Galling
When two metal surfaces are rubbed together under heavy pressure, and without lubrication, it is expected that galling (or even seizing) may result.
The "button and block" galling test has been used to evaluate the adhesive wear resistance of various stainless steels under nonlubricated conditions (Schumacher 1977). Specimens were considered galled if deep scoring and heavy surface damage were evident during examination of the surfaces at 10X magnification. The lightest load that caused galling was used to calculate the "threshold galling stress". Threshold galling stresses for selected stainless steel combinations are included in Table 8 (Schumacher 1977).
The data in Table 8 establish that many contacting stainless steel combinations are highly susceptible to galling. Most important, the data show that NITRONIC 60 can be used in contact with many stainless steels without concern for galling. Galling problems associated with the use of Type 304 nuts and bolts could very well be eliminated by fabricating one of the components from NITRONIC 60.

Table 8 - Threshold Galling Stresses for Stainless Steels*

Block Material	Button Material and Threshold Galling Stress, ksi
	Type 410	Type 416	Type 303	Type 304	Type 316	17-4PH	NITRONIC 60
Type 410**	3	4	4	2	2	3	50+***
Type 416	4	13	9	24	42	2	50+
Type 303	4	9	2	2	3	3	50+
Type 304	2	24	2	2	2	2	50+
Type 316	2	42	3	2	2	2	38
17-4PH	3	2	2	2	2	2	50+
NITRONIC 60	50+	50+	50+	50+	38	50+	50+

*Results in ksi based on "Button and Block" galling tests.
**Hardened and stress relieved to Bhn 352.
***50+ indicates that no galling occurred at 50,000 psi.

이진희님의 글
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Galling의 정확한 의미를 알고 싶습니다.

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Galling Test에 관한 규정이 ASTM에 있더군요
아래의 내용은 시험에 관한 개략적인 내용을 퍼온글이오니 도움이되시길..
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Threshold Galling Stress Test.

In the threshold galling or "button and block" test (ASTM G 98), a small button and a large block sample are machined to provided two flat surfaces with a 10- to 45-µin. AA finish. The couple is then compressed together at constant load with a hydraulic or screw-feed press. The test arrangement is presented in Figure 1. One specimen is slowly rotated one revolution relative to the other specimen. Sliding surfaces are then examined for the appearance of torn metal, which indicates that galling has occurred. If the specimens have not galled, new samples are tested at higher loads until galling occurs. Couples with higher-threshold galling stresses have greater resistance to galling.