 

Check Out Welding Math Site

This Page Presents Welding 4130 Math, for Other Information:

Click for BASIC 4130 WELDING DETAILS

Click for TECHNICAL & METALLURGICAL DETAILS

Click for  EQUATIONS defining weld cooling rate in tubing

Click for WELDING HEAT TREATED 4130 CHROME MOLY

Click for METALLURGICAL DEFINITIONS

Click for WELDING A BETTER STEEL;  HY 130

Stop Wasting Shielding Gas!!

See YouTube Videos

Including Our Patented MIG Shielding

"Gas Saver System" (GSS)

 

Why MIG Gas Waste

Detailed Review of GSS

Short Overview of GSS-90 Seconds

What User Say About GSS

Welding Race Cars

Rat Rods-Then and Now

Welding: Go Green

Engineering A Pro Street / Street Rod

bullet

ENGINE - CLICK

bullet

TUNING HOLLEY CARB - CLICK

bullet

ENGINE COOLING- CLICK

bullet

WIRING - CLICK

bullet

CHASSIS - CLICK

 

"WARNING: "Weld Safely"