Method for joining dissimilar metal parts for improved weldability, weld quality, mechanical performance

Patent metadata

Field	Value
Publication number	US-2016207140-A1
Application number	US-201615000364-A
Country	US
Kind code	A1
Filing date	Jan 19, 2016
Priority date	Jan 19, 2015
Publication date	Jul 21, 2016
Grant date	—

Abstract

A method that improves the weldability, weld quality and mechanical performance of components involving concentric parts or non-concentric parts with closed weld seams of dissimilar metals and uses a temperature differential concept on one of the parts or both of the parts to be joined is proposed. This method results in improved weldability, prevents weld cracking both during and after welding, and significantly improves structural performance in terms of static, fatigue, and dynamic strengths. For dissimilar metal joints that are prone to formation of intermetallics, the differential temperature technique can significantly reduce the detrimental effects of intermetallics on mechanical performance of joints, as a result of favorable stress state generated by the temperature differential.

First claim

What is claimed is:

1 . A method of joining dissimilar metal parts with a closed bond line or a closed weld seam, the method comprising:
providing a first member; providing a second member being positioned relative to the first member; preheating the first member to a first temperature that is less than a temperature that results in predetermined degradation of material properties in the first member; maintaining the second member at a second temperature to maintain a predetermined temperature differential (ΔT) between the second temperature and the first temperature; and welding the first member and the second member together while the temperature differential is maintained.

2 . The method according to claim 1 wherein the temperature differential (ΔT) is defined as:

m


S
Y

α



E

≤

Δ



T

≤

T
*

-

T

member



2

where,
S γ Material yield strength of the first member in unit of [Pascal] or [MPa];
E: Material Young's modulus of the first member in unit of [Pascal] or [MPa];
α: Material thermal expansion coefficient of the first member in unit of

[

1

°




C
.

]

;

T*: Part 1 material characteristic temperature above which material property degradation occurs for intended applications; and
m: Dimensionless scaling parameter that varies between 0.2 to 0.4.

3 . The method according to claim 1 wherein the first temperature is greater than an ambient temperature.

4 . The method according to claim 1 wherein the first temperature is equal to an ambient temperature.

5 . The method according to claim 1 wherein the first temperature is less than an ambient temperature.

6 . The method according to claim 1 wherein the first temperature is greater than said second temperature by said temperature differential.

7 . The method according to claim 1 wherein the temperature differential is maintained irrespective of variation of the first temperature or the second temperature.

8 . The method according to claim 1 wherein the second temperature of the second member is maintained at an ambient temperature.

9 . The method according to claim 1 wherein the second temperature is less than an ambient temperature.

10 . The method according to claim 1 wherein the second temperature is greater than an ambient temperature.

11 . The method according to claim 1 wherein the second member is positioned concentrically relative to the first member.

Assignees

• Univ Michigan

Inventors

• Dong Pingsha
• Song Shaopin
• Pei Xianjun

Classifications

• B23K2203/20

  Operations & Transport · mapped topic

• B23K20/2275 Primary

  the other layer being aluminium · CPC title

• B23K20/24

  Preliminary treatment · CPC title

• B23K20/227

  with ferrous layer · CPC title

• B23K2103/20

  Ferrous alloys and aluminium or alloys thereof · CPC title